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Helical optical projection tomography
Digital Repository Infrastructure Vision for European Research (DRIVER)
A new technique termed Helical Optical Projection Tomography (hOPT) has been developed with the aim to overcome some of the limitations of current 3D optical imaging techniques. hOPT is based on Optical Projection Tomography (OPT) with the major difference that there is a translation of the sample in the vertical direction during the image acquisition process, requiring a new approach to image reconstruction. Contrary to OPT, hOPT makes possible to obtain 3D-optical images of intact long samp...
Live optical projection tomography
Optical projection tomography (OPT) is a technology ideally suited for imaging embryonic organs. We emphasize here recent successes in translating this potential into the field of live imaging. Live OPT (also known as 4D OPT, or time-lapse OPT) is already in position to accumulate good quantitative data on the developmental dynamics of organogenesis, a prerequisite for building realistic computer models and tackling new biological problems. Yet, live OPT is being further developed by merging ...
Colas, Jean-franc?ois; Sharpe, James
Amplified Dispersive Optical Tomography
CERN Multimedia
Optical coherence tomography (OCT) has proven to be a powerful technique for studying tissue morphology in ophthalmology, cardiology, and endomicroscopy. Its performance is limited by the fundamental trade-off between the imaging sensitivity and acquisition speed -- a predicament common in virtually all imaging systems. In this paper, we circumvent this limit by using distributed Raman post-amplification of the reflection from the sample. We combine the amplification with simultaneously performed dispersive Fourier transformation, a process that maps the optical spectrum into an easily measured time-domain waveform. The Raman amplification enables measurement of weak signals which are otherwise buried in noise. It extends the depth range without sacrificing the acquisition speed or causing damage to the sample. As proof of concept, single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate of 36.6 MHz is demonstrated.
Goda, Keisuke; Jalali, Bahram
Second harmonic optical coherence tomography
CERN Document Server
Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular and tissue structures, this technique offers contrast and resolution enhancement to conventional optical coherence tomography.
Jiang, Y; Wang, Y; Chen, Z; Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping
Integrated-optics-based optical coherence tomography
Optical coherence tomography (OCT) is a high resolution, imaging technique that has developed over the last 20 years from a complicated laboratory setup into a ready-to-use commercially available device. Instead of using electronic time gating as being used by ultrasound (US) imaging, in OCT, the optical analogue of US imaging, determines the time of flight using low coherence interferometry. To date, OCT has many clinical applications and is widely used in urology, cardiovascular imaging, de...
Anterior Segment Tomography with the Cirrus Optical Coherence Tomography
Optical coherence tomography (OCT) is an optical acquisition method to examine biological tissues. In recent years, OCT has become an important imaging technology used in diagnosing and following macular pathologies. Further development enabled application of optical coherence tomography in evaluation of the integrity of the nerve fiber layer, optic nerve cupping, anterior chamber angle, or corneal topography. In this manuscript we overview the use of OCT in the clinical practice to enable co...
Rodrigues, Eduardo B.; Margara Johanson; Penha, Fernando M.
Fiber optic based optical tomography sensor for monitoring plasma uniformity
International Nuclear Information System (INIS)
A new type of fiber optic based optical tomography sensor has been developed for in situ monitoring of plasma uniformity. Optical tomography inverts optical emission measurements into the actual plasma distribution without assuming radial symmetry. The new sensor is designed to operate with only two small windows and acquire the necessary data in less than a second. Optical tomography is being tested on an ICP-GEC RF plasma source. Variations in plasma uniformity are measured as a function of different plasma conditions
Optical coherence tomography in dermatology
Science.gov (United States)
Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 ?m, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.
Sattler, Elke; K�stle, Raphaela; Welzel, Julia
Optical Coherence Tomography: Technical Aspects
Optical coherence tomography (OCT) is a high-resolution, noninvasive, 3D imaging technique with great potential in both clinical and fundamental research applications in many areas. Owing to its exceptionally high spatial resolution and velocity sensitivity, the functional extension of OCT techniques can simultaneously provide tissue structure, blood perfusion, birefringence, and other physiological information and it has great potential for basic biomedical research and clinical medicine. OCT has the far-reaching potential to be a quantitative imaging technique that could impact many, as yet unexplored, areas and should therefore be considered a vital measurement tool. In this chapter, we will first discuss the principle of operation and then the practical aspects of the OCT system; we will also provide detailed discussion on different OCT schemes and its functional extensions.
Subhash, Hrebesh M.; Wang, Ruikang K.
Phase-Conjugate Optical Coherence Tomography
We demonstrate a new type of optical coherence tomography using only classical resources to achieve results that are typically associated with quantum-enhanced metrology: factor-of-two axial resolution enhancement and even-order dispersion cancellation.
Shapiro, Jeffrey H.; Le Gouet, Julien; Venkatraman, Dheera; Wong, Franco N. C.
Conical wavefronts in optics and tomography
A wide range of techniques in which the information is transferred by conical (nonspherical and nonplanar) wave fronts is considered. This is the first summary of papers published in the field of mesooptics and optical tomography. After the introduction into the new branch of modern optics - mesooptics -the properties of conical wavefronts are treated in detail. Some possible applications of mesooptics in science and technology are considered. The long history of mesooptics treated in the last chapter of this review lecture goes from the early stage of our Universe, gravitational lens, first publications in the last century and up-to-date innovations in optics, mesooptics and optical tomography. 3 refs
Optical Coherence Tomography in Glaucoma
Retinal nerve fiber layer (RNFL) thinning and optic nerve head cupping are key diagnostic features of glaucomatous optic neuropathy. The higher resolution of the recently introduced SD-OCT offers enhanced visualization and improved segmentation of the retinal layers, providing a higher accuracy in identification of subtle changes of the optic disc and RNFL thinning associated with glaucoma.
Berisha, Fatmire; Hoffmann, Esther M.; Pfeiffer, Norbert
Optical coherence tomography in conjunction with bronchoscopy
Energy Technology Data Exchange (ETDEWEB)
To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways. Methods: This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion. Results: The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall. Conclusions: It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology. (author)
Rodrigues, Ascedio Jose; Takimura, Celso Kiyochi; Lemos Neto, Pedro Alves; Figueiredo, Viviane Rossi, E-mail: email@example.com [Servico de Endoscopia Respiratoria, Hospital das Clinicas, Universidade de Sao Paulo (FM/USP), SP (Brazil)
Optical Phase-Space-Time-Frequency Tomography
We present a theoretical approach of constructing optical phase-space-time-frequency tomography (OPSTFT). This tomography can be measured by using a novel four-window optical imaging system based on two local oscillator fields balanced heterodyne detection. The OPSTFT is a Wigner distribution function of two independent Fourier Transform pairs, i.e., phase-space and time-frequency. From its theoretical and experimental aspects, it can provide information of position, momentum, time and frequency of a spatial light field with precision beyond the uncertainty principle limit. We believe that the four-window system can provide spatial and temporal properties of a wave field for quantum image processing and biophotonics.
Rojas, Paul; Sua, Yong Meng; Lee, Kim Fook
Optical tomography of the neonatal brain
A new method of assessing neurological function and pathology in the newborn infant is being developed based on the transmission of near-infrared light across the brain. Absorption by blood over a range of wavelengths reveals a strong dependency on oxygenation status, and measurements of transmitted light enable the spatial variation in the concentrations of the oxygenated and de-oxygenated forms of hemoglobin to be derived. Optical tomography has so far provided static three-dimensional maps of blood volume and oxygenation as well as dynamic images revealing the brain's response to sensory stimulation and global hemodynamic changes. The imaging modality is being developed as a safe and non-invasive tool that can be utilized at the cotside in intensive care. Optical tomography of the healthy infant brain is also providing a means of studying neurophysiological processes during early development and the potential consequences of prematurity. (orig.)
Hebden, Jeremy C. [University College London, Department of Medical Physics and Bioengineering, London (United Kingdom); Austin, Topun [University College London, Department of Paediatrics and Child Health, London (United Kingdom)
In vivo fluorescence lifetime optical projection tomography
We demonstrate the application of fluorescence lifetime optical projection tomography (FLIM-OPT) to in vivo imaging of lysC:GFP transgenic zebrafish embryos (Danio rerio). This method has been applied to unambiguously distinguish between the fluorescent protein (GFP) signal in myeloid cells from background autofluorescence based on the fluorescence lifetime. The combination of FLIM, an inherently ratiometric method, in conjunction with OPT results in a quantitative 3-D tomographic technique t...
Mcginty, James; Taylor, Harriet B.; Chen, Lingling; Bugeon, Laurence; Lamb, Jonathan R.; Dallman, Margaret J.; French, Paul M. W.
Varnish Ablation Control by Optical Coherence Tomography
Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are present...
Turbidity Measurement Using An Optical Tomography System
Turbidity is used to describe water quality and it can be caused by the presence of suspended particles and organic matter such as algae, clay and silt. The measurement of turbidity level of water is vital to domestic water supplies since it is related to public health and water treatment process. This paper presents an investigation on an optical tomography system to estimate the turbidity level in a sample of water. The optical sensors consist of infrared light-emitting diodes (LED) as t...
Sallehuddin Bin Ibrahim
Endoscopic Optical Coherence Tomography for Clinical Gastroenterology
Directory of Open Access Journals (Sweden)
Full Text Available Optical coherence tomography (OCT is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.
Tsung-Han Tsai
Optical coherence tomography used for jade industry
As an expensive natural stone, jade has a worldwide market. In the jade industry, the inspection and analysis basically rely on the human eye and/or experience, which cause unavoidable waste and damage of these expensive materials. Optical Coherence Tomography (OCT) is a fundamentally new type of optical sensing technology, which can perform high resolution, cross-sectional sensing of the internal structure of materials. As jade is almost translucent to infra red light, OCT becomes an ideal tool to change the traditional procedure to volume data based machine vision system. OCT can also be used for anti-counterfeit of the expensive jade ware.
Chang, Shoude; Mao, Youxin; Chang, Guangming; Flueraru, Costel
Application of longitudinal optical tomography for dental introscopy in vitro
The possibility of application of optical longitudinal tomography for revealing anatomic features of tooth structure in norm as biological objects with clearly defined anisotropy of dimensions and optical properties is studied. The application of longitudinal optical tomography for dental introscopy is substantiated, a schematic of the experimental setup is described, and the results obtained are discussed
Blood oxygenation monitoring by diffuse optical tomography
Diffuse optical tomography (DOT) makes it possible to reconstruct, in two or three dimensions, the internal structure of the biological tissues based on the distribution of the absorption coefficient and the reduced scattering coefficient, using optical measurements at multiple source - detector positions on the tissue surface. The measurement of the light intensity transmitted through the tissue can be also used to compute the haemoglobin and oxyhaemoglobin concentrations, measuring the selective absorption of the main blood chromophores by near infrared spectroscopy (NIRS). The spectral selectivity of the system and the evaluation of the blood volume and blood oxygenation (BV and OXY distributions), together with the reconstruction of the inner structure of the tissue, can improve the accuracy of early cancer diagnosis, based on the tissue angiogenesis characterisation. (application of lasers and laser-optical methods in life sciences)
VW Hyi: optical spectroscopy and Doppler tomography
We present high quality optical spectroscopy of the SU UMa-subtype dwarf nova, VW Hyi taken while the system was in quiescence. An S-wave is executed by the emission cores of the Hydrogen Balmer lines and by the emission lines of He I, Ca II, Fe II and He II. Using Doppler tomography we show it originates in the accretion stream-disc impact region. The He II emission is strongly phase-dependent, suggesting it originates exclusively within a hot cavity at the initial impact. ...
Smith, Amanda J.; Haswell, Carole A.; Hynes, Robert I.
Optical homodyne tomography with polynomial series expansion
We present and demonstrate a method for optical homodyne tomography based on the inverse Radon trans- form. Different from the usual filtered back-projection algorithm, this method uses appropriate polynomial series to expand the Wigner function, the marginal distribution and discretize Fourier space. We show that this technique solves most technical difficulties encountered with kernel deconvolution based methods and recon- structs overall better and smoother Wigner functions. We also gives estimators of the reconstruction errors for both methods and shows improvement in noise handling properties and resilience to statistical errors.
Benichi, Hugo
Fiber optic based optical coherence tomography (OCT) for dental applications
We have developed a hand-held fiber optic based optical coherence tomography (OCT) system for scanning of the oral cavity We have produced, using this scanning device, in viva cross-sectional images of hard and soft dental tissues in human volunteers Clinically relevant anatomical structures, including the gingival margin, periodontal sulcus, and dento-enamel junction, were visible in all the images The dento-enamel junction and the alveolar bone were identifiable in approximately two thirds of the images These images represent, to our knowledge, the first in viva OCT images of human dental tissue.
Everett, M. J., LLNL
In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics
Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.
Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S
Blood optical clearing studied by optical coherence tomography
The main limitation of optical imaging techniques for studying biological tissues is light scattering leading to decreasing of transmittance, which lowers the imaging quality. In this case, an immersion method for optical clearing of biological tissues can provide a possible solution to this problem, because the application of biocompatible clearing agents can reduce light scattering. Optical clearing represents a promising approach to increasing the imaging depth for various techniques, for example, various spectroscopy and fluorescent methods, and optical coherence tomography (OCT). We investigate the improvement of light penetration depth in blood after application of polyethylene glycol, polypropylene glycol, propylene glycol, and hemoglobin solutions using an OCT system. Influence of clearing agents on light transport in tissues and blood was also investigated in the mouse tail vein.
Zhernovaya, Olga; Tuchin, Valery V.; Leahy, Martin J.
Resolution improvement in emission optical projection tomography
A new imaging technique called emission optical projection tomography (eOPT), essentially an optical version of single-photon emission computed tomography (SPECT), provides molecular specificity, resolution on the order of microns to tens of microns, and large specimen coverage (? 1 cubic centimetre). It is ideally suited to gene expression studies in embryos. Reconstructed eOPT images suffer from blurring that worsens as the distance from the axis of rotation increases. This blur is caused in part by the defocusing of the lens' point-spread function, which increases with object distance from the focal plane. In this paper, we describe a frequency space filter based on the frequency-distance relationship of sinograms to deconvolve the distance-dependent point-spread function and exclude highly defocused data from the eOPT sinograms prior to reconstruction. The method is shown to reduce the volume at half-maximum of the reconstructed point-spread function to approximately 20% the original, and the volume at 10% maximum to approximately 6% the original. As an illustration, the visibility of fine details in the vasculature of a 9.5 day old mouse embryo is dramatically improved
Optical tomography of the aurora and EISCAT
Full Text Available Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site.Key words. Tomography � Aurora � EISCAT � Ionosphere � Conductivity
H. U. Frey
Three-Dimensional Optical Coherence Tomography
Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.
Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga
Nonlinear inversion schemes for fluorescence optical tomography.
Fluorescence optical tomography is a non-invasive imaging modality that employs the absorption and re-emission of light by fluorescent dyes. The aim is to reconstruct the fluorophore distribution in a body from measurements of light intensities at the boundary. Due to the diffusive nature of light propagation in tissue, fluorescence tomography is a nonlinear and severely ill-posed problem, and some sort of regularization is required for a stable solution. In this paper we investigate reconstruction methods based on Tikhonov regularization with nonlinear penalty terms, namely total-variation regularization and a levelset-type method using a nonlinear parameterization of the unknown function. Moreover, we use the full threedimensional nonlinear forward model, which arises from the governing system of partial differential equations. We discuss the numerical realization of the regularization schemes by Newtontype iterations, present some details of the discretization by finite element methods, and outline the efficient implementation of sensitivity systems via adjoint methods. As we will demonstrate in numerical tests, the proposed nonlinear methods provide better reconstructions than standard methods based on linearized forward models and linear penalty terms. We will additionally illustrate, that the careful discretization of the methods derived on the continuous level allows to obtain reliable, mesh independent reconstruction algorithms. PMID:20562032
Freiberger, Manuel; Egger, Herbert; Scharfetter, Hermann
Optical coherence tomography for diagnosing periodontal disease
We have, in this preliminary study, investigated the use of optical coherence tomography for diagnosis of periodontal disease. We took in vitro OCT images of the dental and periodontal tissues from a young pig and compared them to histological sections. These images distinguish tooth and soft tissue relationships that are important in diagnosing and assessing periodontal disease. We have imaged the attachment of gingiva to the tooth surface and located the cemento-enamel junction. This junction is an important reference point for defining attachment level in the diagnosis of periodontal disease. the boundary between enamel and dentin is also visible for most of the length of the anatomical crown, allowing quantitation of enamel thickness and character.
Colston, Bill W.; Everett, Matthew J.; da Silva, Luiz B.; Otis, Linda L.; Nathel, Howard
Source intensity profile in noncontact optical tomography.
Noncontact optical tomography in reflection mode is often the only possible configuration when imaging the expression of green fluorescent protein (GFP) or other fluorescent proteins in live animals owing to the short penetration depth of visible light. When imaging in reflection mode using noncontact approaches (i.e., without the use of fibers coupled to tissue), correctly accounting for the intensity profile of the source at the surface is a difficult task, usually needing to fit for source positions and/or approximating these to point sources. In this Letter we present a rigorous theoretical approach that directly accounts for the source's intensity profile and verify it using in vivo data from GFP-expressing mice. We show how this approach improves image quality and resolution, while considerably simplifying the forward and inverse problems of the image reconstruction process. PMID:20664664
Sarasa-Renedo, Ana; Favicchio, Rosy; Birk, Udo; Zacharakis, Giannis; Mamalaki, Clio; Ripoll, Jorge
Fused Entropy Algorithm in Optical Computed Tomography
Full Text Available In most applications of optical computed tomography (OpCT, limited-view problems are often encountered, which can be solved to a certain extent with typical OpCT reconstructive algorithms. The concept of entropy first emerged in information theory has been introduced into OpCT algorithms, such as maximum entropy (ME algorithms and cross entropy (CE algorithms, which have demonstrated their superiority over traditional OpCT algorithms, yet have their own limitations. A fused entropy (FE algorithm, which follows an optimized criterion combining self-adaptively ME with CE, is proposed and investigated by comparisons with ME, CE and some traditional OpCT algorithms. Reconstructed results of several physical models show this FE algorithm has a good convergence and can achieve better precision than other algorithms, which verifies the feasibility of FE as an approach of optimizing computation, not only for OpCT, but also for other image processing applications.
Xiong Wan
Parameter and structure reconstruction in optical tomography
Many reconstruction problems in optical tomography, such as the imaging of haematoma in the brain, or breast tumour screening, require the detection and localisation of well-defined objects on a homogeneous or weakly varying background. A conventional parameter identification approach is to represent the image in a finite dimensional set of basis functions and to find the coefficients of this set using an optimisation strategy. Shape-based reconstruction techniques on the other hand, seek to find the boundaries of objects and possibly a representation of the interior either as constant or slowly varying functions. In this paper we compare both explicit and implicit shape reconstruction methods for the simultaneous recovery of absorption and diffusion inclusions in a three-dimensional scattering medium. Images reconstructed from simulated frequency-domain boundary measurements are compared to a voxel-based conjugate gradient method. The results demonstrate the feasibility of the shape based methods.
Optical coherence tomography imaging of macular oedema.
Macular oedema (ME) occurs in a wide variety of pathological conditions and accounts for different degrees of vision loss. Early detection of ME is therefore critical for diagnosis and therapeutic management. Optical coherence tomography (OCT) is a non-contact, diagnostic method that uses infrared light, which allows the analysis of the retinal structure by means of high-resolution tomographic cross sections. The identification, localisation, quantification and long-term follow-up of fluid collections are the most important capabilities of OCT. Since the introduction of OCT in clinical practice, it has become an invaluable diagnostic tool and different patterns of ME have been reported. The purpose of this manuscript is to review OCT profiles of ME according to the aetiology and describe what has been reported regarding intraretinal features in vivo. PMID:24934220
Trichonas, George; Kaiser, Peter K
Optical coherence tomography analysis of axonal loss in band atrophy of the optic nerve
Aims: To measure axonal loss in patients with band atrophy of the optic nerve caused by optic chiasm compression using optical coherence tomography and to evaluate its ability in identifying this pattern of retinal nerve fibre layer (RNFL) loss.
Monteiro, M. L. R.; Leal, B. C.; Rosa, A. A. M.; Bronstein, M. D.
Optical coherence tomography used for internal biometrics
Traditional biometric technologies used for security and person identification essentially deal with fingerprints, hand geometry and face images. However, because all these technologies use external features of human body, they can be easily fooled and tampered with by distorting, modifying or counterfeiting these features. Nowadays, internal biometrics which detects the internal ID features of an object is becoming increasingly important. Being capable of exploring under-skin structure, optical coherence tomography (OCT) system can be used as a powerful tool for internal biometrics. We have applied fiber-optic and full-field OCT systems to detect the multiple-layer 2D images and 3D profile of the fingerprints, which eventually result in a higher discrimination than the traditional 2D recognition methods. More importantly, the OCT based fingerprint recognition has the ability to easily distinguish artificial fingerprint dummies by analyzing the extracted layered surfaces. Experiments show that our OCT systems successfully detected the dummy, which was made of plasticene and was used to bypass the commercially available fingerprint scanning system with a false accept rate (FAR) of 100%.
Chang, Shoude; Sherif, Sherif; Mao, Youxin; Flueraru, Costel
Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction
A decade of research has pushed photoacoustic computed tomography to the forefront of molecular-level imaging, notes SPIE Fellow Lihong Wang (Washington University, St. Louis) in his plenary talk, "Photoacoustic Tomography: Ultrasonically Beating Optical Diffusion and Diffraction." Modern optical microscopy has resolution and diffraction limitations. But noninvasive functional photoacoustic computed tomography has overcome this limit, offering deep penetration with optical contrast and ultrasonic resolution of 1 cm depth or more -- up to 7 cm of penetration in some cases, such as evaluating sentinel lymph nodes for breast cancer staging. This opens up applications in whole body imaging, brain function, oxygen saturation, label-free cell analysis, and noninvasive cancer biopsies.
Wang, Lihong
Full 3D displacement field measurement by Optical Scanning Tomography and PIV Tomography
Full Text Available This work is about the development of new techniques for the measurement of the three components of the velocity inside a volume. A comparison of two techniques, optical scanning tomography and algebraic reconstruction tomography method, is performed with 3D displacement tests of transparent solid blocks.
Tremblais B.
Computed tomography of sarcoidosis of the optic nerve
Two patients with optic nerve sarcoidosis, one proven by an open biopsy of the optic nerve, the other by clinical evidence of sarcoidosis and a positive conjunctival biopsy, were examined by computed tomography. In both cases increased diameter and pathological enhancement of the involved optic nerves were demonstrated.
Dubois, P.J.; Beardsley, T.; Klintworth, G.; Sydnor, C.; Cook, W.; Osborne, D.; Heinz, E.R.; Drayer, B.P.
Two patients with optic nerve sarcoidosis, one proven by an open biopsy of the optic nerve, the other by clinical evidence of sarcoidosis and a positive conjunctival biopsy, were examined by computed tomography. In both cases increased diameter and pathological enhancement of the involved optic nerves were demonstrated. (orig.)
Optical coherence tomography in a patient with congenital vitreous cyst.
A case of congenital vitreous cyst is presented. An optical coherence tomography scan has been performed, which has shown that the cyst is free floating and is multilobular. Its content was hyper-reflective. PMID:24962488
Dragnev, Daniel; Shanmugalingam, Sinnathamboo
Attenuation compensation for optical coherence tomography imaging
Optical coherence tomography (OCT) is a noninvasive technique that provides micrometer-scale imaging of tissue. As most biological tissues are considered turbid, it causes attenuation of the OCT signal and limits the depth penetration. Although a few algorithms had been developed to compensate the attenuation, almost all of them need to extract the scattering parameters before doing the compensation procedure. Because the real biological samples are anisotropic and multilayer-like structure, it is not time-efficient to model and solve these scattering parameters. This paper introduces a new method to compensate the OCT signal attenuation in depth. By analyzing the input signal, a compensation function is adaptively derived for each A-scan line, which can be used effectively to compensate the energy loss in the large sections and enhance the details in the deep, dark-like areas. Three bio-samples, a piece of onion, a Poecilia Wingei fish and a piece of rabbit abdominal aorta, were used to test our method. OCT images obtained by a swept-source OCT system were processed by the proposed method. Results show the visualization of structures in OCT images has been evidently improved, especially in deep region.
Chang, Shoude; Flueraru, Costel; Mao, Youxin; Sherif, Sherif
We present high quality optical spectroscopy of the SU UMa-subtype dwarf nova, VW Hyi taken while the system was in quiescence. An S-wave is executed by the emission cores of the Hydrogen Balmer lines and by the emission lines of He I, Ca II, Fe II and He II. Using Doppler tomography we show it originates in the accretion stream-disc impact region. The He II emission is strongly phase-dependent, suggesting it originates exclusively within a hot cavity at the initial impact. We map the ionization structure of the stream-disc interaction region. One possible interpretation of this is that the Balmer hotspot lies downstream of the He II hotspot in the outer accretion disc, with the He I and Ca II hotspots at intermediate locations between the two. This suggests that Balmer emission is suppressed until material has cooled somewhat downstream of the impact site and is able to recombine. We favour a phase offset of 0.15+/-0.04 between the photometric ephemeris and inferior conjunction of the mass donor. The white d...
Smith, A J; Hynes, R I; Smith, Amanda J.; Haswell, Carole A.; Hynes, Robert I.
Polarization sensitive optical coherence tomography in dentistry
Optical coherence tomography (OCT) is a noninvasive and noncontact technique for obtaining cross-sectional images of biologic structure, which was initially introduced to depict the transparent tissue of the eye. It employs the partial coherence properties of a light source to image structures with high resolution (< 20 (m). Recently, this technique has also been applied in turbid media. This tomographic imaging is analogous to conventional ultrasound B mode imaging, except that OCT measures the intensity of backreflected infrared light rather than acoustical waves. First applications, of OCT in dentistry for diagnosing periodontal disease have been reported by Colston et al. presenting in vitro OCT images of the dental and periodontal tissues of porcine premolar teeth. In this work, the feasibility of polarisation sensitive OCT for dental material is suggested. In contrast with conventional OCT, where the magnitude of backscattered light as a function of depth is imaged, backscattered light is used to image the magnitude of the birefringence in the sample as a function of depth. Partial loss of birefringence is known to be an early indication of incipient caries or tissue thermal damage. Applying this technique for caries diagnosis or guidance regarding optimal dosimetry for thermally mediated laser therapeutic procedures, polarisation sensitive OCT would represent a promising new technology for dentistry. (author)
Optical Coherence Tomography Findings in Autoimmune Retinopathy
PURPOSE To report optical coherence tomography (OCT) features of patients with autoimmune retinopathy. DESIGN Consecutive case series. METHOD Eight patients who presented with unexplained loss of central vision, visual field defects, and/or photopsia were diagnosed with autoimmune retinopathy based on clinical features, electroretinogram (ERG) findings, and serum antiretinal antibody analysis. All patients underwent OCT testing of the macula and nerve fiber layer (NFL). RESULTS Outer retinal abnormalities and/or decreased macular thickness on OCT were seen in all patients. Macular OCT showed reduced central macular and foveal thicknesses in 6 patients (mean thickness 143 � 30 ?m and 131 � 29 ?m respectively). In all but 1 patient, loss of the photoreceptor layer or disruption of the photoreceptor outer and inner segment junction was noted. Three patients showed only mild to moderate focal NFL loss. CONCLUSIONS Retinal atrophy and reduced macular thickness on OCT are predominant features in patients with autoimmune retinopathy. OCT provides objective measures of retinal damage and may offer clues toward understanding the mechanism of visual dysfunction and the diagnosis of autoimmune retinopathy.
Nano-sensitive optical coherence tomography
Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated.Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated. Electronic supplementary information (ESI) available: Theory of the nsOCT. Figure: axial spatial period profiles for two selected points within the sample for second and fiftieth frames and averaged over all frames before (0 nm) and after (30 nm) nanoscale structural changes. Videos 1 and 2: axial spatial period profiles for selected points within tubes with intralipid versus time where fast structural changes can be seen. Videos 3 and 4: axial spatial period profiles for selected points outside from tubes with intralipid versus time where slow structural changes can be seen. Video 5: nsOCT imaging of the structural changes within tubes with intralipid. Videos 6 and 8: axial spatial period profiles for selected points within human fingertip versus time where slow structural changes can be seen. Videos 7 and 9: axial spatial period profiles for selected points within human fingertip versus time where fast structural changes can be seen. Video 10: nsOCT imaging of the structural changes within human fingertip in vivo. See DOI: 10.1039/c3nr06132a
Alexandrov, Sergey A.; Subhash, Hrebesh M.; Zam, Azhar; Leahy, Martin
Optical coherence tomography of central serous chorioretinopathy
Full Text Available AIM:To observe the imaging features of the foveal photoreceptor layer in eyes with central serous chorioretinopathy(CSCusing frequency-domain optical coherence tomography(FD-OCTand to find the relationship between best-corrected visual acuity(BCVAand the morphology of thickness of the outer nuclear layer.METHODS: Totally 58 eyes from 54 CSC patients and 60 eyes from 30 healthy volunteers as the control group were selected. FD-OCT scan was performed on all the patients and volunteers. FD-OCT scan of 6mm horizontal line was performed, the scan depth was 1.9mm with a 5.8mm�5.8mm transverse area, the vertical and horizontal resolution was 5?m and 18?m respectively. The scan mode was 512�496. The morphological changes of FD-OCT on different stages of CSC were observed and the relationship between best-corrected visual acuity(BCVAand the morphology of thickness of the outer nuclear layer were analyzed.RESULTS: Simple serous neuroepithelial layer detachment and simple serous neuroepithelial layer detachment associated with pigment epithelial layer detachment at macula were about 84.5% of all the patients. Thickness of the outer nuclear layer was thinner from acute stage to chronic stage of CSC, and the relationship between thickness of the outer nuclear layer and BCVA was negative.CONCLUSION: FD-OCT can detect the detailed morphologic changes and pathological morphology at the foveal photoreceptor layer in eyes with CSC patients.
Feng Yan
Optical Coherence Tomography for Brain Imaging
Recently, there has been growing interest in using OCT for brain imaging. A feasibility study of OCT for guiding deep brain probes has found that OCT can differentiate the white matter and gray matter because the white matter tends to have a higher peak reflectivity and steeper attenuation rate compared to gray matter. In vivo 3D visualization of the layered organization of a rat olfactory bulb with OCT has been demonstrated. OCT has been used for single myelin fiber imaging in living rodents without labeling. The refractive index in the rat somatosensory cortex has also been measured with OCT. In addition, functional extension of OCT, such as Doppler-OCT (D-OCT), polarization sensitive-OCT (PS-OCT), and phase-resolved-OCT (PR-OCT), can image and quantify physiological parameters in addition to the morphological structure image. Based on the scattering changes during neural activity, OCT has been used to measure the functional activation in neuronal tissues. PS-OCT, which combines polarization sensitive detection with OCT to determine tissue birefringence, has been used for the localization of nerve fiber bundles and the mapping of micrometer-scale fiber pathways in the brain. D-OCT, also named optical Doppler tomography (ODT), combines the Doppler principle with OCT to obtain high resolution tomographic images of moving constituents in highly scattering biological tissues. D-OCT has been successfully used to image cortical blood flow and map the blood vessel network for brain research. In this chapter, the principle and technology of OCT and D-OCT are reviewed and examples of potential applications are described.
Liu, Gangjun; Chen, Zhongping
Optical Coherence Tomography of the Breast: A Feasibility Study.
Optical Coherence Tomography (OCT) is a new high-resolution imaging modality utilizing near-infrared light waves that can perform cross-sectional, real time, non-invasive images at or near the cellular level in tissue. Optical biopsies taken up to a depth...
J. L. Connolly L. Pantanowitz P. Herz S. Raza J. G. Fujimoto
Quantum optical coherence tomography of a biological sample
Quantum optical coherence tomography (QOCT) makes use of an entangled-photon light source to carry out dispersion-immune axial optical sectioning. We present the first experimental QOCT images of a biological sample: an onion-skin tissue coated with gold nanoparticles. 3D images are presented in the form of 2D sections of different orientations.
Nasr, Magued B; Nguyen, Nam; Rong, Guoxin; Yang, Linglu; Reinhard, Bjorn M; Saleh, Bahaa E A; Teich, Malvin C
An update on optical coherence tomography in dentistry.
An update and overview of the use of optical coherence tomography (OCT) in dentistry is described. Specific aspects discussed include the evolution of the technology and the basic process of light beam interference used to obtain OCT images. In addition, aspects of the optical properties of dentine and enamel and the range of current diagnostic applications of OCT in dentistry are reviewed. Clinical Relevance: The technique of optical coherence tomography is considered to be significant since the technology involved allows imaging using light to around 2-3 mm in teeth and can, for example, allow the extent and progression of carious lesions to be determined. PMID:24783887
Clarkson, D Mc G
Accuracy of optical navigation systems for automatic head surgery: optical tracking versus optical coherence tomography
The choice of a navigation system highly depends on the medical intervention and its accuracy demands. The most commonly used systems for image guided surgery (IGS) are based on optical and magnetic tracking systems. This paper compares two optical systems in terms of accuracy: state of the art triangulation-based optical tracking (OT) and optical coherence tomography (OCT). We use an experimental setup with a combined OCT and cutting laser, and an external OT. We simulate a robotic assisted surgical intervention, including planning, navigation, and processing, and compare the accuracies reached at a specific target with each navigation system.
D�az D�az, Jes�s; Riva, Mauro H.; Majdani, Omid; Ortmaier, Tobias
Ultrasound-modulated optical tomography at new depth
Ultrasound-modulated optical tomography (UOT) has the potential to reveal optical contrast deep inside soft biological tissues at an ultrasonically determined spatial resolution. The optical imaging depth reported so far has, however, been limited, which prevents this technique from broader applications. Our latest experimental exploration has pushed UOT to an unprecedented imaging depth. We developed and optimized a UOT system employing a photorefractive crystal-based interferometer. A large...
Lai, Puxiang; Xu, Xiao; Wang, Lihong V.
Imaging myocardial fiber orientation using polarization sensitive optical coherence tomography
Knowledge of myocardial fiber architecture is essential towards understanding heart functions. We demonstrated in this study a method to map cardiac muscle structure using the local optical axis obtained from polarization-sensitive optical coherence tomography (PSOCT). An algorithm was developed to extract the true local depth-resolved optical axis, retardance, and diattenuation from conventional round-trip results obtained in a Jones matrix-based PSOCT system. This method was applied to imag...
Fan, Chuanmao; Yao, Gang
Mapping distributed brain function and networks with diffuse optical tomography
Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted metal and electronic devices (for example, pacemakers). However, optical imaging technology has heretofore lacked the combination of spatial resolution and wide field of view sufficient to map distributed brain functions. Here, we present a high-density diffuse optical tomography imaging array that can map higher-order, distributed brain function. The system was tested by imaging four hierarchical language tasks and multiple resting-state networks including the dorsal attention and default mode networks. Finally, we imaged brain function in patients with Parkinson's disease and implanted deep brain stimulators that preclude functional magnetic resonance imaging.
Eggebrecht, Adam T.; Ferradal, Silvina L.; Robichaux-Viehoever, Amy; Hassanpour, Mahlega S.; Dehghani, Hamid; Snyder, Abraham Z.; Hershey, Tamara; Culver, Joseph P.
Optic disc topography of normal Indian eyes: An assessment using optical coherence tomography
Purpose: To study the optic disc topographic measurements of normal Indian eyes using optical coherence tomography (OCT). Materials and Methods: One hundred and fifty eyes selected randomly from 150 normal Indian subjects of both sex and various age groups underwent optic disc imaging with the OCT using the fast optic disc protocol. Results: Mean � standard deviation of the optic disc topographic measurements were: disc area 2.63 � 0.55 mm 2 ...
Dacosta Shaun; Bilal Sheena; Rajendran Babu; Janakiraman P
Polarization effect on the depth resolution of optical coherence tomography
We find for the first time that polarization mismatch of the sample and reference arms in optical-fiber-based optical coherence tomography (OCT) has critical effect on its depth resolution when the light source is partially polarized. When the polarization states of the two arms are matched, the measured point spread function (PSF) is almost identical to the theoretical prediction. When their polarization states are mismatched, the PSF can be so distorted that the depth resolution is degraded...
Jiao, Shuliang; Ruggeri, Marco
Noninvasive evaluation of retinal leakage using optical coherence tomography
Purpose: To demonstrate the association between changes in the blood-retinal barrier (BRB) identified by fluorescein leakage and those in the optical properties of the human retina determined by optical coherence tomography (OCT) and show how these changes can be quantified and their location identified within the retina. Methods: Two imaging techniques were applied: the retinal leakage analyzer, to map BRB function into intact or disrupted regions, and OCT, to measure refractive index change...
Bernardes, Rui; Santos, Torcato; Serranho, Pedro; Lobo, Conceic?a?o; Cunha-vaz, Jose?
Motion artifact suppression in full-field optical coherence tomography
Significant motion artifacts limit the performance of conventional full-field optical coherence tomography (FF-OCT) for in vivo imaging. We present a theoretical and experimental study of those limitations. A new FF-OCT system suppressing most of artifacts due to sample motions is demonstrated using instantaneous phase shifting with nonpolarizing optics and pulsed illumination. The experimental setup is based on a Linnik-type interferometer illuminated by the superluminescence emission from a...
Sacchet, Delphine; Brzezinski, Michal; Moreau, Julien; Dubois, Arnaud
Photons-based medical imaging - Radiology, X-ray tomography, gamma and positrons tomography, optical imaging
This book describes the different principles used in medical imaging. The detection aspects, the processing electronics and algorithms are detailed for the different techniques. This first tome analyses the photons-based techniques (X-rays, gamma rays and visible light). Content: 1 - physical background: radiation-matter interaction, consequences on detection and medical imaging; 2 - detectors for medical imaging; 3 - processing of numerical radiography images for quantization; 4 - X-ray tomography; 5 - positrons emission tomography: principles and applications; 6 - mono-photonic imaging; 7 - optical imaging; Index. (J.S.)
Application of optical longitudinal tomography for dental introscopy
A new method of dental introscopy in-vitro is suggested by the authors. This method implies the usage of longitudinal tomography techniques and is characterized by non-invasive and non-harmful diagnostics features, as well as interactive regime of image reconstruction which lets an operator (doctor) to control the diagnostics process in real time. He-Ne laser emission is used for obtaining of the projections. By the means of longitudinal tomography, images of different sections of an object (tooth) can be reconstructed. An experiment was held by the authors in which 100 projections of a tooth (premolar) were obtained and images of 10 different sections were reconstructed. These images were later compared to real sections of the tooth. This experiment proved that optical longitudinal tomography can be successfully used for dental introscopy. Authors claim that optical tomographic methods can be used for diagnostics of other biological objects as well. Such objects are characterized by spatial geometrical anisotropy (tubular bones, phalanxes of fingers, penis, etc.). It is especially promising to use this method for children's dentistry. the authors discuss some features of the data acquisition system for optical longitudinal tomography. Reconstruction algorithms are described. The results of experimental reconstruction are presented and advantages of this diagnostics method are discussed.
Levin, Gennady G.; Burgansky, Alexander A.; Levandovski, Alexei G.
Optical computed tomography liquid calibration phantom
Fluorinated ethylene propylene tubing is investigated as a method of preparing a contrast-resolution phantom for quantitative characterization of optical CT scanners and hydrogel dosimeters. Two sizes of tubing were examined: 6 and 13 mm inner diameter with 0.75 and 0.5 mm wall thicknesses, respectively. Water solutions of carbon black, nanoparticles in micelles provided continuously adjustable absorption contrast. Cross-sectional slices from two phantoms scanned with two different optical CT scanners are presented. Reconstructions from these simple phantoms can be used to identify scanner artefacts and improve instrument design. These phantoms represent a more reproducible approach than casting ''gel fingers'' into gel phantoms for system characterization. The thinner walled tubes have fewer optical artefacts.
Laser tomography adaptive optics: a performance study.
We present an analytical derivation of the on-axis performance of adaptive optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual error are given for cases of both continuous and discrete turbulent atmospheric profiles. Assuming Shack-Hartmann wavefront sensing with circular apertures, we demonstrate that the error is formally described by integrals of products of three Bessel functions. We compare the performance of adaptive optics correction when using natural, sodium, or Rayleigh laser guide stars. For small diameter class telescopes (?5 m), we show that a small number of Rayleigh beacons can provide similar performance to that of a single sodium laser, for a lower overall cost of the instrument. For bigger apertures, using Rayleigh stars may not be such a suitable alternative because of the too severe cone effect that drastically degrades the quality of the correction. PMID:24323009
Tatulli, Eric; Ramaprakash, A N
Investigation of pit formation in multilayer optical storage disks using optical coherence tomography
We propose anovel application of optical coherence tomography (OCT) to monitor pit formation in laser irradiated optical storage materials. A multilayer optical storage recordable compact disk, is composed of multiple layers, each of different structure. Disks were irradiated with a Q-Switched Nd:YAG laser with an energy of 373 mJ. Post-irradiated disks were evaluated by OCT and those images were compared with optical microscopy. Our results indicate that OCT is a useful instrument to investigate pit formation in mulitlayer optical storage disks and might also provide information to optimize optical memory technology.
Shin, Yongjin; Jung, Woonggyu; Chen, Zhongping; Nelson, John S.; Kim, Hyunjin; Park, Jinseong
Engineering of Nanoscale Contrast Agents for Optical Coherence Tomography
Optical coherence tomography has emerged as valuable imaging modalityin ophthalmology and other fields by enabling high-resolution three-dimensional imaging of tissue. In this paper, we review recent progress in the field of contrast-enhanced optical coherence tomography (OCT). We discuss exogenous and endogenous sources of OCT contrast, focusing on their use with standard OCT systems as well as emerging OCT-based imaging modalities. We include advances in the processing of OCT data that generate improved tissue contrast, including spectroscopic OCT (SOCT), as well as work utilizing secondary light sources and/or detection mechanisms to create and detect enhanced contrast, including photothermal OCT (PTOCT) and photoacoustic OCT (PAOCT). Finally, we conclude with a discussion of the translational potential of these developments as well as barriers to their clinical use.
Gordon, Andrew Y; Jayagopal, Ashwath
Congenital retinal macrovessel: atypical presentation using optical coherence tomography.
To describe a congenital retinal macrovessel with macular thickening. This case was investigated using fundus photography, fluorescein angiography, Spectralis optical coherence tomography and a 10-2 visual field test. A 23-year-old man was referred to our clinic with decreased vision in the right eye. Fundus examination of the right eye revealed a congenital retinal macrovessel that originated inferior to the superotemporal branch of the central retinal vein. Using fluorescein angiography, early filling and delayed emptying of the aberrant vein were observed. Spectralis optical coherence tomography demonstrated macular thickening and was supported by a 10-2 visual field test that revealed a relative scotoma corresponding to the same location. At the 18-month follow-up, visual acuity remained stable. Although rare, this case demonstrated that macular thickening can cause decreased visual acuity in the presence of a congenital retinal macrovessel. PMID:20922460
Ceylan, Osman M; Gullulu, Gulay; Akin, Tugrul; Bilen, Harun
Automated retinal pigment epithelium identification from optical coherence tomography images
Simple and robust method for identifying the retinal pigment epithelium (RPE) from optical coherence tomography images is demonstrated. At first, the maximum intensity value of each A-scans were determined and the depth position of those pixels are identified. The obtained 2D matrix is used as first estimation for the position of RPE. The erroneous pixel from the RPE is masked out and new approximation for them is calculated based on the neighbouring pixels. Finally, the obtained RPE matrix is smoothened. The RPE identification is used for separating the retina and choroid from optical coherence tomography images obtained by 830 nm spectral domain OCT. Both normal and ARMD patient eye were investigated to demonstrate the usability of that method. The calculation time for three dimensional data set (1024x450x137 pixels) was only 16 seconds and it identifies RPE reliably.
Fabritius, Tapio; Makita, Shuichi; Myllyl�, Risto; Yasuno, Yoshiaki
Motion estimation for cardiac emission tomography by optical flow methods
This paper describes a new method for estimating the 3D, non-rigid object motion in a time sequence of images. The method is a generalization of a standard optical flow algorithm that is incorporated into a successive quadratic approximation framework. The method was evaluated for gated cardiac emission tomography using images obtained from a mathematical, 4D phantom and a physical, dynamic phantom. The results showed that the proposed method offers improved motion estimation accuracy relative to the standard optical flow method. Convergence of the proposed algorithm was evidenced with a monotonically decreasing objective function value with iteration. Practical application of the motion estimation method in cardiac emission tomography includes quantitative myocardial motion estimation and 4D, motion-compensated image reconstruction
This paper describes a new method for estimating the 3D, non-rigid object motion in a time sequence of images. The method is a generalization of a standard optical flow algorithm that is incorporated into a successive quadratic approximation framework. The method was evaluated for gated cardiac emission tomography using images obtained from a mathematical, 4D phantom and a physical, dynamic phantom. The results showed that the proposed method offers improved motion estimation accuracy relative to the standard optical flow method. Convergence of the proposed algorithm was evidenced with a monotonically decreasing objective function value with iteration. Practical application of the motion estimation method in cardiac emission tomography includes quantitative myocardial motion estimation and 4D, motion-compensated image reconstruction.
Gilland, D R; Mair, B A; Parker, J G [University of Florida, Gainesville, FL 32605 (United States)], E-mail: email@example.com, E-mail: firstname.lastname@example.com, E-mail: email@example.com
Imaging tamoxifen retinopathy using spectral-domain optical coherence tomography
Full Text Available A case of tamoxifen retinopathy examined with spectral-domain optical coherence tomography (SD-OCT is presented. The typical refractile deposits are located between ganglion cell layer and inner plexiform layer in SD-OCT. A defect on the outer retinal layer with disruption of the photoreceptor layer with sharp edges is seen. The still attached posterior hyaloids gives evidence of other pathomechanism involved in the outer retinal defect than that of macular hole, as suggested in the literature.
Caramoy, Albert
Optical Coherence Tomography Imaging in Acute Coronary Syndromes
Optical coherence tomography (OCT) is a high-resolution imaging technique that offers microscopic visualization of coronary plaques. The clear and detailed images of OCT generate an intense interest in adopting this technique for both clinical and research purposes. Recent studies have shown that OCT is useful for the assessment of coronary atherosclerotic plaques, in particular the assessment of plaque rupture, erosion, and intracoronary thrombus in patients with acute coronary syndrome. In ...
Kubo, Takashi; Ino, Yasushi; Tanimoto, Takashi; Kitabata, Hironori; Tanaka, Atsushi; Akasaka, Takashi
The Use of Optical Coherence Tomography in Intraoperative Ophthalmic Imaging
Optical coherence tomography (OCT) has transformed diagnostic ophthalmic imaging but until recently has been limited to the clinic setting. The development of spectral-domain OCT (SD-OCT), with its improved speed and resolution, along with the development of a handheld OCT scanner, enabled portable imaging of patients unable to sit in a conventional tabletop scanner. This handheld SD-OCT unit has proven useful in examinations under anesthesia and, more recently, in intraoperative imaging of p...
Hahn, Paul; Migacz, Justin; O�connell, Rachelle; Maldonado, Ramiro S.; Izatt, Joseph A.; Toth, Cynthia A.
Multifocal Cysticercosis with Optical Coherence Tomography Findings in a Child
We herein report a case with multifocal cysticercosis � sub-conjunctival cysticercus cyst, sub-retinal cysticercosis, and neurocysticercosis in a child. The optical coherence tomography (OCT) findings of the sub-retinal cysticercus cyst are reported. He was treated with anti-helminthic drugs and oral prednisolone followed by surgical removal of the sub-retinal cyst. He subsequently underwent silicone oil removal with lens aspiration and intraocular lens implantation maintaining stable vision
Agarwal, Manisha; Jha, Vivek; Chaudhary, Somendra P.; Singh, Ashok K.
Optical coherence tomography-based micro-particle image velocimetry.
We present a new application of optical coherence tomography (OCT), widely used in biomedical imaging, to flow analysis in near-wall hydrodynamics for marine research. This unique capability, called OCT micro-particle image velocimetry, provides a high-resolution view of microscopic flow phenomena and measurement of flow statistics within the first millimeter of a boundary layer. The technique is demonstrated in a small flow cuvette and in a water tunnel. PMID:24322073
Mujat, Mircea; Ferguson, R Daniel; Iftimia, Nicusor; Hammer, Daniel X; Nedyalkov, Ivaylo; Wosnik, Martin; Legner, Hartmut
Intraoperative Evaluation of Breast Tumor Margins with Optical Coherence Tomography
As breast cancer screening rates increase, smaller and more numerous lesions are being identified earlier, leading to more breast-conserving surgical procedures. Achieving a clean surgical margin represents a technical challenge with important clinical implications. Optical coherence tomography (OCT) is introduced as an intraoperative high-resolution imaging technique that assesses surgical breast tumor margins by providing real-time microscopic images up to 2 mm beneath the tissue surface. I...
Nguyen, Freddy T.; Zysk, Adam M.; Chaney, Eric J.; Kotynek, Jan G.; Oliphant, Uretz J.; Bellafiore, Frank J.; Rowland, Kendrith M.; Johnson, Patricia A.; Boppart, Stephen A.
Diffuse optical tomography with physiological and spatial a priori constraints
Diffuse optical tomography is a typical inverse problem plagued by ill-condition. To overcome this drawback, regularization or constraining techniques are incorporated in the inverse formulation. In this work, we investigate the enhancement in recovering functional parameters by using physiological and spatial a priori constraints. More accurate recovery of the two main functional parameters that are the blood volume and the relative saturation is demonstrated through simulations by using our method compared to actual techniques. (note)
Intes, Xavier [Department of Biophysics and Biochemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Maloux, Clemence [Department of Biophysics and Biochemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Guven, Murat [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Yazici, Birzen [Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Chance, Britton [Department of Biophysics and Biochemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States)
Imaging Natural Occlusal Caries Lesions with Optical Coherence Tomography
Several studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can be used to nondestructively measure the severity of demineralization in the important occlusal surfaces. The purpose of this study was to assess the potential of PS-OCT and OCT methods for the measurement of the depth of natural occlusal carious lesions. Teeth were screened for potential occlusal lesions using near infrared imaging (NIR). A PS-OCT system operating at 1310-nm was used to acq...
Quantification of cardiac fiber orientation using optical coherence tomography
Heterogeneity in cardiac tissue microstructure is a potential mechanism for the generation and maintenance of arrhythmias. Abnormal changes in fiber orientation increase the likelihood of arrhythmia. We present optical coherence tomography (OCT) as a method to image myofibers in excised intact heart preparations. Three-dimensional (3-D) image sets were gathered from the rabbit right ventricular free wall (RVFW) using a microscope-integrated OCT system. An automated algorithm for fiber orienta...
Fleming, Christine P.; Ripplinger, Crystal M.; Webb, Bryan; Efimov, Igor R.; Rollins, Andrew M.
Corneal topography from spectral optical coherence tomography (sOCT)
We present a method to obtain accurate corneal topography from a spectral optical coherence tomography (sOCT) system. The method includes calibration of the device, compensation of the fan (or field) distortion introduced by the scanning architecture, and image processing analysis for volumetric data extraction, segmentation and fitting. We present examples of three-dimensional (3-D) surface topography measurements on spherical and aspheric lenses, as well as on 10 human corneas in vivo. Resu...
Ortiz, Sergio; Siedlecki, Damian; Pe?rez Merino, Pablo; Chia, Noelia; Castro, Alberto; Szkulmowski, Maciej; Wojtkowski, Maciej; Marcos, Susana
Recovery of piecewise constant coefficients in optical diffusion tomography
In optical diffusion tomography the reconstruction of the absorbtion and scattering coefficients is conventionally carried out in a pixel basis. The resulting number of unknowns makes the associated inverse problem severely ill-posed. We have recently proposed a new approach in which the goal is to reconstruct boundaries of piecewise constant tissue regions as well as the diffusion and absorption coefficients within these regions. This method assumes that there is a feasible initial guess on ...
Multiple scattering in wide-field optical coherence tomography
Optical Coherence Tomography (OCT), a well-established imaging method based on low-coherence interferometry, provides cross-sectional images of the internal structure of biological samples with a resolution in the micrometer range. OCT was successfully applied on various tissues such as for instance the retina, the skin or a tooth. In highly scattering tissues like the skin, probing depth is limited to approximately 2mm, mainly due to insufficient rejection of multiply scattered light. Presen...
Karamata, Boris
Optical coherence tomography classification of diabetic cystoid macular edema
Yasser M Helmy, Heba R Atta AllahDepartment of Ophthalmology, Minia University, Minya, EgyptPurpose: To propose a new classification of diabetic cystoid macular edema (CME) based on optical coherence tomography (OCT) findings and cover all new important findings.Patients and methods: A retrospective study was carried out in the El-Minia Investigation Eye Center between January 2012 and November 2012. It included 104 eyes of 86 patients, aged between 50 and 71 years, all with type II diabetes ...
Cancellation of coherent artifacts in optical coherence tomography imaging
Coherent artifacts in optical coherence tomography (OCT) images can severely degrade image quality by introducing false targets if no targets are present at the artifact locations. Coherent artifacts can also add constructively or destructively to the targets that are present at the artifact locations. This constructive or destructive interference will result in cancellation of the true targets or in display of incorrect echo amplitudes of the targets. We introduce the use of a nonlinear deco...
Piao, Daqing; Zhu, Quing; Dutta, Niloy K.; Yan, Shikui; Otis, Linda L.
Phase-locked Fourier domain optical coherence tomography
Fourier or spectral domain optical coherence tomography (FDOCT) is a multi-dimensional interferometric imaging modality that has attracted increasing interest during the last few years. The reason is its outstanding sensitivity allowing high speed 2D and 3D imaging of weakly backscattering biological tissues in vivo and with high axial resolution. FDOCT has today largely replaced the preceding time domain OCT due to its marked advantage in sensitivity and acquisition speed. In particular, for...
Clinical optical coherence tomography combined with multiphoton tomography for evaluation of several skin disorders
The first clinical trial of optical coherence tomography (OCT) combined with multiphoton tomography (MPT) and dermoscopy is reported. State-of-the-art (i) OCT systems for dermatology (e.g. multibeam swept source OCT), (ii) the femtosecond laser multiphoton tomograph DermaInspectTM, and (iii) digital dermoscopes were applied to 47 patients with a diversity of skin diseases and disorders such as skin cancer, psoriasis, hemangioma, connective tissue diseases, pigmented lesions, and autoimmune bullous skin diseases. Dermoscopy, also called 'epiluminescent microscopy', provides two-dimensional color images of the skin surface. OCT imaging is based on the detection of optical reflections within the tissue measured interferometrically whereas nonlinear excitation of endogenous fluorophores and the second harmonic generation are the bases of MPT images. OCT cross sectional "wide field" image provides a typical field of view of 5 x 2 mm2 and offers fast information on the depth and the volume of the investigated lesion. In comparison, multiphoton tomography presents 0.36 x 0.36 mm2 horizontal or diagonal sections of the region of interest within seconds with submicron resolution and down to a tissue depth of 200 ?m. The combination of OCT and MPT provides a synergistic optical imaging modality for early detection of skin cancer and other skin diseases.
K�nig, Karsten; Speicher, Marco; B�ckle, Rainer; Reckfort, Julia; McKenzie, Gordon; Welzel, Julia; Koehler, Martin J.; Elsner, Peter; Kaatz, Martin
Jade detection and analysis based on optical coherence tomography images
Optical coherence tomography is a fundamentally new type of optical sensing technology that can perform high-resolution, cross sectional sensing of the internal structure of materials and biological samples. This work briefly describes its capability of exploring and analyzing the internal structures and textures of various jades. With a depth resolution of 4 ?m in jade and penetration range of 5 mm in jade, swept-source OCT could be used as a new powerful instrument to generate 3-D volume data of jade, which is important for applications in jade industry and artwork, particularly for jade detection and classification, counterfeit recognition, and guided artistic carving.
Apparatus is described for generating a two-dimensional back-projected image of a slice of an object in tomography. The apparatus uses optical techniques to perform the functions of filtering and back projection. Central to the technique is a cylindrical drum which rotates at a fast rate and whose rotational axis tilts at a slower rate. The novel method overcomes the problem of image blurring due to motion which occurs in many tomographic techniques. It also has the advantages of being less expensive and simpler compared to tomography using digital processing techniques which require fast computers. (UK)
Abstract. Ultrasound-modulated optical tomography (UOT) has the potential to reveal optical contrast deep inside soft biological tissues at an ultrasonically determined spatial resolution. The optical imaging depth reported so far has, however, been limited, which prevents this technique from broader applications. Our latest experimental exploration has pushed UOT to an unprecedented imaging depth. We developed and optimized a UOT system employing a photorefractive crystal-based interferometer. A large aperture optical fiber bundle was used to enhance the efficiencies for diffuse light collection and photorefractive two-wave-mixing. Within the safety limits for both laser illumination and ultrasound modulation, the system has attained the ability to image through a tissue-mimicking phantom of 9.4�cm in thickness, which has never been reached previously by UOT.
Optical tomography of pigmented human skin biopsies
The novel femtosecond NIR (near infrared) laser based high resolution imaging system DermaInspect was used for non-invasive diagnostics of pigmented skin. The system provides fluorescence and SHG images of high spatial submicron resolution (3D) and 250 ps temporal resolution (4D) based on time resolved single photon counting (TCSPC). Pigmented tissue biopsies from patients with nevi and melanoma have been investigated using the tunable 80 MHz femtosecond laser MaiTai with laser wavelengths in the range of 750 - 850 nm. The autofluorescence patterns of different intratissue cell types and structures were determined. The non-linear induced autofluorescence originates from naturally endogenous fluorophores and protein structures like NAD(P)H, flavins, elastin, collagen, phorphyrins and melanin. In addition to autofluorescence, SHG (second harmonic generation) was used to detect dermal collagen structures. Interestingly, pigmented cells showed intense luminescence signals. Further characterization of tissue components was performed via 4D measurements of the fluorescence lifetime (x, y, z, ?). The novel multiphoton technique offers the possibility of a painless high resolution non invasive diagnostic method (optical biopsy), in particular for the early detection of skin cancer.
Riemann, Iris; Fischer, Peter; Kaatz, Martin; Fischer, Tobias W.; Elsner, Peter; Dimitrov, Enrico; Reif, Annette; Konig, Karsten
Optical Coherence Tomography: Modeling and Applications
DEFF Research Database (Denmark)
An analytical model is presented that is able to describe the performance of OCT systems in both the single and multiple scattering regimes simultaneously. This model inherently includes the shower curtain effect, well-known for light propagation through the atmosphere. This effect has been omitted in previous theoretical models of OCT systems. It is demonstrated that the shower curtain effect is of utmost importance in the theoretical description of an OCT system. The analytical model, together with proper noise analysis of the OCT system, enables calculation of the SNR, where the optical properties of the tissue are taken into account. Furthermore, by using the model, it is possible to determine the lateral resolution of OCT systems at arbitrary depths in the scattering tissue. During the Ph.D. thesis project, an OCT system has been constructed, and the theoretical model is verified experimentally using this system. A demonstration of the imaging capabilities of the OCT system is given. Moreover, a novel truereflection OCT imaging algorithm, based on the new OCT model presented in this thesis, is demonstrated. Finally, a theoretical analysis of the Wigner phase-space distribution function for the OCT geometry, i.e., reflection geometry, is developed. As in the new OCT model, multiple scattered photons has been taken into account together with multiple scattering effects. As an important result, a novel method of creating images based on measurements of the momentum width of the Wigner phase-space distribution is presented, and compared with conventional OCT.
Thrane, Lars
A Review on the use of Optical Coherence Tomography in Medical Imaging
Full Text Available Optical Coherence Tomography (OCT is a Three-dimensional imaging technique with ultrahigh spatial resolution even in highly scattering media. It is based on measurements of the reflected light from tissue discontinuities. Optical coherence tomography delivers high resolution images, because the test is based on light, rather than sound or radio frequency. Optical coherence tomography provides a 1 to 15 �m resolution but only a depth of 1 to 2 mm can be imaged in opaque tissues such as arteries or skin. In transparent tissues such as the eye, greater imaging depths are possible. In addition, optical coherence tomography is capable of providing information about tissue composition. This paper, aims at reviewing the working principle of Optical Coherence Tomography and the quality of the image produced through this technique. A major drawback of Optical Coherence Tomography image is that, it suffers from speckle noise.
A. Stella
Speckle contrast optical tomography: A new method for deep tissue three-dimensional tomography of blood flow
A novel tomographic method based on the laser speckle contrast, speckle contrast optical tomography (SCOT) is introduced that allows us to reconstruct three dimensional distribution of blood flow in deep tissues. This method is analogous to the diffuse optical tomography (DOT) but for deep tissue blood flow. We develop a reconstruction algorithm based on first Born approximation to generate three dimensional distribution of flow using the experimental data obtained from tissue simulating phantoms.
Varma, Hari M.; Valdes, Claudia P.; Kristoffersen, Anna K.; Culver, Joseph P.; Durduran, Turgut
A Low-Cost Method for Optical Tomography
Full Text Available INTRODUCTION: In this study, arrangement of a low-cost optical tomography device compared to other methods such as frequency domain diffuse tomography or time domain diffuse tomography is reported. This low-cost diffuse optical imaging technique is based on the detection of light after propagation in tissue. These detected signals are applied to predict the location of in-homogeneities inside phantoms. The device is assessed for phantoms representing homogenous healthy breast tissues as well as those representing healthy breast tissues with a lesion inside.METHODS: A diode laser at 780nm and 50 mW is used as the light source. The scattered light is then collected from the outer surface of the phantom by a detector. Both laser and detector are fiber coupled. The detector fiber may turn around the phantom to collect light scattered at different angles. Phantoms made of intralipid as the scattering medium and ink as the absorbing medium are used as samples. Light is collected after propagation in the phantoms and the capability of the device in collecting data and detecting lesions inside the phantoms is assessed. The fact that the detection fiber orbits around the sample and detects light from various angles has eliminated the need to use several detectors and optical fibers. The results obtained from experiments are compared with the results obtained from a finite element method (FEM solution of diffusion equation in cylindrical geometry written in FORTRAN.RESULTS: The graphs obtained experimentally and numerically are in good accordance with each other. The device has been able to detect lesions up to 13 mm inside the biological phantom.CONCLUSION: The data achieved by the optical tomography device is compared with the data achieved via a FEM code written in FORTRAN. The results indicate that the presented device is capable of providing the correct pattern of diffusely backscattered and transmitted light. The data achieved from the device is in excellent correlation with the numerical solution of the diffusion equation. Therefore, results indicate the applicability of the reported device. This device may be used as a base for an optical imaging. It is also capable of detecting lesions inside the phantoms
Mohammad Ali Ansari
Pilot Study of Optical Coherence Tomography Measurement of Retinal Blood Flow in Retinal and Optic Nerve Diseases
A new method of retinal blood flow measurement using Doppler optical coherence tomography was developed. It showed circulatory abnormalities in retinal and optic nerve diseases that correlated with disease location and severity.
Wang, Yimin; Fawzi, Amani A.; Varma, Rohit; Sadun, Alfredo A.; Zhang, Xinbo; Tan, Ou; Izatt, Joseph A.; Huang, David
Research progress on anterior segment optical coherence tomography in glaucoma
Full Text Available Glaucoma is the second blindness disease in the world, and there are more primary angle closed glaucoma in China. The anatomy changes of the anterior chamber have close relationships with the development of glaucoma. Anterior segment optical coherence tomography(AS-OCThas the advantages of fast, non-contact, high resolution and accurate quantitative measurement, which provides a kind of important method for finding the pathogenesis of primary angle closed glaucoma, for early diagnosis and treatment of glaucoma, and for the postoperative evaluation of glaucoma.
Li Zhao
Clinical diagnosis of oral submucous fibrosis with optical coherence tomography
A swept-source optical coherence tomography (SS-OCT) system with a specially designed probe is built for clinical scanning of oral submucous fibrosis (OSF) patients. By analysing 44 OSF cases of SS-OCT scanning results, two indicators, including epithelium (EP) thickness and standard deviation (SD) of A-mode scan intensity in the laminar propria (LP) layer, are found useful for real-time OSF diagnosis. Statistics show that sensitivity and specificity of LP SD can reach 84.1 and 95.5 %, respectively. Also, both sensitivity and specificity of EP thickness can reach 100 %.
Lee, Cheng-Kuang; Tsai, Meng-Tsan; Yang, C. C.; Chiang, Chun-Pin
Thermal-light full-field optical coherence tomography
We have built a high-resolution optical coherence tomography (OCT) system, based on a Linnik-type interference microscope, illuminated by a white-light thermal lamp. The extremely short coherence length of the illumination source and the large aperture of the objectives permit resolution close to 1 mm in three dimensions. A parallel detection scheme with a CCD camera provides cross-section x y image acquisition without scanning at a rate of up to 50 Hz. To our knowledge, our system has the hi...
Frequency comb swept lasers for optical coherence tomography
We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the cavity of swept lasers causes the lasers to generate a series of well defined frequency steps. The na...
Tsai, Tsung-han; Zhou, Chao; Adler, Desmond C.; Fujimoto, James G.
[Optical coherence tomography in the imaging of the iridocorneal angle].
Anterior segment optical coherence tomography (AS OCT), enables visualization and measurements of the anterior segment of the eye. In particular, it is a valuable tool in the imaging of the iridocorneal angle. In this paper, we reviewed parameters used for analysis of the iridocorneal angle in AS OCT and compared changes of these parameters after cataract surgery, laser iridotomy and illumination. Special attention was paid to changes of such quantitative parameters as TISA (trabecular-iris space area), AOD (angle opening distance), and ARA (angle recess area). PMID:21853957
Drzyzga, ?ukasz; Mrukwa-Kominek, Ewa; Mielniczuk, Ewa; Romaniuk, Wanda
Clinical manifestations of optic pit maculopathy as demonstrated by spectral domain optical coherence tomography
Jonathan H Tzu, Harry W Flynn Jr, Audina M Berrocal, William E Smiddy, Timothy G Murray, Yale L FisherDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USAPurpose: The purpose of this retrospective study was to evaluate the characteristic features, including spectral-domain optical coherence tomography (SD-OCT), clinical course, and outcome of treatment if given for patients with optic disc pit maculopathy.Methods: We investiga...
Jh, Tzu; Hw, Flynn Jr; Am, Berrocal; We, Smiddy; Tg, Murray; Yl, Fisher
Ultrasound modulated optical tomography in optical diffuse medium using acoustic radiation force
Ultrasound modulated optical tomography (UOT) is a hybrid technique which combines optical contrast with ultrasound (US) resolution to achieve deeper tissue imaging. However, the technique is currently limited due to the weak modulation signal strength and consequently a low Signal-to-Noise Ratio (SNR). One potential way to increase the SNR of UOT is to increase the ultrasound induced particle displacement, by either increasing the ultrasound amplitude or using the acoustic radiation force (A...
Li, Rui
Compensation of motion artifacts in intracoronary optical frequency domain imaging and optical coherence tomography
Intracoronary optical coherence tomography and optical frequency domain imaging (OFDI) have been utilized for two-dimensional and three-dimensional imaging of vascular microanatomy. Image quality and the spatial accuracy of multidimensional reconstructions, however, can be degraded due to artifacts resulting from relative motion between the intracoronary catheter and the vessel wall. To track the relative motion of a catheter with regard to the vessel, a motion tracking system was incorporate...
Ha, Jinyong; Yoo, Hongki; Tearney, Guillermo J.; Bouma, Brett E.
Extending the effective imaging range of Fourier domain optical coherence tomography using a fiber optic switch
The effective imaging range of Fourier-domain optical coherence tomography is limited by fall-off. We present a very simple method to extend the effective imaging range with dual reference arms and a high speed fiber optic switch. The effective imaging range was increased by 1.8 with two reference arms compared with a single reference arm. Ex vivo tissue images showed significantly improved sensitivity over a large imaging range. Further extension of the imaging range is feasible with multipl...
Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy1
Optical coherence tomography (OCT) is an emerging technology for performing high-resolution cross-sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross-sectional images of tissue structure on the micron scale in situ and in real time. Using OCT in combination with catheters and endoscopes enables high-resolution intraluminal imaging of organ systems. OCT can function as a type of optical biopsy and is a powerful imaging te...
Fujimoto, James G.; Pitris, Costas; Boppart, Stephen A.; Brezinski, Mark E.
Characterizing matrix remodeling in collagen gels using optical coherence tomography
Optical coherence tomography (OCT) has shown promise at non-destructively characterizing engineered tissues such as collagen gels. However, as the collagen gels develop, the OCT images lose contrast of structures as the gels develop, making visual assessment difficult. Our group proposed quantitatively characterizing these gels by fitting the optical properties from the OCT signals. In this paper, we imaged collagen gels seeded with smooth muscle cells (SMCs) over a 5-day period and used the data to measure their optical properties. Our results showed that over time, the reflectivity of the samples increased 10-fold, corresponding to a decrease in anisotropy factor g, without much change in the scattering coefficient ?s. Overall, the optical properties appeared to be dominated by scattering from the collagen matrix, not the cells. However, SMCs remodeled the collagen matrix, and this collagen remodeling by the cells is what causes the observed changes in optical properties. Moreover, the data showed that the optical properties were sensitive to the activity of matrix metalloproteinases (MMPs), enzymes that break down local collagen fibrils into smaller fragments. Blocking MMPs in the SMC gels greatly impeded both the remodeling process and change in optical properties at day 5. Treating day 1 acellular gels with MMP-8 for 3 hr managed to partially reproduce the remodeling observed in SMC gels at day 5. Altogether, we conclude that matrix remodeling in general, and MMPs specifically, greatly affect the local optical properties of the sample, and OCT is a unique tool that can assess MMP activity in collagen gels both non-destructively and label free.
Levitz, David; Hinds, Monica T.; Hanson, Stephen R.; Jacques, Steven L.
Diffuse optical tomography with a priori anatomical information
Diffuse optical tomography (DOT) poses a typical ill-posed inverse problem with a limited number of measurements and inherently low spatial resolution. In this paper, we propose a hierarchical Bayesian approach to improve spatial resolution and quantitative accuracy by using a priori information provided by a secondary high resolution anatomical imaging modality, such as magnetic resonance (MR) or x-ray. In such a dual imaging approach, while the correlation between optical and anatomical images may be high, it is not perfect. For example, a tumour may be present in the optical image, but may not be discernable in the anatomical image. The proposed hierarchical Bayesian approach allows incorporation of partial a priori knowledge about the noise and unknown optical image models, thereby capturing the function-anatomy correlation effectively. We present a computationally efficient iterative algorithm to simultaneously estimate the optical image and the unknown a priori model parameters. Extensive numerical simulations demonstrate that the proposed method avoids undesirable bias towards anatomical prior information and leads to significantly improved spatial resolution and quantitative accuracy
Diffuse optical tomography (DOT) poses a typical ill-posed inverse problem with a limited number of measurements and inherently low spatial resolution. In this paper, we propose a hierarchical Bayesian approach to improve spatial resolution and quantitative accuracy by using a priori information provided by a secondary high resolution anatomical imaging modality, such as magnetic resonance (MR) or x-ray. In such a dual imaging approach, while the correlation between optical and anatomical images may be high, it is not perfect. For example, a tumour may be present in the optical image, but may not be discernable in the anatomical image. The proposed hierarchical Bayesian approach allows incorporation of partial a priori knowledge about the noise and unknown optical image models, thereby capturing the function-anatomy correlation effectively. We present a computationally efficient iterative algorithm to simultaneously estimate the optical image and the unknown a priori model parameters. Extensive numerical simulations demonstrate that the proposed method avoids undesirable bias towards anatomical prior information and leads to significantly improved spatial resolution and quantitative accuracy.
Guven, Murat [Electrical, Computer, and Systems Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States); Yazici, Birsen [Electrical, Computer, and Systems Engineering Department, Rensselaer Polytechnic Institute, Troy, NY (United States); Intes, Xavier [Department of Biophysics and Biochemistry, University of Pennsylvania, Philadelphia, PA (United States); Chance, Britton [Department of Biophysics and Biochemistry, University of Pennsylvania, Philadelphia, PA (United States)
Performance of latex balloons for optical computed tomography
Latex balloons filled with radiation sensitive hydrogels were evaluated as 3D dosimeters with optical computed tomography (CT) readout. Custom balloons, with less than 10 cm diameters, were made from latex sheets. Commercial, 13 cm diameter, clear balloons were investigated for larger volumes. Ferrous-xylenol orange and genipin gelatin gels selected for 1 and 30 Gy experiments, respectively. The thin stretched latex membrane allowed optical imaging to within 1 mm of the interior balloon edge. Reconstructed dose distributions demonstrated valid measurements to within 2 mm of the balloon surface. The rubber membrane provides a hybrid approach to deforming hydrogels. Uniform irradiation of a deformed gel resulted in a uniform dose being measured when scanned in the relaxed, initial balloon shape. The 13 cm diameter balloons were also effective and inexpensive vessels for hydrogels due to their high clarity, thinness and mechanical strength. Latex balloons represent an inexpensive method to obtain useful information from nearly the entire dosimeter volume.
Jordan, K.; Walsh, A.; Peng, M.; Battista, J.
Imaging of oral pathological tissue using optical coherence tomography
Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images. The elements obserced included extensive epithelial down-growth, the disruption of the basement membrane, with areas of erosion, an epithelial layer that was highly variable in thickness and invasion into the sub-epithelial layers. Therefore, OCT appears to be a highly promising imaging modality.
Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.
Non-diffusing photochromic gel for optical computed tomography phantoms
This study examines photochromic response in radiation sensitive hydrogels. Genipin, crosslinked, gelatin gel can support high resolution images because the chromophores do not diffuse. A low power, 633 nm He-Ne laser was used to write lines into the gels by a photobleaching reaction. Optical cone-beam computed tomography (CBCT) scans mapped the high resolution images in 3D with 0.25 mm voxel resolution. A straight line was written into a deformed gel and then readout in its relaxed, initial shape. The curved, photo-bleached line demonstrated deformable 3D dosimetry is possible with this system to the balloon edge. High resolution, photochromic images provide key information for characterizing optical CT scanners and 3D dosimeters. Many, ionizing radiation, dosimeter materials demonstrate either a photochromic or photothermal response, allowing this approach to be widely used in quantitative 3D scanning.
Jordan, K.
Sound field reconstruction using acousto-optic tomography
When sound propagates through a medium, it results in pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the refractive index that characterizes the propagation of light is not constant, but influenced by the acoustic field. This kind of interaction is known as the acousto-optic effect. The formulation of this physical phenomenon into a mathematical problem can be described in terms of the Radon transform, which makes it possible to reconstruct an arbitrary sound field using tomography. The present work derives the fundamental equations governing the acousto-optic effect in air, and demonstrates that it can be measured with a laser Doppler vibrometer in the audible frequency range. The tomographic reconstruction is tested by means of computer simulations and measurements. The main features observed in the simulations are also recognized in the experimental results. The effectiveness of the tomographic reconstruction is further confirmed with representations ofthe very same sound field measured with a traditional microphone array.
Torras Rosell, Antoni; Barrera Figueroa, Salvador
Multiple delay lines full-field optical coherence tomography
Full-field Optical Coherence Tomography (FF-OCT) is a parallel detection OCT technique using a 2D detector array. This technique avoids mechanical scanning in imaging optics. Therefore, it can speed up the imaging process and enhance the imaging quality. We present a FF-OCT instrument to be used in conjunction with the principle of multiple delays (MD) OCT to evaluate the topography of curved objects in a single-shot imaging. We evaluate the optimum combination of the MD principle with the FF-OCT method and measure the radius of a metal ball with this method. We managed to obtain 2n-1 contour lines using an MDE with n delays in a single en-face OCT image to evaluate the curvature of the object surface.
Wang, Jingyu; Dainty, Christopher; Podoleanu, Adrian G.
Endoscopic optical coherence tomography for imaging the tympanic membrane
Optical coherence tomography (OCT) is an imaging modality that enables micrometer-scale contactless subsurface imaging of biological tissue. Endoscopy, as another imaging method, has the potential of imaging tubular organs and cavities and therefore has opened up several application areas not accessible before. The combination of OCT and endoscopy uses the advantages of both methods and consequently allows additional imaging of structures beneath surfaces inside cavities. Currently, visual investigations on the surface of the human tympanic membrane are possible but only with expert eyes. up to now, visual imaging of the outer ear up to the tympanic membrane can be carried out by an otoscope, an operating microscope or an endoscope. In contrast to these devices, endoscopy has the advantage of imaging the whole tympanic membrane with one view. The intention of this research is the development of an endoscopic optical coherence tomography (EOCT) device for imaging the tympanic membrane depth-resolved and structures behind it. Detection of fluids in the middle ear, which function as an indicator for otitis media, could help to avoid the application of antibiotics. It is possible to detect a congeries of fluids with the otoscope but the ambition is to the early detection by OCT. The developed scanner head allows imaging in working distances in the range from zero up to 5 mm with a field of view of 2 mm. In the next step, the scanner head should be improved to increase the working distance and the field of view.
Burkhardt, Anke; Walther, Julia; Cimalla, Peter; Bornitz, Matthias; Koch, Edmund
Endoscopic Bio-Imaging Using Optical Coherence Tomography
Optical coherence tomography(OCT) is an emerging medical diagnostic tool that draws great attention in medical and biological fields. It has a 10-100 times higher spatial resolution than that of the clinical ultrasound but lower imaging depth such as 1-2 mm. In order to image internal organs, OCT needs an endoscopic probe. In this paper, the principle of Fourier-domain optical coherence tomography with high-speed imaging capability was introduced. An OCT endoscope based on MEMS technology was developed. It was attached to the Fourier-domain OCT system to acquire three-dimensional tomographic images of gastrointestinal tract of New Zealand white rabbit. The endoscope had a two-axis scanning mirror that was driven by electrostatic force. The mirror stirred an incident light to sweep two-dimensional plane by scanning. The outer diameter of the endoscope was 6 mm and the mirror diameter was 1.2 mm. A three-dimensional image rendered by 200 two-dimensional tomographs with 200x500 pixels was displayed within 3.5 seconds. The spatial resolution of the OCT system was 8 ?m in air
Optical coherence tomography(OCT) is an emerging medical diagnostic tool that draws great attention in medical and biological fields. It has a 10-100 times higher spatial resolution than that of the clinical ultrasound but lower imaging depth such as 1-2 mm. In order to image internal organs, OCT needs an endoscopic probe. In this paper, the principle of Fourier-domain optical coherence tomography with high-speed imaging capability was introduced. An OCT endoscope based on MEMS technology was developed. It was attached to the Fourier-domain OCT system to acquire three-dimensional tomographic images of gastrointestinal tract of New Zealand white rabbit. The endoscope had a two-axis scanning mirror that was driven by electrostatic force. The mirror stirred an incident light to sweep two-dimensional plane by scanning. The outer diameter of the endoscope was 6 mm and the mirror diameter was 1.2 mm. A three-dimensional image rendered by 200 two-dimensional tomographs with 200x500 pixels was displayed within 3.5 seconds. The spatial resolution of the OCT system was 8 {mu}m in air.
Ahn, Yeh Chan; Brenner, Matthew; Chen, Zhongping [Pukyong Nationanl University, Busan (Korea, Republic of)
Analysis of multiple scattering effects in optical Doppler tomography
Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth-resolved retinal flow profiles where the influence of multiple scattering was observed [Yazdanfar et al., Opt. Lett. 25, 1448 (2000)]. To the best of our knowledge, no analytical model exists that are able to explain these observations.
Thrane, L.; Andersen, Peter E.
Macular optical coherence tomography findings following blunt ocular trauma
Full Text Available Dilys Oladiwura,1 Lik Thai Lim,1 Elliott Yann Ah-kee,2 James Angus Scott31Tennent Institute of Ophthalmology, Gartnavel General Hospital (NHS Greater Glasgow and Clyde Trust, Glasgow, UK; 2University of Glasgow, Glasgow, UK; 3Falkirk Community Hospital (Forth Valley NHS Trust, Falkirk, UKAbstract: This case report describes the optical coherence tomography (OCT results of Berlin�s edema in a male subject following blunt ocular trauma from a soccer ball. A�27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after�3�months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlin�s edema secondary to blunt ocular trauma because Berlin�s edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye.Keywords: Berlin�s edema, commotio retinae, optical coherence tomography, OCT, ocular trauma
Oladiwura D
Parallel multithread computing for spectroscopic analysis in optical coherence tomography
Spectroscopic Optical Coherence Tomography (SOCT) is an extension of Optical Coherence Tomography (OCT). It allows gathering spectroscopic information from individual scattering points inside the sample. It is based on time-frequency analysis of interferometric signals. Such analysis requires calculating hundreds of Fourier transforms while performing a single A-scan. Additionally, further processing of acquired spectroscopic information is needed. This significantly increases the time of required computations. During last years, application of graphical processing units (GPU's) was proposed to reduce computation time in OCT by using parallel computing algorithms. GPU technology can be also used to speed-up signal processing in SOCT. However, parallel algorithms used in classical OCT need to be revised because of different character of analyzed data. The classical OCT requires processing of long, independent interferometric signals for obtaining subsequent A-scans. The difference with SOCT is that it requires processing of multiple, shorter signals, which differ only in a small part of samples. We have developed new algorithms for parallel signal processing for usage in SOCT, implemented with NVIDIA CUDA (Compute Unified Device Architecture). We present details of the algorithms and performance tests for analyzing data from in-house SD-OCT system. We also give a brief discussion about usefulness of developed algorithm. Presented algorithms might be useful for researchers working on OCT, as they allow to reduce computation time and are step toward real-time signal processing of SOCT data.
Trojanowski, Michal; Kraszewski, Maciej; Strakowski, Marcin; Pluci?ski, Jerzy
In-situ imaging of articular cartilage of the first carpometacarpal joint using co-registered optical coherence tomography and computed tomography
Conventional imaging modalities are unable to depict the early degeneration of articular cartilage in osteoarthritis, especially in small joints. Optical coherence tomography has previously been used successfully in high-resolution imaging of cartilage tissue. This pilot cadaver study demonstrates the use of intra-articular optical coherence tomography in imaging of articular cartilage of the first carpometacarpal joint, producing high resolution images of the articular surface in which cartilage thickness and surface characteristics were assessed. Findings on optical coherence tomography were confirmed with histology. Furthermore, co-registration of optical coherence tomography and computed tomography was used to accurately determine the scanned trajectory and reconstruct a true-scale image overlay.
Cernohorsky, Paul; de Bruin, Daniel M.; van Herk, Marcel; Bras, Johannes; Faber, Dirk J.; Strackee, Simon D.; van Leeuwen, Ton G.
Adaptive Optics Optical Coherence Tomography Based on a 61-Element Deformable Mirror
When optical coherence tomography (OCT) is used to image human retina, its lateral resolution is deteriorated by the aberrations of the human eye. To get over this disadvantage, a high-resolution imaging system combining OCT with adaptive optics (AO) is being developed. The AO system consists of a 61-element deformable mirror and a 16x16 array Shack-Hartmann wave front sensor. In this paper, the configuration of the AO/OCT system is described, the simulation comparison among the 19-, 37- and 61-element adaptive optics systems and the experiment results for OCT with opened-loop AO are presented
Pulsed ultrasound-modulated optical tomography using spectral-hole burning as a narrowband spectral filter
We applied a submegahertz nonlinear optical filter afforded by a cryogenically cooled spectral-hole burning crystal to ultrasound-modulated optical tomography. Our experimental results show that this technique, having the largest etendue among all available ultrasound-modulated optical tomography techniques and being immune to speckle decorrelation, offers potential for imaging in vivo and forming high resolution optical tomograms in real time. It opens an opportunity for the development of a...
Li, Youzhi; Zhang, Huiliang; Kim, Chulhong; Wagner, Kelvin H.; Hemmer, Philip; Wang, Lihong V.
Three-dimensional imaging of xenograft tumors using optical computed and emission tomography
The physical basis and preliminary applications of optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) are introduced, as new techniques with potential to provide unique 3D information on a variety of aspects of tumor structure and function. A particular focus here is imaging tumor micro-vasculature, and the spatial distribution of viable tumor cells, although the techniques have the potential for much wider application. The principle attractiveness...
Algorithms for bioluminescence tomography incorporating anatomical information and reconstruction of tissue optical properties
Reconstruction algorithms are presented for a two-step solution of the bioluminescence tomography (BLT) problem. In the first step, a priori anatomical information provided by x-ray computed tomography or by other methods is used to solve the continuous wave (cw) diffuse optical tomography (DOT) problem. A Taylor series expansion approximates the light fluence rate dependence on the optical properties of each region where first and second order direct derivatives of the light fluence rate wit...
Naser, Mohamed A.; Patterson, Michael S.
Optical coherence tomography findings and retinal changes after vitrectomy for optic disc pit maculopathy
Purpose: To study the optical coherence tomography (OCT) patterns in optic disc pit maculopathy and retinal changes after vitreous surgery. Materials and Methods: Retrospective review of consecutive cases with optic disc pit maculopathy seen at two tertiary eye institutes from January 2005 to June 2009. Results: Twenty-four eyes of 23 patients are included. The presenting visual acuity ranged from 20/400 to 20/20 (median:20/80). The median age at presentation was 24 years (range, 6-57 years). Optical coherence tomography demonstrated a combination of retinoschisis and outer layer detachment (OLD) in 19 (79.17%) eyes, OLD only in 3 (12.5%) eyes and retinoschisis only in 2 (8.33%) eyes. An obvious communication (outer layer hole) between the schisis and OLD was seen in 14 (73.68%) of the 19 eyes with both features. Of the 21 eyes with retinoschisis, schisis was present in multiple layers in 15 (71.43%) and single layer in 6 (28.57%) eyes. Eleven eyes underwent pars plana vitrectomy including creation of posterior vitreous detachment (PVD), fluid-air exchange, low intensity laser photocoagulation at the temporal edge of the optic disc pit and non-expansile perfluoropropane gas (14%) injection. Five (45.45%) of 11 eyes undergoing vitrectomy had complete resolution and 4 (36.36%) eyes had partial resolution of maculopathy. Visual acuity improved in 8 (72.72%) of 11 eyes. Conclusion: Optical coherence tomography demonstrates multiple layer schisis and outer layer detachment as main features of optic disc pit maculopathy. Vitrectomy with PVD induction, laser photocoagulation and gas tamponade results in anatomical and visual improvement in most cases with optic disc pit maculopathy.
Sanghi, Gaurav; Padhi, Tapas R; Warkad, Vivekanand U; Vazirani, Jayesh; Gupta, Vishali; Dogra, Mangat R; Gupta, Amod; Das, Taraprasad
Cone beam optical computed tomography-based gel dosimetry
The complex dose distributions delivered by modern, conformal radiation therapy techniques present a considerable challenge in dose verification. Traditional measurement tools are difficult and laborious to use, since complete verification requires that the doses be determined in three dimensions (3D). The difficulty is further complicated by a required target accuracy of +/- 5% for the dose delivery. Gel dosimetry is an attractive option for realizing a tissue-equivalent, 3D dose verification tool with high resolution readout capabilities. However, much important work remains to be completed prior to its acceptance in the clinic. The careful development of easily accessible, fast optical readout tools such as cone beam optical computed tomography (CT) in combination with stable and reliable low-toxicity gel dosimeters is one key step in this process. In this thesis, the performance capabilities and limitations of the two main classes of cone beam optical CT-based absorbing and scattering gel dosimetry are characterized, and their measurement improved through careful matching of dosimeter and scanner performance. These systems are then applied to the evaluation of clinically relevant complex dose distributions. Three-dimensional quality assurance assessments of complex treatment plan dose distributions are shown to be feasible using an optically absorbing Fricke-xylenol-orange-gelatin-based gel dosimeter. Better than 95% voxel agreement is achieved between the plan and the delivery, using 3% dose difference and 3 mm spatial distance-to-agreement gamma function comparison criteria. Small field dose delivery evaluations are demonstrated to be viable using an optically scattering N-isopropylacrylamide (NIPAM)-based polymer gel, with the same comparison criteria. Full treatment process quality assurance is also possible using a NIPAM dosimeter in-phantom, but is limited in its accuracy due to the inherent difficulty of managing the effects of stray light pertubation in the optical attenuation-to-dose calibration.
Olding, Timothy Russell
Spectral Optical Coherent Tomography of Optic Nerve in Diagnosis of Primary Open-angle Glaucoma
Full Text Available The aim of the work is to study the assessment opportunities of the optic nerve morphometric parameters in patients with primary open-angle glaucoma of various stages using spectral optical coherent tomography (OCT.Materials and Methods. 82 patients with various stages of primary open-angle glaucoma have been examined. Objective parameters registration of the optic nerve has been performed by the means of the optic coherent tomograph Cirrus HD-OCT, Carl Zeiss (Germany.Results. There was determined statistically significant reduction of the dimension and the area of neuroretinal zonule as the glaucoma process progressed.Conclusion. The use of spectral OCT in the follow-up of patients with glaucoma will let a physician optimize glaucoma management, as OCT technique enables to monitor optic disc changes progressing in microscopic scale.
A.P. Shakhalova
Optimisation of post mortem cardiac computed tomography compared to optical coherence tomography and histopathology - Technical note
Introduction: Coronary atherosclerosis is a leading cause of mortality. New technological developments in computed tomography (CT), including dual energy, iterative reconstructions and high definition scanning, could significantly improve the non-invasive identification of atherosclerosis plaques. Here, a new method for optimising cardiac coronary CT with optical coherence tomography (OCT) and histopathology is presented. Materials and methods: Twenty human hearts obtained from autopsies were used. A contrast agent that solidifies after cooling was injected into the coronary arteries. CT scanning was performed on the heart alone as well as with the heart in a chest phantom. We used eight different CT protocols and the newest CT technique to image every heart. The OCT and CT images were compared with their corresponding histological sections. A procedure for ensuring the correct alignment of the images was also developed. Results: We have succeeded in developing a new method for post-mortem coronary CT angiography in which an autopsy heart is placed in a chest phantom to simulate clinical CT. Conclusion: The new method permits comparison of CT with OCT and histopathology. This method can also be used for evaluating coronary artery disease, including characterising plaques, and will eventually allow for the detection of rupture-prone plaques, which we will assess in a future study. Clinical testing is our ultimate goal. © 2013 Elsevier Ltd.
Precht, Helle; Leth, Peter Mygind
Radiographic, microcomputer tomography, and optical coherence tomography investigations of ceramic interfaces
Imagistic investigation of the metal-ceramic crowns and fixed partial prostheses represent a very important issue in nowadays dentistry. At this time, in dental office, it is difficult or even impossible to evaluate a metal ceramic crown or bridge before setting it in the oral cavity. The possibilities of ceramic fractures are due to small fracture lines or material defects inside the esthetic layers. Material and methods: In this study 25 metal ceramic crowns and fixed partial prostheses were investigated by radiographic method (Rx), micro computer tomography (MicroCT) and optical coherence tomography (OCT) working in Time Domain, at 1300 nm. The OCT system contains two interferometers and one scanner. For each incident analysis a stuck made of 100 slices was obtain. These slices were used in order to obtain a 3D model of the ceramic interface. Results: RX and MicroCT are very powerful instruments that provide a good characterization of the dental construct. It is important to observe the reflections due to the metal infrastructure that could affect the evaluation of the metal ceramic crowns and bridges. The OCT investigations could complete the imagistic evaluation of the dental construct by offering important information when it is need it.
Sinescu, Cosmin; Negrutiu, Meda Lavinia; Ionita, Ciprian; Topala, Florin; Petrescu, Emanuela; Rominu, Roxana; Pop, Daniela Maria; Marsavina, Liviu; Negru, Radu; Bradu, Adrian; Rominu, Mihai; Podoleanu, Adrian Gh.
Fluorescence guided diffusion optical tomography based on wavelet transform and singular value decomposition
A novel method for optical breast imaging was presented based on fluorescence guided diffusion optical tomography (DOT). In this paper, the time-domain fluorescence parameters (yield and lifetime) were reconstructed based on discrete wavelet transform at first, then the fluorescence images were used to guide and constrain the diffusion optical tomography reconstruction, and the image segmentation strategy based on wavelet coefficient was applied to improve the image quality in DOT. To validate the proposed method, the numerical simulation was performed to demonstrate its computational efficacy. The results showed the feasibility of this method, and the spatial resolution, quantification and computational efficiency in fluorescence diffusion optical tomography and DOT were enhanced evidently.
Zhang, Limin; Zhang, Wei; Gao, Feng; Li, Jiao; Zhao, Huijuan
Clinical study of bladder diseases using optical coherence tomography
Optical Coherence Tomography (OCT), a new optical bioimaging technique was used to evaluate the state of mucosa in the urinary bladder. The state of mucosa of the bladder was evaluated in patients with prostatic adenoma (11 male patients) during the course of prostatectomy operation via a resection cytoscope. An OCT probe was inserted into the biopsy channel of a cystoscope. The sites to be imaged by OCT were determined visually and, after OCT study, underwent excisional biopsy and subsequent histological examination. Children (9 girls) were examined during diagnostic cystoscopy. Our analysis of diagnostic capabilities of OCT in urology relies on the comparison of OCT information on normal and morphologically altered tissues. OCT is able to provide objective data concerning the structure of mucosa of the bladder due to the difference in optical properties of different layers in tissue. The epithelium and the layers of connective tissue, both in norm and pathology, are clearly visualized in the tomograms. Our OCT study of healthy mucosa of the urinary bladder has demonstrated that the epithelium appears in the tomograms as an upper highly backscattering layer. An underlying optically less transparent layer, much greater in size than the previous one, corresponds to the connective tissue of the mucosa. Inside this layer, elongated poorly backscattering formations with clear contours are seen; they do not alter the longitudinal structure of the submucosal layer. These formations are blood vessels. Optical patterns characteristic of chronic inflammation are obtained. They correspond, as confirmed histologically, to liquid accumulation, cellular infiltration of mucosal layers, hypervascularization, and fibrosis. OCT information on proliferative processes, such as papillomatosis of the urinary bladder and squamous cell carcinoma, is analyzed. It is shown that OCT can reliably reveal edema of the mucous membrane of the bladder and identify the character of appearing elements, such bulla, granule and polyp. OCT can provide information on the structure of tissue by characterizing its thickness and scattering properties.
Zagainova, Elena; Gladkova, Natalia D.; Strelzova, O.; Sumin, A.; Gelikonov, Grigory V.; Feldchtein, Felix I.; Iksanov, Rashid R.
Metrological reliability of optical coherence tomography in biomedical applications
Optical coherence tomography (OCT) has been proving to be an efficient diagnostics technique for imaging in vivo tissues, an optical biopsy with important perspectives as a diagnostic tool for quantitative characterization of tissue structures. Despite its established clinical use, there is no international standard to address the specific requirements for basic safety and essential performance of OCT devices for biomedical imaging. The present work studies the parameters necessary for conformity assessment of optoelectronics equipment used in biomedical applications like Laser, Intense Pulsed Light (IPL), and OCT, targeting to identify the potential requirements to be considered in the case of a future development of a particular standard for OCT equipment. In addition to some of the particular requirements standards for laser and IPL, also applicable for metrological reliability analysis of OCT equipment, specific parameters for OCT's evaluation have been identified, considering its biomedical application. For each parameter identified, its information on the accompanying documents and/or its measurement has been recommended. Among the parameters for which the measurement requirement was recommended, including the uncertainty evaluation, the following are highlighted: optical radiation output, axial and transverse resolution, pulse duration and interval, and beam divergence.
Goloni, C. M.; Tempor�o, G. P.; Monteiro, E. C.
Optical coherence tomography (OCT) has been proving to be an efficient diagnostics technique for imaging in vivo tissues, an optical biopsy with important perspectives as a diagnostic tool for quantitative characterization of tissue structures. Despite its established clinical use, there is no international standard to address the specific requirements for basic safety and essential performance of OCT devices for biomedical imaging. The present work studies the parameters necessary for conformity assessment of optoelectronics equipment used in biomedical applications like Laser, Intense Pulsed Light (IPL), and OCT, targeting to identify the potential requirements to be considered in the case of a future development of a particular standard for OCT equipment. In addition to some of the particular requirements standards for laser and IPL, also applicable for metrological reliability analysis of OCT equipment, specific parameters for OCT's evaluation have been identified, considering its biomedical application. For each parameter identified, its information on the accompanying documents and/or its measurement has been recommended. Among the parameters for which the measurement requirement was recommended, including the uncertainty evaluation, the following are highlighted: optical radiation output, axial and transverse resolution, pulse duration and interval, and beam divergence
A combined reconstruction-classification method for diffuse optical tomography.
We present a combined classification and reconstruction algorithm for diffuse optical tomography (DOT). DOT is a nonlinear ill-posed inverse problem. Therefore, some regularization is needed. We present a mixture of Gaussians prior, which regularizes the DOT reconstruction step. During each iteration, the parameters of a mixture model are estimated. These associate each reconstructed pixel with one of several classes based on the current estimate of the optical parameters. This classification is exploited to form a new prior distribution to regularize the reconstruction step and update the optical parameters. The algorithm can be described as an iteration between an optimization scheme with zeroth-order variable mean and variance Tikhonov regularization and an expectation-maximization scheme for estimation of the model parameters. We describe the algorithm in a general Bayesian framework. Results from simulated test cases and phantom measurements show that the algorithm enhances the contrast of the reconstructed images with good spatial accuracy. The probabilistic classifications of each image contain only a few misclassified pixels. PMID:19820265
Hiltunen, P; Prince, S J D; Arridge, S
A combined reconstruction-classification method for diffuse optical tomography
We present a combined classification and reconstruction algorithm for diffuse optical tomography (DOT). DOT is a nonlinear ill-posed inverse problem. Therefore, some regularization is needed. We present a mixture of Gaussians prior, which regularizes the DOT reconstruction step. During each iteration, the parameters of a mixture model are estimated. These associate each reconstructed pixel with one of several classes based on the current estimate of the optical parameters. This classification is exploited to form a new prior distribution to regularize the reconstruction step and update the optical parameters. The algorithm can be described as an iteration between an optimization scheme with zeroth-order variable mean and variance Tikhonov regularization and an expectation-maximization scheme for estimation of the model parameters. We describe the algorithm in a general Bayesian framework. Results from simulated test cases and phantom measurements show that the algorithm enhances the contrast of the reconstructed images with good spatial accuracy. The probabilistic classifications of each image contain only a few misclassified pixels.
Hiltunen, P [Department of Biomedical Engineering and Computational Science, Helsinki University of Technology, PO Box 3310, FI-02015 TKK (Finland); Prince, S J D; Arridge, S [Department of Computer Science, University College London, Gower Street London, WC1E 6B (United Kingdom)], E-mail: email@example.com, E-mail: email@example.com, E-mail: email@example.com
Functional imaging of small tissue volumes with diffuse optical tomography
Imaging of dynamic changes in blood parameters, functional brain imaging, and tumor imaging are the most advanced application areas of diffuse optical tomography (DOT). When dealing with the image reconstruction problem one is faced with the fact that near-infrared photons, unlike X-rays, are highly scattered when they traverse biological tissue. Image reconstruction schemes are required that model the light propagation inside biological tissue and predict measurements on the tissue surface. By iteratively changing the tissue-parameters until the predictions agree with the real measurements, a spatial distribution of optical properties inside the tissue is found. The optical properties can be related to the tissue oxygenation, inflammation, or to the fluorophore concentration of a biochemical marker. If the model of light propagation is inaccurate, the reconstruction process will lead to an inaccurate result as well. Here, we focus on difficulties that are encountered when DOT is employed for functional imaging of small tissue volumes, for example, in cancer studies involving small animals, or human finger joints for early diagnosis of rheumatoid arthritis. Most of the currently employed image reconstruction methods rely on the diffusion theory that is an approximation to the equation of radiative transfer. But, in the cases of small tissue volumes and tissues that contain low scattering regions diffusion theory has been shown to be of limited applicability Therefore, we employ a light propagation model that is based on the equation of radiative transfer, which promises to overcome the limitations.
Klose, Alexander D.; Hielscher, Andreas H.
Optical diffraction tomography in an inhomogeneous background medium
The filtered back-propagation algorithm (FBP algorithm) is a computationally fast and efficient inversion algorithm for reconstructing the 3D index of refraction distribution of weak scattering samples in free space from scattered field data collected in a set of coherent optical scattering experiments. This algorithm is readily derived using classical Fourier analysis applied to the Born or Rytov weak scattering models appropriate to scatterers embedded in a non-attenuating uniform background. In this paper, the inverse scattering problem for optical diffraction tomography (ODT) is formulated using the so-called distorted wave Born and Rytov approximations and a generalized version of the FBP algorithm is derived that applies to weakly scattering samples that are embedded in realistic, multiple scattering ODT experimental configurations. The new algorithms are based on the generalized linear inverse of the linear transformation relating the scattered field data to the complex index of refraction distribution of the scattering samples and are in the form of a superposition of filtered data, computationally back propagated into the ODT experimental configuration. The paper includes a computer simulation comparing the generalized Born and Rytov based FBP inversion algorithms as well as reconstructions generated using the generalized Born based FBP algorithm of a step index optical fiber from experimental ODT data
Investigation of a fibre-optic Fizeau interferometer configuration and coherent fibre-optic imaging bundles for optical coherence tomography
Currently several medical imaging techniques are in operation in clinical environments that help the doctors to diagnose diseases before proceeding to treatment. This research investigated and implemented configurations for a medical imaging technique called Optical Coherence Tomography (OCT). The Michelson interferometer has been the principal configuration for OCT systems. For endoscopic OCT applications though such a configuration is susceptible to polarisation induced si...
Sarantavgas, Georgios
UCL multichannel time-resolved system for optical tomography
A multichannel time resolved imaging system is being developed at University College London (UCL) suitable for optical tomography of the human breast and neonatal brain. The system utilizes the time correlated single photon counting technique, operating in reverse start-stop mode. The detectors are custom made multi-anode microchannel plate photomultipliers (Hamamatsu R411OU-05MOD). Signal processing is implemented using fast NIM logic, and the system is based upon the ORTEC 9308-D picosecond time analyzer in place of a conventional time to amplitude converter. The system is designed to acquire 32 channels of time-resolved data simultaneously, with sub-100 ps temporal resolution, and at count rates of at least 2 multiplied by 104 photons per second per channel. This paper discusses the theoretical considerations which led to the final design, and describes the detector and electronic hardware on which the system is based.
Wells, Kevin; Hebden, Jeremy C.; Schmidt, Florian E. W.; Delpy, David T.
Quantitative phase microscopy with off-axis optical coherence tomography.
We have developed a modality for quantitative phase imaging within spectral domain optical coherence tomography based on using an off-axis reference beam. By tilting the propagation of the reference beam relative to that of the sample beam, a spatially varying fringe is generated. Upon detection of this fringe using a parallel spectral domain scheme, the fringe can be used to separate the interference component of the signal and obtain the complex sample field. In addition to providing quantitative phase measurements within a depth resolved measurement, this approach also allows elimination of the complex conjugate artifact, a known limitation of spectral interferometry. The principle of the approach is described here along with demonstration of its capabilities using technical samples. PMID:24686658
Rinehart, Matthew T; Jaedicke, Volker; Wax, Adam
This case report describes the optical coherence tomography (OCT) results of Berlin�s edema in a male subject following blunt ocular trauma from a soccer ball. A 27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after 3 months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlin�s edema secondary to blunt ocular trauma because Berlin�s edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye.
Oladiwura, Dilys; Lim, Lik Thai; Ah-kee, Elliott Yann; Scott, James Angus
Optical coherence tomography examination of patients with hyperopic ametropic amblyopia
Full Text Available AIM: To investigate the changes of retina in amblyopic eye by measuring macular retinal thickness in hyperopicametropic amblyopic patients.METHODS: Optical coherence tomography(OCTwas used to measure the macular retinal thickness value in 17 amblyopic patients(20 eyesand 14 healthy controls(20 eyes. The result was processed as retinal thickness value and thickness map by computer. The data were analyzed by SPSS 13.0 software package. RESULTS: The retinal thickness of central sector or region in amblyopic eyes were thicker than those in normal eyes(PPP>0.05. CONCLUSION: The macular retina thickness of the central region is thicker in hyperopic ametropic amblyopic patient. OCT is a noninvasive, noncontact technique that visualizes the retinal structure in vivo, this technique may be used to find the potential initial neural site of the visual deficit in this condition.
Hong-Chao Xu
Algebraic reconstruction techniques for spectral reconstruction in diffuse optical tomography
Reconstruction in diffuse optical tomography (DOT) necessitates solving the diffusion equation, which is nonlinear with respect to the parameters that have to be reconstructed. Currently applied solving methods are based on the linearization of the equation. For spectral three-dimensional reconstruction, the emerging equation system is too large for direct inversion, but the application of iterative methods is feasible. Computational effort and speed of convergence of these iterative methods are crucial since they determine the computation time of the reconstruction. In this paper, the iterative methods algebraic reconstruction technique (ART) and conjugated gradients (CGs) as well as a new modified ART method are investigated for spectral DOT reconstruction. The aim of the modified ART scheme is to speed up the convergence by considering the specific conditions of spectral reconstruction. As a result, it converges much faster to favorable results than conventional ART and CG methods
Pre-seizure state identified by diffuse optical tomography
In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a ``pre-seizure'' state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.
Zhang, Tao; Zhou, Junli; Jiang, Ruixin; Yang, Hao; Carney, Paul R.; Jiang, Huabei
Quantitative comparison of analysis methods for spectroscopic optical coherence tomography.
Spectroscopic optical coherence tomography (sOCT) enables the mapping of chromophore concentrations and image contrast enhancement in tissue. Acquisition of depth resolved spectra by sOCT requires analysis methods with optimal spectral/spatial resolution and spectral recovery. In this article, we quantitatively compare the available methods, i.e. the short time Fourier transform (STFT), wavelet transforms, the Wigner-Ville distribution and the dual window method through simulations in tissue-like media. We conclude that all methods suffer from the trade-off in spectral/spatial resolution, and that the STFT is the optimal method for the specific application of the localized quantification of hemoglobin concentration and oxygen saturation. PMID:24298417
Bosschaart, Nienke; van Leeuwen, Ton G; Aalders, Maurice C G; Faber, Dirk J
Characterization of eosinophilic esophagitis murine models using optical coherence tomography
Pre-clinical studies using murine models are critical for understanding the pathophysiological mechanisms underlying immune-mediated disorders such as Eosinophilic esophagitis (EoE). In this study, an optical coherence tomography (OCT) system capable of providing three-dimensional images with axial and transverse resolutions of 5 �m and 10 �m, respectively, was utilized to obtain esophageal images from a murine model of EoE-like disease ex vivo. Structural changes in the esophagus of wild-type (Tslpr+/+) and mutant (Tslpr?/?) mice with EoE-like disease were quantitatively evaluated and food impaction sites in the esophagus of diseased mice were monitored using OCT. Here, the capability of OCT as a label-free imaging tool devoid of tissue-processing artifacts to effectively characterize murine EoE-like disease models has been demonstrated.
Alex, Aneesh; Noti, Mario; Wojno, Elia D. Tait; Artis, David; Zhou, Chao
Macular optical coherence tomography findings following blunt ocular trauma.
This case report describes the optical coherence tomography (OCT) results of Berlin's edema in a male subject following blunt ocular trauma from a soccer ball. A 27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after 3 months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlin's edema secondary to blunt ocular trauma because Berlin's edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye. PMID:24899795
Oladiwura, Dilys; Lim, Lik Thai; Ah-Kee, Elliott Yann; Scott, James Angus
Detection and analysis of jade material using optical coherence tomography
Jade is a type of rare and expensive stone. The current approaches for jade exploration and processing are blindly and wasteful. Capable of performing high resolution, cross-sectional sensing of the internal structure of materials, Optical Coherence Tomography (OCT) could be used to greatly facilitate these jade procedures. By detecting the signal intensity and analysing the internal texture, OCT system can indicate if the jade exists and what the type it could be. It provides a tool to guide the artist in designing and making the jade artworks. It also can be used for discrimination of the fake antique jade wares, as well as anti-counterfeiters on the jade market. In this paper, we present how a Swept-Source OCT system to detect and analysis the internal features of jades. Algorithms for feature extraction and classification are described and experimental results with various unearthed jades are demonstrated.
Foveal thickness after phacoemulsification as measured by optical coherence tomography
Full Text Available Gerasimos Th Georgopoulos, Dimitrios Papaconstantinou, Maria Niskopoulou, Marilita Moschos, Ilias Georgalas, Chrysanthi KoutsandreaGlaucoma Department, Medical School, Athens University, Athens, GreeceBackground: Despite a significant body of research, no consistency on postoperative foveal thickness as measured by optical coherence tomography (OCT, can be recorded. The purpose of our study was to evaluate the effect of uncomplicated cataract surgery in the thickness of the retina in the foveal area during the early postoperative period.Methods: In a prospective study, 79 eyes were assessed by OCT, on day 1, and weeks 2 and 4 after uncomplicated phacoemulsification with intraocular lens implantation in the Athens University Clinic. The outcome measure was the thickness of the retina in the foveal area.Results: The thickness of the retina preoperatively is significantly smaller (150.4 � 18.8 (p�< 0.05 than the thickness of the retina on day 1 (171.8 � 21 and week 2 (159.7 � 19 and returned to the initial levels on week 4 (152 � 17.1. The estimated correlation coefficients between preoperative and postoperative thickness of the retina were significant (p <�0.05. Conversely, no association was found between postoperative visual acuity and thickness of the retina, neither between the phacoemulsification energy and retinal thickness. Operation time, although inversely related with postoperative visual acuity, was not associated with the thickness of the retina.Conclusions: Following phacoemulsification, an increase in the foveal thickness was detected in the early postoperative period, quantified and followed up by OCT. The foveal thickness returned to the preoperative level, 1 month following surgery in our study. No association was shown between intraoperative parameters and increased postoperative retinal thickness.Keywords: optical coherence tomography, phacoemulsification, retinal thickness
Gerasimos Th Georgopoulos
Optical coherence tomography: Monte Carlo simulation and improvement by optical amplification
An advanced novel Monte Carlo simulation model of the detection process of an optical coherence tomography (OCT) system is presented. For the first time it is shown analytically that the applicability of the incoherent Monte Carlo approach to model the heterodyne detection process of an OCT system is firmly justified. This is obtained by calculating the heterodyne mixing of the reference and sample beams in a plane conjugate to the discontinuity in the sample probed by the system. Using this ...
Tycho, Andreas; Bjarklev, Anders Overgaard; Andersen, Peter E.
Characterization and Analysis of Relative Intensity Noise in Broadband Optical Sources for Optical Coherence Tomography
Relative intensity noise (RIN) is one of the most significant factors limiting the sensitivity of an optical coherence tomography (OCT) system. The existing and prevalent theory being used for estimating RIN for various light sources in OCT is questionable, and cannot be applied uniformly for different types of sources. The origin of noise in various sources differs significantly, owing to the different physical nature of photon generation. In this study, we characterize and compare RIN of se...
Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics
Various layers of the retina are well known to alter the polarization state of light. Such changes in polarization may be a sensitive indicator of tissue structure and function, and as such have gained increased clinical attention. Here we demonstrate a polarization-sensitive optical coherence tomography (PS-OCT) system that incorporates adaptive optics (AO) in the sample arm and a single line scan camera in the detection arm. We quantify the benefit of AO for PS-OCT in terms of signal-to-noi...
Cense, B.; Gao, W. H.; Brown, J. M.; Jones, S. M.; Jonnal, R. S.; Mujat, M.; Park, B. H.; Boer, J. F.; Miller, D. T.
Optical clearing of flowing blood using dextrans with spectral domain optical coherence tomography
Spectral domain optical coherence tomography (SDOCT) images have been used to investigate the mechanism of optical clearing in flowing blood using dextrans. The depth reflectivity profiles from SDOCT indicate that dextrans become increasingly more effective in reducing scattering in flowing blood, except for 5 mgdl?1 of D�500, with increasing molecular weights (MW 70,000 and 500,000) and concentrations (0.6, 2, and 5 mgdl?1). Among the tested dextrans, D�500 at 2 mgdl?1 had the most s...
Optical-thermal model verification by high-speed optical coherence tomography
Optical-thermal models that can accurately predict temperature rise and damage in blood vessels and surrounding tissue may be used to improve the treatment of vascular disorders. Verification of these models has been hampered by the lack of time- and depth-resolved experimental data. In vitro and in vivo studies were performed to visualize laser irradiation of blood in cuvettes or cutaneous (hamster dorsal skin flap) blood vessels. Two optical coherence tomography systems, one operating at 400 a-scans per second and the other at 4-30 frames per second, were used. For the in vitro study, a frequency doubled Nd:YAG laser was used (532 nm, 10 ms pulse duration, 2 mm spot size, 10 J/cm2 radiant exposure). In vivo, an Argon laser was employed (all lines, 0.1-2.0 s pulse duration, 0.1-1.0 mm spot size, 100- 400 mW power. Video microscopy images were compared to predictions of temperature rise and damage using Monte Carlo and finite difference techniques. In general, predicted damage agreed with actual blood, blood vessel, and surrounding tissue coagulation seen in images. However, limitations of current optical-thermal models were identified, such as the inability to model the dynamic changes in blood optical properties and vessel diameters that were seen in the optical coherence tomography images.
Barton, Jennifer K.; Rollins, Andrew M.; Yazdanfar, Siavash; Pfefer, T. Joshua; Westphal, Volker; Izatt, Joseph A.
Determination of optical properties of oxidative bleaching human dental tissue samples using optical coherence tomography
Oxidative bleaching changes of human teeth induced changes in the optical properties of dental tissue. We introduced 1310 nm wavelengths of optical coherence tomography (OCT) attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the correlation coefficient during the teeth oxidative bleaching procedure. And the quantitative parameters of enamel optical thickness and disruption of the entrance signal (DES) were extracted from the OCT images. The attenuation coefficient of the bleached tissue is 6.2 mm-1 which is significant (p enamel is similar with unbleached tissue which may indicate the refractive index of enamel is unchanged. Moreover, disruption of the entrance signal (DES) analysis showed that remarkable difference was appeared at enamel surface. The results indicate that optical properties of oxidative bleaching human dental tissue can be determined by attenuation coefficient using OCT system.
Ni, Y. R.; Guo, Z. Y.; Shu, S. Y.; Zeng, C. C.; Zhong, H. Q.; Chen, B. L.; Liu, Z. M.; Bao, Y.
Optical palpation: optical coherence tomography-based tactile imaging using a compliant sensor.
We present optical palpation, a tactile imaging technique for mapping micrometer- to millimeter-scale mechanical variations in soft tissue. In optical palpation, a stress sensor consisting of translucent, compliant silicone with known stress-strain behavior is placed on the tissue surface and a compressive load is applied. Optical coherence tomography (OCT) is used to measure the local strain in the sensor, from which the local stress at the sample surface is calculated and mapped onto an image. We present results in tissue-mimicking phantoms, demonstrating the detection of a feature embedded 4.7�mm below the sample surface, well beyond the depth range of OCT. We demonstrate the use of optical palpation to delineate the boundary of a region of tumor in freshly excised human breast tissue, validated against histopathology. PMID:24978261
Kennedy, Kelsey M; Es'haghian, Shaghayegh; Chin, Lixin; McLaughlin, Robert A; Sampson, David D; Kennedy, Brendan F
Optical coherence tomography in dermatology: technical and clinical aspects.
Optical coherence tomography (OCT), a fairly new non-invasive optical real-time imaging modality, is an emergent in vivo technique, based on the interference (Michelson interferometry) of infrared radiation and living tissues, that allows high-resolution, 2- or 3-dimensional, cross-sectional visualisation of microstructural morphology of tissues. OCT provides depth-resolved images of tissues with resolution up to a few micrometers and depth up to several millimetres depending on tissue type. The investigations using OCT to assess skin structure in clinical settings started in the past decade and consequently proved that this imaging method is useful in visualizing subsurface structures of normal skin, including the epidermis, dermoepidermal junction, dermis, hair follicles, blood vessels and sweat ducts. An increasing number of papers brought evidence of the utility and the precision of OCT technology, in its different technical variants, in diagnosing and monitoring skin disorders, including malignancies and inflammatory conditions, respectively. The present comprehensive review describes and illustrates technical aspects and clinical applications of OCT methods in dermatology. PMID:21647692
Gambichler, Thilo; Jaedicke, Volker; Terras, Sarah
Monte Carlo modeling of human tooth optical coherence tomography imaging
We present a Monte Carlo model for optical coherence tomography (OCT) imaging of human tooth. The model is implemented by combining the simulation of a Gaussian beam with simulation for photon propagation in a two-layer human tooth model with non-parallel surfaces through a Monte Carlo method. The geometry and the optical parameters of the human tooth model are chosen on the basis of the experimental OCT images. The results show that the simulated OCT images are qualitatively consistent with the experimental ones. Using the model, we demonstrate the following: firstly, two types of photons contribute to the information of morphological features and noise in the OCT image of a human tooth, respectively. Secondly, the critical imaging depth of the tooth model is obtained, and it is found to decrease significantly with increasing mineral loss, simulated as different enamel scattering coefficients. Finally, the best focus position is located below and close to the dental surface by analysis of the effect of focus positions on the OCT signal and critical imaging depth. We anticipate that this modeling will become a powerful and accurate tool for a preliminary numerical study of the OCT technique on diseases of dental hard tissue in human teeth.
Shi, Boya; Meng, Zhuo; Wang, Longzhi; Liu, Tiegen
Retina-simulating phantom for optical coherence tomography.
Optical coherence tomography (OCT) is a rapidly growing imaging modality, particularly in the field of ophthalmology. Accurate early diagnosis of diseases requires consistent and validated imaging performance. In contrast to more well-established medical imaging modalities, no standardized test methods currently exist for OCT quality assurance. We developed a retinal phantom which mimics the thickness and near-infrared optical properties of each anatomical retinal layer as well as the surface topography of the foveal pit. The fabrication process involves layer-by-layer spin coating of nanoparticle-embedded silicone films followed by laser micro-etching to modify the surface topography. The thickness of each layer and dimensions of the foveal pit are measured with high precision. The phantom is embedded into a commercially available, water-filled model eye to simulate ocular dispersion and emmetropic refraction, and for ease of use with clinical OCT systems. The phantom was imaged with research and clinical OCT systems to assess image quality and software accuracy. Our results indicate that this phantom may serve as a useful tool to evaluate and standardize OCT performance. PMID:24042445
Baxi, Jigesh; Calhoun, William; Sepah, Yasir Jamal; Hammer, Daniel X; Ilev, Ilko; Pfefer, T Joshua; Nguyen, Quan Dong; Agrawal, Anant
Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis
Optical coherence tomography (OCT) has been used as part of a ground breaking translational study to shed some light on one of the worlds most prevalent autoimmune diseases; psoriasis. The work successfully integrates the fields of optical imaging, biochemistry and dermatology in conducting a dermal microdialysis (DMD) trial for quantitative histamine assessment amongst a group of psoriasis sufferers. The DMD process involves temporary insertion of microscopic hollow tubes into a layer of skin to measure the levels of histamine and other important biological molecules in psoriasis. For comparison purposes, DMD catheters were implanted into healthy, peri-lesional and lesional skin regions. The catheters' entry and exit points and their precise locations in the epidermal layer of the skin were confirmed using OCT thus obtaining high resolution, wide-field images of the affected skin as well as catheter placement whilst local microdialysis enabled a tissue chemistry profile to be obtained from these three skin regions including histamine, a local immune system activator known to contribute towards itch and inflammation. Together these tools offer a synergistic approach in the clinical assessment of the disease. In addition, OCT delivered a non-invasive and rapid method for analyzing the affected skin architecture.
O'Connell, M.-L.; O'Connor, W.; Ramsay, B.; Guihen, E.; Ho, W. L.; Leahy, M. J.
Sound field reconstruction using acousto-optic tomography.
When sound propagates through a medium, it results in pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the refractive index that characterizes the propagation of light is not constant, but influenced by the acoustic field. This kind of interaction is known as the acousto-optic effect. The formulation of this physical phenomenon into a mathematical problem can be described in terms of the Radon transform, which makes it possible to reconstruct an arbitrary sound field using tomography. The present work derives the fundamental equations governing the acousto-optic effect in air, and demonstrates that it can be measured with a laser Doppler vibrometer in the audible frequency range. The tomographic reconstruction is tested by means of computer simulations and measurements. The main features observed in the simulations are also recognized in the experimental results. The effectiveness of the tomographic reconstruction is further confirmed with representations of the very same sound field measured with a traditional microphone array. PMID:22559354
Torras-Rosell, Antoni; Barrera-Figueroa, Salvador; Jacobsen, Finn
Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging
Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the �self�-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconst...
Kim, E.; Bowsher, J.; Thomas, A. S.; Sakhalkar, H.; Dewhirst, M.; Oldham, M.
Root canal filling evaluation using optical coherence tomography
Endodontic therapy consists in cleaning and shaping the root canal system, removing organic debris and sealing the intra-canal space with permanent filling materials. The purpose of this study was to evaluate various root canal fillings in order to detect material defects, the marginal adaptation at the root canal walls and to assess the quality of the apical sealing. 21 extracted single-root canal human teeth were selected for this study. We instrumented all roots using NiTi rotary instruments. All canals were enlarged with a 6% taper size 30 GT instrument, 0,5 mm from the anatomical apex. The root canals were irrigated with 5% sodium hypochlorite, followed by 17% ethylenediaminetetraacetic acid (EDTA). After the instrumentation was completed, the root canals were obturated using a thermoplasticizable polymer of polyesters. In order to assess the defects inside the filling material and the marginal fit to the root canal walls, the conebeam micro-computed tomography (CB?CT) was used first. After the CB?CT investigation, time domain optical coherence tomography working in en face mode (TDefOCT) was employed to evaluate the previous samples. The TDefOCT system was working at 1300 nm and was doubled by a confocal channel at 970 nm. The results obtained by CB?CT revealed no visible defects inside the root-canal fillings and at the interfaces with the root-canal walls. TDefOCT investigations permit to visualize a more complex stratificated structure at the interface filling material/dental hard tissue and in the apical region.
Negrutiu, Meda L.; Sinescu, Cosmin; Topala, Florin; Nica, Luminita; Ionita, Ciprian; Marcauteanu, Corina; Goguta, Luciana; Bradu, Adrian; Dobre, George; Rominu, Mihai; Podoleanu, Adrian Gh.
Adaptive optics optical coherence tomography for in vivo mouse retinal imaging
Small animal models of retinal diseases are important to vision research, and noninvasive high resolution in vivo rodent retinal imaging is becoming an increasingly important tool used in this field. We present a custom Fourier domain optical coherence tomography (FD-OCT) instrument for high resolution imaging of mouse retina. In order to overcome aberrations in the mouse eye, we incorporated a commercial adaptive optics system into the sample arm of the refractive FD-OCT system. Additionally, a commercially available refraction canceling lens was used to reduce lower order aberrations and specular back-reflection from the cornea. Performance of the adaptive optics (AO) system for correcting residual wavefront aberration in the mice eyes is presented. Results of AO FD-OCT images of mouse retina acquired in vivo with and without AO correction are shown as well.
Jian, Yifan; Zawadzki, Robert J.; Sarunic, Marinko V.
Wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice.
We present wavefront sensorless adaptive optics (WSAO) Fourier domain optical coherence tomography (FD-OCT) for in vivo small animal retinal imaging. WSAO is attractive especially for mouse retinal imaging because it simplifies optical design and eliminates the need for wavefront sensing, which is difficult in the small animal eye. GPU accelerated processing of the OCT data permitted real-time extraction of image quality metrics (intensity) for arbitrarily selected retinal layers to be optimized. Modal control of a commercially available segmented deformable mirror (IrisAO Inc.) provided rapid convergence using a sequential search algorithm. Image quality improvements with WSAO OCT are presented for both pigmented and albino mouse retinal data, acquired in vivo. PMID:24575347
Jian, Yifan; Xu, Jing; Gradowski, Martin A; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V
Compact MEMS-based Adaptive Optics Optical Coherence Tomography for Clinical Use
We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of the limitation on the current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in the previous AO-OCT instruments. In this instrument, we proposed to add an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminated the tedious process of the trial lenses in clinical imaging. Different amount of spectacle aberration compensation was achieved by motorized stages and automated with the AO computer for ease of clinical use. In addition, the compact AO-OCT was optimized to have minimum system aberrations to reduce AO registration errors and improve AO performance.
Chen, D; Olivier, S; Jones, S; Zawadzki, R; Evans, J; Choi, S; Werner, J
Full Text Available Jonathan H Tzu, Harry W Flynn Jr, Audina M Berrocal, William E Smiddy, Timothy G Murray, Yale L FisherDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USAPurpose: The purpose of this retrospective study was to evaluate the characteristic features, including spectral-domain optical coherence tomography (SD-OCT, clinical course, and outcome of treatment if given for patients with optic disc pit maculopathy.Methods: We investigated a consecutive series of patients with a diagnosis of optic pit maculopathy treated between 2001 and 2012 at the Bascom Palmer Eye Institute. Patients were divided into two main groups, ie, patients who were observed without surgery and patients who received surgical intervention. The main outcome measures were presenting and final visual acuity, and changes in SD-OCT imaging were recorded. Other data including age, gender, eye, age of onset, length of follow-up, location of optic pit, and location of fluid by OCT were also recorded.Results: On OCT, 67% (12/18 of the eyes showed schisis-like cavities, 22% (4/18 had only subretinal fluid, and 17% (3/18 had only a schisis-like cavity without subretinal fluid. In the patients managed by observation, visual acuity was ?20/200 in 6/8 eyes initially and 6/8 eyes at last follow-up. Ten of 18 patients received either focal laser, surgery or both. Six of 10 eyes undergoing surgery had initial visual acuity ? 20/200, and 8 of 10 eyes undergoing surgery had a visual acuity of ?20/200 at last follow-up.Conclusion: In this study, many eyes were observed and remained stable during follow-up. In eyes with reduced vision, surgical intervention produced variable outcomes, and persistent intraretinal/subretinal fluid was a common occurrence.Keywords: optic pit maculopathy, spectral-domain optical coherence tomography
Tzu JH
Full Text Available Purpose: To study the optic disc topographic measurements of normal Indian eyes using optical coherence tomography (OCT. Materials and Methods: One hundred and fifty eyes selected randomly from 150 normal Indian subjects of both sex and various age groups underwent optic disc imaging with the OCT using the fast optic disc protocol. Results: Mean � standard deviation of the optic disc topographic measurements were: disc area 2.63 � 0.55 mm 2 , cup area 0.87 � 0.45 mm 2 , neuroretinal rim area 1.78 � 0.55 mm 2 and cup to disc area ratio 0.33 � 0.15. There was no significant difference in the measurements between males and females. There was no significant correlation with respect to age and refractive errors ranging from -5.0 to +3.0 diopters of spherical equivalent. Conclusion: Our study provides a normative database for the various optic disc topographic measurements and its variations with age, sex and refractive error in normal Indian eyes using OCT.
Dacosta Shaun
The potential of optical coherence tomography in meniscal tear characterization
Meniscal tear is one of the most common knee injuries leading to pain and discomfort. Partial and total meniscectomies have been widely used to treat the avascular meniscal injuries in which tears do not heal spontaneously. However, the meniscectomies would cause an alteration of the tibiofemoral contact mechanics resulting in progressive osteoarthritis (OA). To mitigate the progression of OA, maximal preservation of meniscal tissue is recommended. The clinical challenge is deciding which meniscal tears are amenable to repair and which part of damaged tissues should be removed. Current diagnosis techniques such as arthroscopy and magnetic resonance imaging can provide macrostructural information of menisci, but the microstructural changes that occur prior to the observable meniscal tears cannot be identified by these techniques. Serving as a nondestructive optical biopsy, optical coherence tomography (OCT), a newly developed imaging modality, can provide high resolution, cross-sectional images of tissues and has been shown its capabilty in arthroscopic evaulation of articular cartilage. Our research was to demonstrate the potential of using OCT for nondestructive characterization of the histopathology of different types of meniscal tears from clinical cases in dogs, providing a fundamental understanding of the failure mechanism of meniscal tears. First, cross-sectional images of torn canine menisci obtained from the OCT and scanning electronic microscopy (SEM) were be compared. By studying the organization of collegan fibrils in torn menisci from the SEM images, the feasibility of using OCT to characterize the organization of collegan fibrils was elucidated. Moreover, the crack size of meniscal tears was quantatitively measured from the OCT images. Changes in the crack size of the tear may be useful for understanding the failure mechanism of meniscal tears.
Ling, Hang-Yin; Guo, Shuguang; Thieman, Kelley M.; Wise, Brent T.; Pozzi, Antonio; Xie, Huikai; Horodyski, Marybeth
Integral ceramic superstructure evaluation using time domain optical coherence tomography
Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.
Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.
Selected clinical comparisons of spectral domain and time domain optical coherence tomography.
The authors report four cases where spectral domain optical coherence tomography (SD-OCT) imaged pathology not captured by time domain optical coherence tomography (TD-OCT). These cases include one of angioid streaks, two of juxtafoveal telangiectasia, and one of age-related macular degeneration. In each case, the improved images provided by SD-OCT changed either the management of the patient or the counseling of their disease process. PMID:19485303
Luviano, Damien M; Benz, Matthew S; Kim, Rosa Y; Fish, Richard H; Wong, Tien P; Kegley, Eric N; Brown, David M
Evaluation of fingerprint deformation using optical coherence tomography
Biometric identification systems have important applications to privacy and security. The most widely used of these, print identification, is based on imaging patterns present in the fingers, hands and feet that are formed by the ridges, valleys and pores of the skin. Most modern print sensors acquire images of the finger when pressed against a sensor surface. Unfortunately, this pressure may result in deformations, characterized by changes in the sizes and relative distances of the print patterns, and such changes have been shown to negatively affect the performance of fingerprint identification algorithms. Optical coherence tomography (OCT) is a novel imaging technique that is capable of imaging the subsurface of biological tissue. Hence, OCT may be used to obtain images of subdermal skin structures from which one can extract an internal fingerprint. The internal fingerprint is very similar in structure to the commonly used external fingerprint and is of increasing interest in investigations of identify fraud. We proposed and tested metrics based on measurements calculated from external and internal fingerprints to evaluate the amount of deformation of the skin. Such metrics were used to test hypotheses about the differences of deformation between the internal and external images, variations with the type of finger and location inside the fingerprint.
Gutierrez da Costa, Henrique S.; Maxey, Jessica R.; Silva, Luciano; Ellerbee, Audrey K.
Retinal and choroidal intravascular spectral-domain optical coherence tomography
Purpose:�?? To examine retinal and choroidal blood vessels using spectral-domain optical coherence tomography (SD-OCT). Methods:�?? Retrospective case series. Results:�?? Scans through retinal blood vessels in healthy subjects demonstrated vessel wall reflexes and a tri-layer profile of the blood column on longitudinal scans and a figure-of-eight configuration on cross-sectional scans. Intravascular reflectivity decreased with increasingly oblique angles of observation and was absent when blood flow was parallel to the line of sight. The high blood flow in the choroidal vessels in healthy subjects and the low flow in the retinal vessels in patients with ocular ischaemic syndrome and central retinal artery occlusion were both associated with lower reflectivity of the blood and an unstructured intravascular SD-OCT profile. Discussion:�?? This qualitative in vivo study found a characteristically structured SD-OCT profile of the blood column in retinal vessels with normal blood flow. Both structure and total reflectivityfaded when blood flow was lower or higher than normal or at oblique angles to the line of sight. In conclusion, SD-OCT scans of the vessels in the posterior pole of the eye may assist the clinical assessment of gross abnormalities of ocular blood flow, e.g. in carotid artery stenosis.
Willerslev, Anne; Li, Xiao Q
Laryngeal imaging with polarization-sensitive optical coherence tomography
Objectives/Hypothesis: Optical coherence tomography (OCT), an imaging technology that provides crosssectional subsurface tissue structure images using backscattered light, is a promising noninvasive, imaging modality for in-vivo assessment of vocal fold layered microstructure. Polarization-sensitive OCT (PS-OCT) augments conventional OCT by detecting changes in the polarization state of reflected light. This study imaged various benign laryngeal pathologies in patients undergoing direct laryngoscopy under general anesthesia to determine whether PS-OCT would provide useful additional information about vocal fold microstructure and glottic surface pathology. Study Design:Prospective clinical trial. Methods: Eighteen patients who were undergoing microlaryngoscopy under general anesthesia for benign glottic disease were imaged bilaterally with OCT and PS-OCT (N=34 vocal folds). Intraoperative microphotography guided placement of the imaging probe. Normalappearing glottic tissue was also imaged if present. When clinically indicated, biopsy or complete removal of the lesion established histologic confirmation. Results: PS-OCT provided high quality, vertical, cross-sectional images up to 1.2mm deep that complemented microlaryngoscopy, and conventional OCT for vocal fold pathologies. Scar tissue was visualized by PS-OCT, characterized by a birefringence pattern more intense than that of normal glottic tissue. Conclusions: Combining PS-OCT with OCT during human vocal cord imaging provides useful information in characterizing vocal cord lesions, particularly scar tissue.
Burns, James A.; Kim, Ki Hean; Anderson, R. Rox
Diagnosis of oral submucous fibrosis with optical coherence tomography
The epithelium (EP) thickness and the standard deviation (SD) of A-mode scan intensity in the laminar propria (LP) layer are used as effective indicators for the diagnosis of oral submucous fibrosis (OSF) based on the noninvasive clinical scanning of a swept-source optical coherence tomography (OCT) system of ~6 ?m in axial resolution (in tissue) and 103 dB in sensitivity. Compared with the corresponding parameters in healthy oral mucosal mucosa, in OSF mucosa, the EP thickness becomes smaller and the SD of A-mode scan intensity in the LP layer (LP SD) also becomes smaller. The LP SD can also be used for effectively differentiating OSF (small LP SD) from lesion (large LP SD). This application is particularly useful in the case of a lesion without a clear surface feature. Meanwhile, the use of the SD of A-mode scan intensity in the EP layer (EP SD) can further help in differentiating OSF (medium EP SD) from healthy oral mucosal (small EP SD) and lesion (large EP SD) conditions. Compared with the conventional method of maximum mouth opening measurement, the use of the proposed OCT scanning results can be a more effective technique for OSF diagnosis.
Lee, Cheng-Kuang; Tsai, Meng-Tsan; Lee, Hsiang-Chieh; Chen, Hsin-Ming; Chiang, Chun-Pin; Wang, Yih-Ming; Yang, C. C.
Imaging cutaneous T-Cell lymphoma with optical coherence tomography
Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL) using optical coherence tomography (OCT). Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT-scanned for comparison, but not biopsied. The OCT image and the histological image were compared. Results: The OCT images illustrated a thickened and hyperreflective stratum corneum. OCT also demonstrated several elongated hyporeflective structures in the dermis. The largest structure was measured to have a width of 0.13 mm. A good immediate correlation was found between histology and OCT imaging of the sample. Conclusion: The aetiology of the elongated structures is thought to be lymphomatous infiltrates. Similar findings have been described in ocular lymphoma and may therefore be an important characteristic of cutaneous lymphoma. It may further be speculated that the differences in OCT images may reflect the biological behaviour of the infiltrate. This observation therefore suggests that OCT imaging may be a relevant tool for the in vivo investigation of mycosis fungoides and other CTCLs, but in order to verify these observed patterns in OCT imaging, further investigations will be required. Copyright © 2012 S. Karger AG, Basel.
Ring, H.C.; Hansen Stamp, I.M.
Orthogonal dispersive spectral-domain optical coherence tomography.
Ultrahigh depth range spectral domain optical coherence tomography (SDOCT) can be realized based on the orthogonal dispersive spectrometer consisted by a high spectral resolution virtually-imaged phased array (VIPA) and a low spectral resolution grating. However, two critical issues result in the challenge of obtaining desirable one-dimensional (1-D) spectra from the recorded two-dimensional (2-D) orthogonal spectra for high-quality OD-SDOCT imaging. One is the wavenumber mapping errors and the other is the periodic intensity modulations. The paper proposes a method for desirable reconstruction of 1-D spectra from the recorded 2-D orthogonal spectra. A sample etalon with identical parameters to the dispersive VIPA is used to determine the free spectrum range (FSR) of the VIPA, and spectral phases from two reflecting mirrors are further applied for broadband wavenumber calibration. The cascading of column spectra are performed from interval of four lines of column spectra, and four records of cascaded 1-D spectra are obtained and then averaged to alleviate the periodic intensity modulations. Broadband 1-D spectra are thus reconstructed with an ultrahigh spectral resolution. To demonstrate the feasibility of the proposed method, three typical samples are imaged by the OD-SDOCT system. PMID:24787889
Bao, Wen; Ding, Zhihua; Li, Peng; Chen, Zhiyan; Shen, Yi; Wang, Chuan
Fibre imaging bundles for full-field optical coherence tomography
An imaging fibre bundle is incorporated into a full-field imaging optical coherence tomography system, with the aim of eliminating the mechanical scanning currently required at the probe tip in endoscopic systems. Each fibre within the imaging bundle addresses a Fizeau interferometer formed between the bundle end and the sample, a configuration which ensures down-lead insensitivity of the probe fibres, preventing variations in sensitivity due to polarization changes in the many thousand constituent fibres. The technique allows acquisition of information across a planar region with single-shot measurement, in the form of a 2D image detected using a digital CCD camera. Depth scanning components are now confined within a processing interferometer external to the completely passive endoscopic probe. The technique has been evaluated in our laboratory for test samples, and images acquired using the bundle-based system are presented. Data are displayed either as en-face scans, parallel to the sample surface, or as slices through the depth of the sample, with a spatial resolution of about 30 �m. The minimum detectable reflectivity at present is estimated to be about 10-3, which is satisfactory for many inorganic samples. Methods of improving the signal-to-noise ratio for imaging of lower reflectivity samples are discussed.
Ford, H. D.; Tatam, R. P.
Adaptive compressed sensing for spectral-domain optical coherence tomography
Spectral-domain optical coherence tomography (SD-OCT) is a non-contact and non-invasive method for measuring the change of biological tissues caused by pathological changes of body. CCD with huge number of pixels is usually used in SD-OCT to increase the detecting depth, thus enhancing the hardness of data transmission and storage. The usage of compressed sensing (CS) in SD-OCT is able to reduce the trouble of large data transfer and storage, thus eliminating the complexity of processing system. The traditional CS uses the same sampling model for SD-OCT images of different tissue, leading to reconstruction images with different quality. We proposed a CS with adaptive sampling model. The new model is based on uniform sampling model, and the interference spectral of SD-OCT is considered to adjust the local sampling ratio. Compared with traditional CS, adaptive CS can modify the sampling model for images of different tissue according to different interference spectral, getting reconstruction images with high quality without changing sampling model.
Wang, Yi; Chen, Xiaodong; Wang, Ting; Li, Hongxiao; Yu, Daoyin
Fast retinal layer identification for optical coherence tomography images
Fast method for identifying the internal limiting membrane (ILM) and retinal pigment epithelium (RPE) from optical coherence tomography images is demonstrated. To avoid unnecessary increment of calculation time, a strong downsampling of the original data set is performed to reduce a number of processed pixels. In ILM segmentation, the obtained data cube is filtered with two different kinds of parameters and two estimates for the position of ILM is determined. A simple smoothness value is determined for both estimates and better estimate is used for future processing. A smaller portion of pixels around estimated ILM are extracted from the down sampled data and filtered again and new estimation for ILM position is determined. That procedure is repeated with smaller portion of pixels around ILM and with different filtering parameters. The principle of RPE segmentation is very much similar with ILM identification. Only the used filtering and processing parameters are changed. Algorithm was tested with eight data sets with good reliability. Over 97% of each scans had smaller segmentation error than 5 pixels. Total required data processing time (ILM and RPE segmentation) for data volume with (600x1500x128) pixels was less than 9 seconds.
Fabritius, Tapio; Makita, Shuichi; Miura, Masahiro; Yasuno, Yoshiaki; Myllyl�, Risto
Intra-retinal layer segmentation in optical coherence tomography images.
Retinal layer thickness, evaluated as a function of spatial position from optical coherence tomography (OCT) images is an important diagnostics marker for many retinal diseases. However, due to factors such as speckle noise, low image contrast, irregularly shaped morphological features such as retinal detachments, macular holes, and drusen, accurate segmentation of individual retinal layers is difficult. To address this issue, a computer method for retinal layer segmentation from OCT images is presented. An efficient two-step kernel-based optimization scheme is employed to first identify the approximate locations of the individual layers, which are then refined to obtain accurate segmentation results for the individual layers. The performance of the algorithm was tested on a set of retinal images acquired in-vivo from healthy and diseased rodent models with a high speed, high resolution OCT system. Experimental results show that the proposed approach provides accurate segmentation for OCT images affected by speckle noise, even in sub-optimal conditions of low image contrast and presence of irregularly shaped structural features in the OCT images. PMID:20052083
Mishra, Akshaya; Wong, Alexander; Bizheva, Kostadinka; Clausi, David A
Full-range spectral domain Doppler optical coherence tomography
Spectral domain optical coherence tomography (SD-OCT) systems achieve higher sensitivities compared to time domain OCT systems. However, one of the main challenges in SD-OCT is the obscuring object structure called "ghost image" or "mirror image" that arises from the Fourier transform of a real function. We have designed and developed a phaseshifting- based full-range SD-OCT system that we refer to as the dual detection full range SD-OCT. The proposed technique simultaneously obtains the quadrature components of a complex spectral interference. Therefore, the technique enables full range imaging without any loss of speed and is intrinsically less sensitive to movements of the subject. In this paper, we demonstrate that the dual detection technique can be applied to Doppler imaging without loss in the velocity dynamic range since the phase information of the acquired spectra is preserved. The dual detection full range SD-OCT provides a superior signal-to-noise ratio over a conventional SD-OCT since the most sensitive region around the zero path delay is usable. This capability improves the image quality of not only the structural image but also the Doppler image.
Meemon, P.; Lee, K. S.; Rolland, J. P.
Imaging of artificial cartilage with optical coherence tomography
Tissue Engineering methods have become more and more relevant for orthopedic applications, especially for cartilage repair with autologous chondrocytes. In order to monitor the healing process and bonding between cartilage and the artificial implant, the boundary zone must be imaged non-invasively, for example with OCT. Optical Coherence Tomography (OCT) is a short coherent light based measuring technique which allows the generation of cross-section images of semi-transparent media with a depth resolution of up to 5 ?m and a measuring depth of 1-2 mm. Especially for the imaging of cartilage OCT offers new diagnostic possibilities, as conventional methods such as ultrasound and x-ray imaging often do not yield satisfactory resolution or contrast. In this paper, an OCT measurement setup for imaging of human cartilage tissue with OCT is demonstrated, allowing a detection of local damaging and lesions. Furthermore, both compressed and uncompressed collagen gel pads were implanted into human cartilage samples. OCT measurements are presented for samples in different stages of growth, focusing on the boundary zones. Comparisons with histologies are shown, demonstrating the ability of OCT to enable a monitoring of the healing progress in tissue engineering based therapy.
Eder, K.; Schmitt, R.; M�ller-Rath, R.
Characterization of PET preforms using spectral domain optical coherence tomography
Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in real time. This paper describes a nondestructive approach and all required signal processing steps to characterize the thin inner layers and also to improve the imaging speed and the signal to noise ratio. The algorithm was developed by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This GPU-accelerated white light interferometry technique nondestructively assesses the samples and has high imaging speed advantage, overcoming the bottlenecks in PET performs quality control.
Hosseiny, Hamid; Ferreira, Manuel Jo�o.; Martins, Teresa; Carmelo Rosa, Carla
Automatic segmentation of anterior segment optical coherence tomography images.
Optical coherence tomography (OCT) images can provide quantitative measurements of the eye's entire anterior segment. A new technique founded on a newly proposed level set-based shape prior segmentation model has been developed for automatic segmentation of the cornea's anterior and posterior boundaries. This technique comprises three major steps: removal of regions containing irrelevant structures and artifacts, estimation of the cornea's location using a thresholding technique, and application of the new level set-based shape prior segmentation model to improve segmentation. The performance of our technique is compared to previously developed methods for analysis of the cornea in 33 OCT images of normal eyes, whereby manual annotations are used as a reference standard. The new technique achieves much improved concordance than previous methods, with a mean Dice's similarity coefficient of > 0.92. This demonstrates the technique's potential to provide accurate and reliable measurements of the anterior segment geometry, which is important for many applications, including the construction of representative numerical simulations of the eye's mechanical behavior. PMID:23640074
Williams, Dominic; Zheng, Yalin; Bao, Fangjun; Elsheikh, Ahmed
OCT y fototoxicidad macular / Optical coherence tomography and macular phototoxicity
Scientific Electronic Library Online (English)
Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Caso cl�nico: Se realiza una exploraci�n ocular y tomograf�a de coherencia �ptica (OCT) en tres pacientes con lesiones fotot�xicas retinianas. Las angiograf�as fluoresce�nicas muestran un defecto ventana. La OCT muestra hiporreflectividad en la porci�n externa de la f�vea y fragmentaci�n de las capa [...] s m�s internas entre la porci�n interna de los fotorreceptores y los segmentos externos. Discusi�n: Las lesiones retinianas tras exposici�n a la luz aparecen precozmente mostrando diferentes patrones en la OCT. La OCT sugiere que la disminuci�n de visi�n asocia una lesi�n de fotorreceptores y epitelio pigmentario retiniano (EPR). La OCT es �til para objetivar la retinopat�a fotot�xica donde los cambios oftalmosc�picos pueden estar ausentes o ser m�nimos. Abstract in english Case report: Ocular examinations and optical coherence tomography (OCT) were performed in three patients with retinal phototoxicity lesions. Fluorescein angiography depicted a window defect. OCT exhibited hyporeflectivity at the outer foveal retina and fragmentation of the inner reflective layers, c [...] orresponding to the junction between the inner and outer photoreceptor segments. Discussion: Retinal damage after light exposure has a rapid onset and shows different patterns in OCT examination. OCT findings suggest that decreased visual acuity may be associated with full-thickness photoreceptors and retinal pigment epithelium (RPE) involvement. OCT is a useful tool for objective assessment of retinal pathology in phototoxicity cases where fundus changes may be minimal or absent.
Rodr�guez-Marco, N.A.; Andonegui-Navarro, J.; Compains-Silva, E.; Rebollo-Aguayo, A.; Aliseda-P�rez-de-Madrid, D.; Aranguren-Laflin, M..
OCT y fototoxicidad macular Optical coherence tomography and macular phototoxicity
Full Text Available Caso cl�nico: Se realiza una exploraci�n ocular y tomograf�a de coherencia �ptica (OCT en tres pacientes con lesiones fotot�xicas retinianas. Las angiograf�as fluoresce�nicas muestran un defecto ventana. La OCT muestra hiporreflectividad en la porci�n externa de la f�vea y fragmentaci�n de las capas m�s internas entre la porci�n interna de los fotorreceptores y los segmentos externos. Discusi�n: Las lesiones retinianas tras exposici�n a la luz aparecen precozmente mostrando diferentes patrones en la OCT. La OCT sugiere que la disminuci�n de visi�n asocia una lesi�n de fotorreceptores y epitelio pigmentario retiniano (EPR. La OCT es �til para objetivar la retinopat�a fotot�xica donde los cambios oftalmosc�picos pueden estar ausentes o ser m�nimos.Case report: Ocular examinations and optical coherence tomography (OCT were performed in three patients with retinal phototoxicity lesions. Fluorescein angiography depicted a window defect. OCT exhibited hyporeflectivity at the outer foveal retina and fragmentation of the inner reflective layers, corresponding to the junction between the inner and outer photoreceptor segments. Discussion: Retinal damage after light exposure has a rapid onset and shows different patterns in OCT examination. OCT findings suggest that decreased visual acuity may be associated with full-thickness photoreceptors and retinal pigment epithelium (RPE involvement. OCT is a useful tool for objective assessment of retinal pathology in phototoxicity cases where fundus changes may be minimal or absent.
N.A. Rodr�guez-Marco
Comparison of optical coherence tomography imaging of cataracts with histopathology
This paper presents a comparison of in vivo optical coherence tomography (OCT) captured cataract images to subsequent histopathological examination of the lenticular opacities. OCT imaging was performed on anesthetized Rhesus monkeys, known as the delayed effects colony (DEC), with documented cataracts. These monkeys were exposed to several types of radiation during the mid and late 1960s. The radiation and age related cataracts in these animals were closely monitored using a unique grading system developed specifically for the DEC. In addition to this system, a modified version of a common cataract grading scheme for use in humans was applied. Of the original 18 monkeys imaged, lenses were collected at necropsy from seven of these animals, processed, and compared to OCT images. Results showed a direct correlation between the vertical OCT images and the cataractous lesions seen on corresponding histopathological sections of the lenses. Based on the images obtained and their corresponding documented comparison to histopathology, OCT showed tremendous potential to aid identification and characterization of cataracts. There can be artifactual problems with the images related to movement and shadows produced by opacities. However, with the advent of increased speed in imaging and multiplanar imaging, these disadvantages may easily be overcome.
DiCarlo, Cheryl D.; Roach, William P.; Gagliano, Donald A.; Boppart, Stephen A.; Hammer, Daniel X.; Cox, Ann B.; Fujimoto, James G.
High-resolution full-field spatial coherence gated optical tomography using monochromatic light source
We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.
Srivastava, Vishal; Nandy, Sreyankar; Singh Mehta, Dalip
Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials
In recent years, there has been an ever-growing interest in exploring different optical materials and components to develop compact and effective optical systems. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a custom developed Gabor-domain optical coherence microscopy system centered at 800 nm with 120 nm full width at half maximum enabling unprecedented 2 ?m resolution both laterally and axially in an 8 mm3 volume, we investigated the internal structure of 50 ?m thick films and layered sheets, which prompted the manufacturing process to adopt a compatibilization technique. Based on a custom swept-source OCT system centered at 1320 nm with expanded imaging field-of-view and latest depth of imaging extended to �5 mm, we performed nondestructive metrology of the layer thickness profiles over the depth of a monolithic layered sheet and diagnosed a film compression issue within the sheet. With the OCT metrology, the manufacturing process has been advanced and the layer thickness profile of a recent layered gradient refractive index sheet shows improved uniformity through depth.
Yao, Jianing; Meemon, Panomsak; Lee, Kye-Sung; Rolland, Jannick P.
�Optical Coherence Tomography� en desgarro del epitelio pigmentario retiniano / �Optical Coherence Tomography� of retinal pigment epithelial tears
Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Casos cl�nicos: Se presentan 3 pacientes con desgarro de epitelio pigmentario retiniano (EPR). En dos de ellos, �ste se produjo de manera espont�nea, estando el tercero en relaci�n con la fotocoagulaci�n de una neovascularizaci�n extrafoveal. Se realizaron angiograf�as (AGF) y estudio con tomografia [...] �ptica de coherencia (OCT) que confirmaron el diagn�stico. Discusi�n: Existen pocos estudios sobre OCT en desgarro del EPR. Las principales caracter�sticas son: interrupci�n de la l�nea hiperreflectante del EPR, hiperreflectividad de la coroides en la zona de ausencia de EPR y doble capa de EPR donde �ste est� replegado. Es frecuente el desprendimiento de EPR y neurosensorial asociado. Abstract in english Case reports: Three cases of pigmentary epithelial tears are described in this study. One of them was related to previous extrafoveal photocoagulation, whereas the other two were idiopathic. Fluorescein angiography (FA) and optical coherence tomography (OCT) were performed to confirm the clinical di [...] agnosis. Discussion: Few studies using OCT to assess pigmentary retinal epithelial (RPE) tears have been published in the world literature. The main findings of our study included hyper-reflectant line breaks, choroidal hyper-reflectance due to the lack of RPE and RPE double layering where it was folded. Images were frequently associated with RPE tears and neurosensorial retinal detachment.
C., Torr�n-Fern�ndez-Blanco; E., Ferrer-Novella; O., Ruiz-Moreno; F.M., Honrubia-L�pez.
�Optical Coherence Tomography� en desgarro del epitelio pigmentario retiniano �Optical Coherence Tomography� of retinal pigment epithelial tears
Full Text Available Casos cl�nicos: Se presentan 3 pacientes con desgarro de epitelio pigmentario retiniano (EPR. En dos de ellos, �ste se produjo de manera espont�nea, estando el tercero en relaci�n con la fotocoagulaci�n de una neovascularizaci�n extrafoveal. Se realizaron angiograf�as (AGF y estudio con tomografia �ptica de coherencia (OCT que confirmaron el diagn�stico. Discusi�n: Existen pocos estudios sobre OCT en desgarro del EPR. Las principales caracter�sticas son: interrupci�n de la l�nea hiperreflectante del EPR, hiperreflectividad de la coroides en la zona de ausencia de EPR y doble capa de EPR donde �ste est� replegado. Es frecuente el desprendimiento de EPR y neurosensorial asociado.Case reports: Three cases of pigmentary epithelial tears are described in this study. One of them was related to previous extrafoveal photocoagulation, whereas the other two were idiopathic. Fluorescein angiography (FA and optical coherence tomography (OCT were performed to confirm the clinical diagnosis. Discussion: Few studies using OCT to assess pigmentary retinal epithelial (RPE tears have been published in the world literature. The main findings of our study included hyper-reflectant line breaks, choroidal hyper-reflectance due to the lack of RPE and RPE double layering where it was folded. Images were frequently associated with RPE tears and neurosensorial retinal detachment.
C. Torr�n-Fern�ndez-Blanco
Quantitative photoacoustic imaging: correcting for heterogeneous light fluence distributions using diffuse optical tomography
The specificity of molecular and functional photoacoustic (PA) images depends on the accuracy of the photoacoustic absorption spectroscopy. The PA signal is proportional to the product of the optical absorption coefficient and local light fluence; quantitative PA measurements of the optical absorption coefficient therefore require an accurate estimation of optical fluence. Light-modeling aided by diffuse optical tomography (DOT) can be used to map the required fluence and to reduce errors in ...
Improved bioluminescence and fluorescence reconstruction algorithms using diffuse optical tomography, normalized data, and optimized selection of the permissible source region
Reconstruction algorithms are presented for two-step solutions of the bioluminescence tomography (BLT) and the fluorescence tomography (FT) problems. In the first step, a continuous wave (cw) diffuse optical tomography (DOT) algorithm is used to reconstruct the tissue optical properties assuming known anatomical information provided by x-ray computed tomography or other methods. Minimization problems are formed based on L1 norm objective functions, where normalized values for the light fluenc...
Common path optical coherence tomography based on fiber bundle imager
Optical coherence tomography (OCT) has emerged as a promising medical imaging modality that can provide non-invasive high-resolution tomographic imaging in real-time. Generating high-resolution OCT images in real-time requires a complicated and costly system design. Therefore, there has been an interest in the development of a common-path (CP) approach to OCT which utilizes a simple interferometer where the sample and reference arms share a common optical path. This configuration allows a much simpler system design, lower associated costs, and the ability to use interchangeable probes as well as the freedom to use any arbitrary probe arm length. In this thesis, novel CP optic probes and image processing methods that could make the CP-OCT a practical system for a high-resolution endoscopic imaging have been developed and investigated. Despite the advantages of CP based OCT configurations, CP-OCT have had limited applications since the reference signal is usually obtained from the Fresnel reflection from the distal end of the optical fiber probe. Thus, when the probe is submerged in an aqueous medium or in contact with a target, the magnitude of the reflected power decreases due to the reduced index difference at the fiber probe reference plane. To solve this problem, gold-plated fiber probes were investigated for in situ imaging of retina and surrounding tissues. The probe operating in an aqueous medium was able to provide OCT images that can differentiate various retinal layers. To obtain 2D images, OCT requires a series of axial scans performed by mechanical spatial translation of the probe or the beam. Most current OCT systems use various miniaturized scanning probes in order to obtain lateral scanning. Alternatively, fiber bundle imagers have recently been suggested. However, the results so far have not been promising due to the inefficient coupling of light into the cores and the non-uniformity of the fiber array. Since CP-OCT obtains the reference at the distal end of the probe, it can overcome the difference between the optical properties between the fiber bundle pixels. In this work, the feasibility of pseudo-scanningless probe has been explored based on fiber bundle imager in the CP-OCT. The mechanical lateral scans are accomplished outside the specimen at the proximal entrance of the fiber bundle. This eliminated the need for moving parts in the distal end of the probe. Finally, to enhance the quality of OCT images obtained using a fiber bundle imager. An image processing method that can remove the fiber bundle's pixelation artifact due to the inherent arrangement of the fiber core arrays is proposed and studied. This method of eliminating pixelization effect from en face OCT image is based on applying a histogram equalization process followed by a weighted-averaged Gaussian smoothing filtering to not only remove the structural artifact of the bundle but also to enhances the image quality with minimum blurring of object's image features.
Han, Jae Ho
Validation of optical coherence tomography in vivo using cryostat histology
We aimed to validate for the first time optical coherence tomography (OCT) measurements of epidermal thickness (ET) using cryopreparation for histology. OCT assessments of ET were performed on healthy skin using the algorithms as follows: first, peak-to-valley analysis of the A-scan (ET-OCT-V), second, line-traced image analysis of the B-scan (ET-OCT-IA). Histology was performed using cryostat sections which were also evaluated using the image analysis (ET-Histo). We selected 114 samples, including B-scans and corresponding histology, for method comparison between ET-OCT-IA and ET-Histo. Forty-two A-scans were available for method comparison between ET-OCT-V and ET-Histo. Bland and Altman plots revealed a marked bias with wide 95% limits of agreement for ET-OCT-V versus ET-Histo. Comparison of ET-OCT-IA versus ET-Histo revealed only a slight bias and narrow 95% limits of agreement. A-scan analysis for ET determination is linked to significant limitations and lacks agreement with histology. By contrast, we observed satisfactory agreement between ET-OCT-IA and ET-Histo indicating that both methods can be utilized interchangeably. OCT using the line-traced image analysis of the B-scan appears to be a valid and relatively practicable method for the determination of ET in vivo. Furthermore, the comparisons with the in vivo OCT profiles demonstrate that cryostat sectioning provides a better preservation of relative and absolute dimensions of skin layers than paraffin embedding. (note)
Performance comparison of different metrics for spectroscopic optical coherence tomography
When light interacts with a scattering medium, the spectrum of the incident light undergoes changes that are dependent on the size of the scatterers in the medium. Spectroscopic Optical Coherence Tomography (S-OCT) is a method that can be used to ascertain the resulting spatially-dependent spectral information. In fact, S-OCT is sensitive to structures that are below the spatial resolution of the system, making S-OCT a promising tool for diagnosing many diseases and biological processes that change tissue structure, like cancer. The most important signal processing steps for S-OCT are the depth-resolved spectral analysis and the calculation of a spectroscopic metric. While the former calculates the spectra from the raw OCT data, the latter analyzes the information content of the processed depth-resolved spectra. We combine the Dual Window spectral analysis with different spectroscopic metrics, which are used as an input to colorize intensity based images. These metrics include the spectral center of mass method, principal component (PCA) and phasor analysis. To compare the performance of the metrics in a quantitative manner, we use a cluster algorithm to calculate efficiencies for all methods. For this purpose we use phantom samples which contain areas of microspheres of different sizes. Our results demonstrate that PCA and phasor analysis have the highest efficiencies, and can clearly separate these areas. Finally we will present data from cartilage tissue under static load in vitro. These preliminary results show that S-OCT can generate additional contrast in biological tissue in comparison to the pure intensity based images.
Jaedicke, Volker; Agcaer, Semih; Robles, Francisco E.; Steinert, Marian; Jones, David; Goebel, Sebastian; Gerhardt, Nils C.; Welp, Hubert; Hofmann, Martin R.
Multiple step algorithms for fluorescence -enhanced diffuse optical tomography
A discussion on recent works on diffusive inverse problems is presented with a special focus n three-dimensional shape-based imaging methods and their application to small animal imaging by fluorescence-enhanced Diffuse Optical Tomography (DOT). Numerical approaches (Finite Element Method) for handling problems modelled by elliptic coupled PDEs is justified by the complexity of the geometry of the system but is known to be time-and memory-consuming. The use of an 'adjoint field technique' considerably speeds up the treatment and allows a full 3D resolution. Nevertheless, because of the ill-posing of the problem, the reconstruction scheme is sensitive to a priori knowledge on the parameters to be reconstructed. Multiple modality imaging techniques (DOT coupled with CT or MRI for example) is becoming of great interest for introducing a priori knowledge of the regions of interest (ROI) and justifies the use of shape-based methods that reduces the dimension of the system, by identifying a finite number of ROI (absorption, scattering and/or, in our case, fluorescent zones), and intrinsically regularizes the reconstruction of the desired parameters. This study led to the proposal of a multiple step, self regularized, reconstruction algorithm of the bio-distribution of molecular fluorescent probes specially designed for tumour targeting. We introduce the a priori knowledge of the ROI via a segmentation of the results performed with a first rough reconstruction of the fluorescent regions. The results are then refined along iterations of the segmentation/reconstruction scheme. Measurements were performed on calibrated objects (phantoms) as well as in vivo (nude mice) with a plane parallel plate tomographer using a CCD camera as a detection scheme. (authors)
Statistical analysis of high density diffuse optical tomography.
High density diffuse optical tomography (HD-DOT) is a noninvasive neuroimaging modality with moderate spatial resolution and localization accuracy. Due to portability and wear-ability advantages, HD-DOT has the potential to be used in populations that are not amenable to functional magnetic resonance imaging (fMRI), such as hospitalized patients and young children. However, whereas the use of event-related stimuli designs, general linear model (GLM) analysis, and imaging statistics are standardized and routine with fMRI, such tools are not yet common practice in HD-DOT. In this paper we adapt and optimize fundamental elements of fMRI analysis for application to HD-DOT. We show the use of event-related protocols and GLM de-convolution analysis in un-mixing multi-stimuli event-related HD-DOT data. Statistical parametric mapping (SPM) in the framework of a general linear model is developed considering the temporal and spatial characteristics of HD-DOT data. The statistical analysis utilizes a random field noise model that incorporates estimates of the local temporal and spatial correlations of the GLM residuals. The multiple-comparison problem is addressed using a cluster analysis based on non-stationary Gaussian random field theory. These analysis tools provide access to a wide range of experimental designs necessary for the study of the complex brain functions. In addition, they provide a foundation for understanding and interpreting HD-DOT results with quantitative estimates for the statistical significance of detected activation foci. PMID:23732886
Hassanpour, Mahlega S; White, Brian R; Eggebrecht, Adam T; Ferradal, Silvina L; Snyder, Abraham Z; Culver, Joseph P
Imaging tissue engineered blood vessel mimics with optical coherence tomography
Optical coherence tomography (OCT) is a technology that enables 2D cross-sectional images of tissue microstructure. This interferometric technique provides resolutions of approximately 10-20 mum with a penetration depth of 1-2 mm in highly scattering tissues. With the use of fiber optics, OCT systems have been developed for intravascular imaging with a demonstrated improvement in both resolution and dynamic range compared to commercial intravascular ultrasound systems. OCT studies of normal, atherosclerotic, and stented arteries indicate the ability of OCT to visualize arterial structures. These results suggest OCT may be a valuable tool for studying luminal structures in tissue engineered constructs. In the present study, new endoscopic OCT systems and analysis techniques were developed to visualize the growth and response of the cellular lining within a tissue engineered blood vessel mimic (BVM). The BVM consists of two primary components. A biocompatible polymeric scaffold is used to form the tubular structure. Human microvessel cells from adipose tissue are sodded on to the inner surface of the scaffold. These constructs are then developed and imaged within a sterile bioreactor. Three specific aims were defined for the present study. First, an OCT longitudinal scanning endoscope was developed. With this endoscope, a study of 16 BVMs was performed comparing images from OCT and corresponding histological sections. The study demonstrated that endoscopic imaging did not visually damage the mimic cellular lining. OCT images showed excellent correlation with corresponding histological sections. Second, a concentric three element endoscope was developed to provide radial cross-sections of the BVM. OCT images using this endoscope monitored lining development on three types of polymeric scaffolds. In the third specific aim, automated algorithms were developed to assess the percent cellular coverage of a stent using volumetric OCT images. The results of the present study suggest that OCT endoscopic systems may be a valuable tool for assessing and optimizing the development of tissue engineered constructs. Conversely, the BVMs modeled the arterial response to deployed stents allowing the development of automated OCT analysis software. These results suggest that blood vessel mimics may be used to advance OCT technology and techniques.
Bonnema, Garret Thomas
Multispectral Cerenkov luminescence tomography for small animal optical imaging.
Quite recently Cerenkov luminescence imaging (CLI) has been introduced as a novel pre-clinical imaging for the in vivo imaging of small animals such as mice. The CLI method is based on the detection of Cerenkov radiation (CR) generated by beta particles as they travel into the animal tissues with an energy such that Cerenkov emission condition is satisfied. This paper describes an image reconstruction method called multi spectral diffuse Cerenkov luminescence tomography (msCLT) in order to obtain 3D images from the detection of CR. The multispectral approach is based on a set of 2D planar images acquired using a number of narrow bandpass filters, and the distinctive information content at each wavelength is used in the 3D image reconstruction process. The proposed msCLT method was tested both in vitro and in vivo using 32P-ATP and all the images were acquired by using the IVIS 200 small animal optical imager (Caliper Life Sciences, Alameda USA). Source depth estimation and spatial resolution measurements were performed using a small capillary source placed between several slices of chicken breast. The theoretical Cerenkov emission spectrum and optical properties of chicken breast were used in the modelling of photon propagation. In vivo imaging was performed by injecting control nude mice with 10 MBq of 32P-ATP and the 3D tracer bio-distribution was reconstructed. Whole body MRI was acquired to provide an anatomical localization of the Cerenkov emission. The spatial resolution obtained from the msCLT reconstructed images of the capillary source showed that the FWHM is about 1.5 mm for a 6 mm depth. Co-registered MRI images showed that the Cerenkov emission regions matches fairly well with anatomical regions, such as the brain, heart and abdomen. Ex vivo imaging of the different organs such as intestine, brain, heart and ribs further confirms these findings. We conclude that in vivo 3D bio-distribution of a pure beta-minus emitting radiopharmaceutical such as 32P-ATP can be obtained using the msCLT reconstruction approach. PMID:21716501
Spinelli, Antonello E; Kuo, Chaincy; Rice, Brad W; Calandrino, Riccardo; Marzola, Pasquina; Sbarbati, Andrea; Boschi, Federico
Linear-in-wavenumber swept laser with an acousto-optic deflector for optical coherence tomography.
We report a novel linear-in-wavenumber (k-linear) swept laser source based on an acousto-optic deflector (AOD). The AOD-based optical filter includes an acousto-optic deflector and a reflection grating. The laser may tune k linearly in wavenumber over time due to its appropriate configuration and is favorable for fast imaging because it avoids data resampling and recalibration, as are required in conventional swept source optical coherence tomography (SS-OCT). We achieved k-linearity with Pearson's r correlation coefficients of 0.99995 without and 0.99997 with optimization. The laser has a tuning range of 50 nm, a 3 dB swept range of 42 nm (FWHM), output power of 2.56 mW, 6 dB sensitivity roll-off depth of 0.941 mm, and central wavelength of 1064 nm at a scanning rate of ?20 kHz. Scanning rate as high as ?400 kHz is also achieved for this laser with the tuning range 49 nm, swept linearity of 0.99990, output power of 2.30 mW, and a 6 dB sensitivity roll-off depth 0.550 mm. SS-OCT imaging with linear-in-wavenumber swept laser is also demonstrated. PMID:24562118
Huo, Tiancheng; Zhang, Jian; Zheng, Jing-gao; Chen, Tianyuan; Wang, Chengming; Zhang, Ning; Liao, Wenchao; Zhang, Xiao; Xue, Ping
Ex vivo imaging of human thyroid pathology using integrated optical coherence tomography and optical coherence microscopy
We evaluate the feasibility of optical coherence tomography (OCT) and optical coherence microscopy (OCM) for imaging of benign and malignant thyroid lesions ex vivo using intrinsic optical contrast. 34 thyroid gland specimens are imaged from 17 patients, covering a spectrum of pathology ranging from normal thyroid to benign disease/neoplasms (multinodular colloid goiter, Hashimoto's thyroiditis, and follicular adenoma) and malignant thyroid tumors (papillary carcinoma and medullary carcinoma). Imaging is performed using an integrated OCT and OCM system, with <4 ?m axial resolution (OCT and OCM), and 14 ?m (OCT) and <2 ?m (OCM) transverse resolution. The system allows seamless switching between low and high magnifications in a way similar to traditional microscopy. Good correspondence is observed between optical images and histological sections. Characteristic features that suggest malignant lesions, such as complex papillary architecture, microfollicules, psammomatous calcifications, or replacement of normal follicular architecture with sheets/nests of tumor cells, can be identified from OCT and OCM images and are clearly differentiable from normal or benign thyroid tissues. With further development of needle-based imaging probes, OCT and OCM could be promising techniques to use for the screening of thyroid nodules and to improve the diagnostic specificity of fine needle aspiration evaluation.
Zhou, Chao; Wang, Yihong; Aguirre, Aaron D.; Tsai, Tsung-Han; Cohen, David W.; Connolly, James L.; Fujimoto, James G.
Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography
Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.
Changes in retinal nerve fiber layer and optic disc algorithms by optical coherence tomography in glaucomatous Arab subjects
Ferial M Zeried, Uchechukwu L Osuagwu Department of Optometry and Vision Sciences College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia Purpose: To assess the difference in retinal nerve fiber layer (RNFL) and optic disc algorithms between glaucomatous and normal Arab subjects using optical coherence tomography (OCT). Methods: RNFL thickness and optic disc parameters were obtained in 65 patients aged 50.1 � 7.7 years. Percentage differences in all p...
Fm, Zeried; Ul, Osuagwu
Whole body small animal examination with a diffuse optical tomography instrument
We developed a fluorescent diffuse optical tomography instrument in our laboratory to study in vivo tumour growth without any stress or damage for the animal. By taking into account optical heterogeneities, the reconstruction algorithm allows whole body small animal examination. Experimental results obtained with this system on phantoms and on mice deep lung tumours examination are presented in this paper
Investigation of pit formation in laser-irradiated multilayer thin films by using optical coherence tomography
We propose a novel application of optical coherence tomography (OCT) to monitor pit formation in laser-irradiated optical storage materials. A multilayer optical storage recordable compact disk is composed of multiple layers, each of different structure. The disks were irradiated with a Q-Switched Nd:YAG laser with an energy of 373 mJ. Post-irradiated disks were evaluated by using OCT, and the images were compared with those obtained by using optical microscopy. Our results indicate that OCT can be a useful instrument for investigating pit formation in multilayer optical storage disks and might also provide information on ways to optimize optical memory technology.
Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning speed and high velocity sensitivity
We have developed a novel phase-resolved optical coherence tomography (OCT) and optical Doppler tomography (ODT) system that uses phase information derived from a Hilbert transformation to image blood flow in human skin with fast scanning speed and high velocity sensitivity. Using the phase change between sequential scans to construct flow-velocity imaging, this technique decouples spatial resolution and velocity sensitivity in flow images and increases imaging speed by more than 2 orders of magnitude without compromising spatial resolution or velocity sensitivity. The minimum flow velocity that can be detected with an axial-line scanning speed of 400 Hz and an average phase change over eight sequential scans is as low as 10 ?m/s , while a spatial resolution of 10 ?m is maintained. Using this technique, we present what are to our knowledge the first phase-resolved OCT/ODT images of blood flow in human skin. (c) 2000 Optical Society of America
High-sensitive full-range optical vibrometry based on Fourier-domain optical coherence tomography
Optical vibrometery based on low coherence Fourier-domain optical coherence tomography (FD-OCT) technique are well capable for providing depth resolved vibration information in comparison with conventional laser based vibrometery. Recently, there has been growing interest in developing coherence-domain vibrometry for various clinical and pre-clinical applications. However, a major drawback of the conventional vibrometer based on Fourier-domain low coherence interferometry is the complex-conjugate ambiguity. This is because in FD-OCT, the detected real valued spectral interferogram is Fourier transformed to localize the scatter within the sample. The Fourier transform of a real valued function is Hermitian, so the reconstructed image is symmetric with respect to the zero-phase delay of the interferometer, leading to ambiguity in interpretation of the resulted OCT images. In this paper, we introduce a full range optical coherence vibrometry to utilize the whole imaging range of the spectrometer. The mirror image elimination is based on the linear phase modulation of the interferometer's reference arm mirror and with an algorithm that exploits Hilbert transform to obtain full range complex imaging.
Subhash, Hrebesh M.; Leahy, Martin
Flexible miniature compound lens design for high-resolution optical coherence tomography balloon imaging catheter
We report on a new optics design for an optical coherence tomography (OCT) balloon imaging catheter. The design involves a miniature compound gradient-index (GRIN) rod lens, which consists of a fiber optic mode-field reducer and relay rod lenses to achieve predictable high lateral resolution at a desired large working distance. The compound lens design significantly simplifies the engineering process for an OCT catheter and enables 3-D full circumferential cross sectional imaging of large lum...
Optical Coherence Tomography Enabling Non Destructive Metrology of Layered Polymeric GRIN Material
Gradient Refractive INdex (GRIN) optical components have historically fallen short of theoretical expectations. A recent breakthrough is the manufacturing of nanolayered spherical GRIN (S-GRIN) polymer optical elements, where the construction method yields refractive index gradients that exceed 0.08. Here we report on the application of optical coherence tomography (OCT), including micron-class axial and lateral resolution advances, as effective, innovative methods for performing nondestructi...
Panomsak Meemon; Jianing Yao; Kye-Sung Lee; Thompson, Kevin P.; Michael Ponting; Eric Baer; Rolland, Jannick P.
Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography
We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the us...
Go?tzinger, Erich; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K.
Non-destructive label-free monitoring of collagen gel remodeling using optical coherence tomography
Matrix remodeling plays a fundamental role in physiological and pathological processes, as well as in tissue engineering applications. In this paper, optical coherence tomography (OCT), a nondestructive optical imaging technology, was used to image collagen gel remodeling by smooth muscle cells (SMCs). The optical scattering properties of collagen-SMC gels were characterized quantitatively by fitting OCT data to a theoretical model. Matrix remodeling over 5 days produced a 10-fold increase in...
Levitz, David; Hinds, Monica T.; Ardeshiri, Ardi; Hanson, Stephen R.; Jacques, Steven L.
Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging
A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 ?m spot size, 5 mm working distance and ...
Sun, Cuiru; Lee, Kenneth K. C.; Vuong, Barry; Cusimano, Michael D.; Brukson, Alexander; Mauro, Antonio; Munce, Nigel; Courtney, Brian K.; Standish, Beau A.; Yang, Victor X. D.
Diffuse optical tomography on finger joints for the diagnosis of rheumatoid arthritis
Rheumatoid arthritis (RA) is characterized by physiological changes, which are caused by inflammatory reactions in the small joints and accompanies changes in the transport of optical radiation. Although such changes can be documented using red to near infrared light in optical diaphanoscopy, their diagnostic evaluation is only of value when compared to an earlier image. The images obtained with optical tomography, using two-dimensional tomograms, should show changes in their spatial distribu...
Excitation spectroscopy in multispectral optical fluorescence tomography: methodology, feasibility, and computer simulation studies
Molecular probes used for in vivo Optical Fluorescence Tomography (OFT) studies in small animals are typically chosen such that their emission spectra lie in the 680�850 nm wavelength range. This is because tissue attenuation in this spectral band is relatively low, allowing optical photons even from deep sites in tissue to reach the animal surface, and consequently be detected by a CCD camera. The wavelength dependence of tissue optical properties within the 680�850 nm band can be exploi...
Chaudhari, Abhijit J.; Ahn, Sangtae; Levenson, Richard; Badawi, Ramsey D.; Cherry, Simon R.; Leahy, Richard M.
Determination of optical scattering properties of highly-scattering media in optical coherence tomography images
We developed a new algorithm that fits optical coherence tomography (OCT) signals as a function of depth to a general theoretical OCT model which takes into account multiple scattering effects. With use of this algorithm, it was possible to extract both the scattering coefficient and anisotropy factor from a particular region of interest in an OCT image. The extraction algorithm was evaluated against measurements from an integrating sphere on a set of tissue phantoms and yielded valid results. Finally, a preliminary ex vivo OCT investigation on human aortic specimen indicated that the algorithm may contribute importantly to differentiation between normal and atherosclerotic arteries. We conclude that this algorithm may facilitate tissue characterization by OCT.
Levitz, D.; Thrane, L.
Patency of small laser iridotomy evaluated using anterior-segment optical coherence tomography
Full Text Available Seigo Nakabayashi, Motofumi Kawai, Toru Yamaguchi, Akitoshi Yoshida Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan Abstract: We report the case of a patient with recurrent acute angle-closure glaucoma who had undergone a previous laser iridotomy. Because the initial iridotomy was small, patency could not be determined by slit-lamp examination. Therefore, anterior-segment optical coherence tomography was used to evaluate the patency. Cross-sectional images showed the presence of a membrane with an anterior bowing configuration at the base of the iridotomy, suggesting that recurrent pupillary block was the causative mechanism. A repeat laser iridotomy was performed, with a resultant decrease in the intraocular pressure and widening of the anterior chamber angle. Anterior-segment optical coherence tomography may be helpful to confirm the status of a laser iridotomy, especially when the iridotomy is small. Keywords: anterior-segment optical coherence tomography, laser iridotomy, acute angle-closure glaucoma
Nakabayashi S
Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing
Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate or BABB. The optimized optical clearing procedure of ethanol fixation followed by methyl salicylate clearing preserved the fluorescence of constitutive RFP in whole xenograft tumour specimens, about 1 cc in dimension, indicating successful extension from cell plating experiments to whole tissue samples. Finally, the feasibility of imaging the 3D distribution of viable tumour cells (as indicated by the RFP emission) is demonstrated by optical-ECT imaging of cleared xenograft tumours using an in-house system
Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate or BABB. The optimized optical clearing procedure of ethanol fixation followed by methyl salicylate clearing preserved the fluorescence of constitutive RFP in whole xenograft tumour specimens, about 1 cc in dimension, indicating successful extension from cell plating experiments to whole tissue samples. Finally, the feasibility of imaging the 3D distribution of viable tumour cells (as indicated by the RFP emission) is demonstrated by optical-ECT imaging of cleared xenograft tumours using an in-house system.
Sakhalkar, H S [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Dewhirst, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oliver, T [Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 (United States); Cao, Y [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oldham, M [Department of Radiation Oncology Physics, and Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 (United States)
Comparison of optical coherence tomography, microcomputed tomography, and histology at a three-dimensionally imaged trabecular bone sample
We investigate optical coherence tomography (OCT) as a method for imaging bone. The OCT images are compared directly to those of the standard methods of bone histology and microcomputed tomography (?CT) on a single, fixed human femoral trabecular bone sample. An advantage of OCT over bone histology is its noninvasive nature. OCT also images the lamellar structure of trabeculae at slightly higher contrast than normal bone histology. While ?CT visualizes the trabecular framework of the whole sample, OCT can image additionally cells with a penetration depth limited approximately to 1 mm. The most significant advantage of OCT, however, is the absence of toxic effects (no ionizing radiation), i.e., continuous images may be made and individual cell tracking may be performed. The penetration depth of OCT, however, limits its use to small animal models and small bone organ cultures.
Kasseck, Christoph; Kratz, Marita; Torcasio, Antonia; Gerhardt, Nils C.; van Lenthe, G. Harry; Gambichler, Thilo; Hoffmann, Klaus; Jones, David B.; Hofmann, Martin R.
Diagnostic ability of barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography
Full Text Available OBJECTIVES: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index, calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. METHODS: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. RESULTS: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy met the inclusion criteria for the study. The mean Barrett's index values (� SD were 64.47% � 6.06% and 49.44% � 10.94%in the groups with and without dysthyroid optic neuropathy, respectively (p60% should be carefully examined and followed for the development of dysthyroid optic neuropathy.
M�rio L. R. Monteiro
Estimating optical absorption, scattering, and Grueneisen distributions with multiple-illumination photoacoustic tomography.
While photoacoustic methods offer significant promise for high-resolution optical contrast imaging, quantification has thus far proved challenging. In this paper, a noniterative reconstruction technique for producing quantitative photoacoustic images of both absorption and scattering perturbations is introduced for the case when the optical properties of the turbid background are known and multiple optical illumination locations are used. Through theoretical developments and computational examples, it is demonstrated that multiple-illumination photoacoustic tomography (MI-PAT) can alleviate ill-posedness due to absorption-scattering nonuniqueness and produce quantitative high-resolution reconstructions of optical absorption, scattering, and Gruneisen parameter distributions. While numerical challenges still exist, we show that the linearized MI-PAT framework that we propose has orders of magnitude improved condition number compared with CW diffuse optical tomography. PMID:21743514
Shao, Peng; Cox, Ben; Zemp, Roger J
Diagnostic ability of Barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography
Objectives: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index), calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. Methods: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. Results: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy) met the inclusion criteria for the study. The mean Barrett's index values (�SD) were 64.47% � 6.06% and 49.44% � 10.94% in the groups with and without dysthyroid optic neuropathy, respectively (p60% should be carefully examined and followed for the development of dysthyroid optic neuropathy. (author)
Combined application of optical methods to increase the information content of optical coherent tomography in diagnostics of neoplastic processes
A combined application of optical methods [optical coherent tomography (OCT), cross-polarisation optical coherent tomography, and fluorescence spectroscopy] is proposed for obtaining information on morphological and biochemical changes occurring in tissues in norm and pathology. It is shown that neoplastic and scar changes in esophagus can be distinguished using a combination of polarisation and standard OCT due to the difference between the depolarising properties of the tissues caused by the structural properties of collagenic fibres in stroma. It is shown that OCT combined with fluorescence spectroscopy with the use of 5-aminolevulinic acid is promising for determining the boundaries of carcinoma of the uterine cervix and vulva. It is found that the tumour boundary detected by optical methods coincides with the morphological boundary and extends beyond colposcopically determined boundary by about 2 mm. (laser biology and medicine)
Current and future potential of retinal optical coherence tomography in multiple sclerosis with and without optic neuritis.
Multiple sclerosis (MS) is a disorder characterized by inflammation and neuroaxonal degeneration. The latter is held responsible for the irreversible disability in patients with MS. The eye is a unique window into the brain. With the advent of optical coherence tomography, accurate quantification of retinal layer thickness has become feasible. Neuroaxonal degeneration affecting the retinal layers is structurally and functionally related to pathology in the visual pathways, which is most severe following MS optic neuritis. This is relevant to recognize because MS optic neuritis may mask the subtle thinning of retinal layers associated with global CNS atrophy, which is also related to more global loss of neurological function. Taken together, optical coherence tomography stands at the brink of becoming a validated imaging biomarker for monitoring neurodegeneration in MS and to provide end points for clinical trials. PMID:24832034
Balk, Lisanne J; Petzold, Axel
Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography
We review the development of phantoms for optical coherence tomography (OCT) designed to replicate the optical, mechanical and structural properties of a range of tissues. Such phantoms are a key requirement for the continued development of OCT techniques and applications. We focus on phantoms based on silicone, fibrin and poly(vinyl alcohol) cryogels (PVA-C), as we believe these materials hold the most promise for durable and accurate replication of tissue properties.
Lamouche, Guy; Kennedy, Brendan F.; Kennedy, Kelsey M.; Bisaillon, Charles-Etienne; Curatolo, Andrea; Campbell, Gord; Pazos, Valerie; Sampson, David D.
Assessing near infrared optical properties of ceramic orthodontic brackets using cross-polarization optical coherence tomography.
Secondary decay (caries) under ceramic orthodontic brackets remains a significant dental problem and near infrared cross-polarization optical coherence tomography (CP-OCT) has the potential to detect underlying demineralization. The purpose of this study was to determine the effect of crystalline structure and chemical composition of ceramic brackets on CP-OCT imaging. Four ceramic brackets types, which were divided into monocrystalline and polycrystalline, were examined using CP-OCT. The results of this study demonstrated that the crystallinity of the ceramic brackets affected the 1310 nm CP-OCT imaging with the greatest attenuation seen in polycrystalline alumina brackets. The alumina polycrystalline bracket materials had significantly higher attenuation and scattering than alumina monocrystalline brackets (p?bracket base morphology and composition affected NIR light attenuation. There was considerable attenuation in bracket bases that contained additive zirconium spheres (?30 �m) and this alteration was significantly greater than the jagged alumina crystallographic alterations found in the other bracket systems (p?brackets; however, further investigation into the optical effects of resin integration in the base portion of the brackets is warranted. PMID:24106170
Isfeld, Darren M; Aparicio, Conrado; Jones, Robert S
Size of the optic nerve in computed tomography
Recently, the measurement of optic nerve diameter from CT images has become of great interest. For measuring the optic nerve diameter, the method of Neuro-Ocular index is advocated by Magadure, 1978. But it is very difficult to support this method, because no relationship exists between the ocular diameter and the optic nerve diameter. In order to measure the optic nerve diameter directly by CT image, we examined several Window Level and Window Width settings and print out tables. Results are as follows, 1) Width 400 and all Level settings, all optic nerves appear thick. 2) Width 100, 75, 50 and Level 0 settings show optic nerves thin. 3) Optic nerve looks thick by Width of 100, 75, 50 and Level of -50 settings. 4) By the Level set of CT value of optic nerve in each case and Width set 75 or 50, optic images show nearly the correct diameter. 5) The midpoint of CT value of optic nerve obtained from print out tables are 8 to -22 and the the average is -10. (author)
Theoretical study of Acousto-optical coherence tomography using random phase jumps on US and light
Acousto-optical coherence tomography (AOCT) is a variant of acousto-optic imaging (also called ultrasonic modulation imaging) that makes it possible to get the z resolution with acoustic and optic continuous wave beams. We describe here theoretically the AOCT effect, and we show that the acousto-optic "tagged photons" remain coherent if they are generated within a specific z region of the sample. We quantify the z selectivity for both the "tagged photon" field and for the Lesaffre et al. [Opt. Express 17, 18211 (2009)] photorefractive signal.
Gross, Michel; Ramaz, Fran�ois; Farahi, Salma; Boccara, A C
Computed tomography of the optic nerve with special reference to the attenuation values
The value of computed tomography (CT) for ophthalmology needs no longer to be emphasized. Everything, however, has its limitations. In this article, the limitations of CT for the diagnosis of the optic nerve diameter were studied in an orbit-optic nerve model. The difference of 15 Hounsfield units between two scans which demonstrated the optic nerve having almost the same diameter, as a result of the partial volume effect, was obtained. This suggested that the attenuation values of the optic nerve are markedly influenced by the partial volume effect, and that they require further investigation for clinical use. (author)
Mapping coherence in measurement via full quantum tomography of a hybrid optical detector
Quantum states and measurements exhibit wave-like --- continuous, or particle-like --- discrete, character. Hybrid discrete-continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications, e.g. entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to complementary observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parametrization to-date in quantum tomography experiments...
Zhang, Lijian; Datta, Animesh; Puentes, Graciana; Lundeen, Jeff S; Jin, Xian-Min; Smith, Brian J; Plenio, Martin B; Walmsley, Ian A
Non-uniqueness in fluorescence-enhanced continuous wave diffuse optical tomography
Fluorescence imaging is an attractive imaging modality for understanding biological mechanisms. Among such techniques, continuous wave fluorescence-enhanced diffuse optical tomography (CW-fDOT) is interesting since it is adapted to CCD cameras which allow non-contact measurements on a large number of detection elements for low cost. Here, by extending the derivations previously applied to continuous wave diffuse optical tomography (CW-DOT), we demonstrate that multiple optical configurations may lead to the same sets of optical measurements. We first explain in a ideal case and then in a 'real-world' example when such situations happen. Therefore, one cannot absolutely quantify the fluorescence amount from CW-fDOT measurements without adding priors
Tumor characterization in small animals using magnetic resonance-guided dynamic contrast enhanced diffuse optical tomography
We present a magnetic resonance (MR)-guided near-infrared dynamic contrast enhanced diffuse optical tomography (DCE-DOT) system for characterization of tumors using an optical contrast agent (ICG) and a MR contrast agent [Gd-diethylenetriaminepentaacetic acid (DTPA)] in a rat model. Both ICG and Gd-DTPA are injected and monitored simultaneously using a combined MRI-DOT system, resulting in accurate co-registration between two imaging modalities. Fisher rats bearing R3230 breast tumor are imag...
Lin, Yuting; Thayer, Dave; Nalcioglu, Orhan; Gulsen, Gultekin
Noninvasive Evaluation of Nuclear Morphometry in Breast Lesions Using Multispectral Diffuse Optical Tomography
Breast cancer is the most prevalent cancer and the main cause of cancer-related death in women worldwide. There are limitations associated with the existing clinical tools for breast cancer detection and alternative modalities for early detection and classification of breast cancer are urgently needed. Here we describe an optical imaging technique, called multispectral diffuse optical tomography (DOT), and demonstrate its ability of non-invasively evaluating nuclear morphometry for differenti...
Hajihashemi, Mohammad Reza; Grobmyer, Stephen R.; Al-quran, Samer Z.; Jiang, Huabei
Hierarchical Bayesian regularization of reconstructions for diffuse optical tomography using multiple priors
Diffuse optical tomography (DOT) is a non-invasive brain imaging technique that uses low-levels of near-infrared light to measure optical absorption changes due to regional blood flow and blood oxygen saturation in the brain. By arranging light sources and detectors in a grid over the surface of the scalp, DOT studies attempt to spatially localize changes in oxy- and deoxy-hemoglobin in the brain that result from evoked brain activity during functional experiments. However, the reconstruction...
Abdelnour, Farras; Genovese, Christopher; Huppert, Theodore
Two cases of X-linked retinoschisis with different spectral domain optical coherence tomography findings
Theodore LengByers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, CA, USAAbstract: Spectral domain optical coherence tomography was used to image the maculae of two brothers who had the diagnosis of X-linked retinoschisis maculopathy. One patient demonstrated a large foveal cyst in one eye and a lamellar macular hole in the fellow eye. The second patient demonstrated small retinal cysts in multiple layers of the retina. Spectral domain optical coherence tomograp...
Leng T
Optical Coherence Tomography Imaging: Novel Insights into the Vascular Response After Coronary Stent Implantation
Optical coherence tomography (OCT) is a high-resolution imaging technique that is increasingly used for intracoronary imaging to characterize coronary atherosclerotic plaques and vascular responses after coronary stent implantation. Introduction of optical frequency-domain imaging (OFDI; second generation OCT) has simplified practical use of this novel imaging modality resulting in a more widespread availability in interventional cardiology. Here we highlight recent insights into the acute an...
Jaguszewski, Milosz; Landmesser, Ulf
Photothermal Optical Coherence Tomography of Epidermal Growth Factor Receptor in Live Cells Using Immunotargeted Gold Nanospheres
Molecular imaging is a powerful tool for investigating disease processes and potential therapies in both in vivo and in vitro systems. However, high resolution molecular imaging has been limited to relatively shallow penetration depths that can be accessed with microscopy. Optical coherence tomography (OCT) is an optical analogue to ultrasound with relatively good penetration depth (1-2 mm) and resolution (?1-10 ?m). We have developed and characterized photothermal OCT as a molecular contr...
Skala, Melissa C.; Crow, Matthew J.; Wax, Adam; Izatt, Joseph A.
High-sensitivity ultrasound-modulated optical tomography with a photorefractive polymer
By detecting ultrasonically tagged diffuse light, ultrasound-modulated optical tomography images optical contrast with ultrasonic resolution deep in turbid media, such as biological tissue. However, small detection etendues and weak tagged light submerged in strong untagged background light limit the signal detection sensitivity. In this letter, we report the use of a large area (~5�5 cm2) photorefractive polymer film that yields more than 10 times detection etendue over previous detection s...
Quantitative reconstruction of absorption and scattering coefficients in ultrasound-modulated optical tomography
The simultaneous and/or quantitative recovery of optical absorption and scattering coefficients in ultrasound modulated optical tomography requires the use of a model-based inversion procedure. In this work we employ a linearised forward model as part of a non-linear image reconstruction process, recovering parameters with an error of less than +/-3% from simulated measurements with 1% Gaussian noise and initial conditions differing by 10% from the actual background.
Powell, Samuel; Leung, Terence S.
Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry
This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an ...
Olding, Timothy; Holmes, Oliver; Dejean, Paul; Mcauley, Kim B.; Nkongchu, Ken; Santyr, Giles; Schreiner, L. John
Retinal blood flow detection in diabetic patients by Doppler Fourier domain optical coherence tomography?
We present human retinal blood flow investigation for diabetic patients using Doppler Fourier domain optical coherence tomography (FD-OCT). The scanning pattern consisted of two concentric circles around the optic nerve head. The blood flow in one patient with diabetes and no retinpathy and another patient with treated proliferative diabetic retinopathy were measured. The patient without retinopathy showed a total blood flow value at the lower level of the normal range. The flow distribution ...
Retinal blood flow measurement by circumpapillary Fourier domain Doppler optical coherence tomography
We present in vivo human total retinal blood flow measurements using Doppler Fourier domain optical coherence tomography (OCT). The scan pattern consisted of two concentric circles around the optic nerve head, transecting all retinal branch arteries and veins. The relative positions of each blood vessel in the two OCT conic cross sections were measured and used to determine the angle between the OCT beam and the vessel. The measured angle and the Doppler shift profile were used to compute blo...
Endoscopic Functional Fourier Domain Common Path Optical Coherence Tomography for Microsurgery
A single-arm interferometer based optical coherence tomography (OCT) system known as common-path OCT (CPOCT) is rapidly progressing towards practical application. Due in part to the simplicity and robustness of its design, Fourier Domain CPOCT (FD-CP-OCT) offers advantages in many endoscopic sensing and imaging applications. FD-CP-OCT uses simple, interchangeable fiber optic probes that are easily integrated into small and delicate surgical tools. The system is capable of providing not only h...
Retinal imaging with a combined adaptive optics/optical coherence tomography and adaptive optics/scanning laser ophthalmoscopy system
We describe results of retinal imaging with a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between the two imaging modalities and the potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Additionally this allows for direct comparison between retinal structures that can be imaged with both modalities (e.g., photoreceptor mosaics or microvasculature maps). This dual imaging modality could provide insight into some retinal properties that could not be accessed by a single imaging system. Additionally, extension of OCT and SLO beyond structural imaging may open new avenues for diagnostics and testing in ophthalmology. In particular, non-invasive vasculature mapping with these modalities holds promise of replacing fluorescein angiography in vascular identification. Several new improvements of our system are described, including results of testing a novel 97-actuator deformable mirror and AO-SLO light intensity modulation.
Zawadzki, Robert J.; Jones, Steven M.; Pilli, Suman; Kim, Dae Yu; Olivier, Scot S.; Werner, John S.
High throughput transmission optical projection tomography using low cost graphics processing unit.
We implement the use of a graphics processing unit (GPU) in order to achieve real time data processing for high-throughput transmission optical projection tomography imaging. By implementing the GPU we have obtained a 300 fold performance enhancement in comparison to a CPU workstation implementation. This enables to obtain on-the-fly reconstructions enabling for high throughput imaging. PMID:20052155
Vinegoni, Claudio; Fexon, Lyuba; Feruglio, Paolo Fumene; Pivovarov, Misha; Figueiredo, Jose-Luiz; Nahrendorf, Matthias; Pozzo, Antonio; Sbarbati, Andrea; Weissleder, Ralph
Optical coherence tomography for diagnosis and guided surgery of basal cell carcinoma (Invited Paper)
Results of a study of 43 patients with basal cell carcinoma were used to analyze possibility to apply optical coherence tomography (OCT) to their diagnosis et guided surgery to the depth of 1,5 mm with a resolution of 15 mcm.
Derpalyuk, Elena N.; Gladkova, Natalia D.; Petrova, Galina A.; Nikulin, Nikolay K.; Cherniavsky, Alexandr A.; Iksanov, Rashid R.; Gelikonov, Gregory V.; Myakov, Alexey V.
Tracking both magnitude and direction of 2D transverse motion with optical coherence tomography
We have developed and demonstrated a 2-D transverse motion tracking method that provides quantitative assessment of both direction and magnitude of motion using optical coherence tomography (OCT). This motion tracking method involves scanning the OCT beam circularly and processing the obtained three-dimensional data with novel algorithms.
Liu, Xuan; Kang, Jin U.
Spectral-domain optical coherence tomography imaging of macula-off rhegmatogenous retinal detachment.
The timing of repair and the utility of spectral-domain optical coherence tomography (SD-OCT) for macula-off retinal detachment remains a controversial issue. Four patients who presented with macula-off retinal detachment underwent repair at various time points after symptom onset. Postoperative SD-OCT of the macula demonstrated correlation with final visual acuity. PMID:24672221
Sridhar, Jayanth; Flynn, Harry W
Polarization sensitive optical coherence tomography of melanin provides tissue inherent contrast based on depolarization
Polarization sensitive optical coherence tomography (PS-OCT) was used to investigate the polarization properties of melanin. Measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization. The results indicate that the depolarizing appearance of pigmented structures like, for instance, the retinal pigment epithelium (RPE) is likely to be caused by the melanin granules contained in these cells.
Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Go?tzinger, Erich; Sattmann, Harald; Litschauer, Marco; Hitzenberger, Christoph K.
Complete Two-dimensional Muellermetric Imaging of Biological Tissue Using Heterodyned Optical Coherence Tomography
A polarization-sensitive optical coherence tomography system based on heterodyning and filtering techniques is built to perform Stokesmetric imaging of different layers of depths in a porcine tendon sample. The complete 4\\times4 backscattering Muellermetric images of one layer are acquired using such a system. The images reveal information indiscernible from a conventional OCT system.
Liu, Xue; Shahriar, M S
Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging
A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of similar to 13 x 13 mm(2). The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the...
A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 � 13 mm2. The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral r...
Zhang, Edward Z.; Povazay, Boris; Laufer, Jan; Alex, Aneesh; Hofer, Bernd; Pedley, Barbara; Glittenberg, Carl; Treeby, Bradley; Cox, Ben; Beard, Paul; Drexler, Wolfgang
Measurement of tissue optical properties with optical coherence tomography: Implication for noninvasive blood glucose concentration monitoring
Approximately 14 million people in the USA and more than 140 million people worldwide suffer from diabetes mellitus. The current glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for analysis. There have been enormous efforts by many scientific groups and companies to quantify glucose concentration noninvasively using different optical techniques. However, these techniques face limitations associated with low sensitivity, accuracy, and insufficient specificity of glucose concentrations over a physiological range. Optical coherence tomography (OCT), a new technology, is being applied for noninvasive imaging in tissues with high resolution. OCT utilizes sensitive detection of photons coherently scattered from tissue. The high resolution of this technique allows for exceptionally accurate measurement of tissue scattering from a specific layer of skin compared with other optical techniques and, therefore, may provide noninvasive and continuous monitoring of blood glucose concentration with high accuracy. In this dissertation work I experimentally and theoretically investigate feasibility of noninvasive, real-time, sensitive, and specific monitoring of blood glucose concentration using an OCT-based biosensor. The studies were performed in scattering media with stable optical properties (aqueous suspensions of polystyrene microspheres and milk), animals (New Zealand white rabbits and Yucatan micropigs), and normal subjects (during oral glucose tolerance tests). The results of these studies demonstrated: (1) capability of the OCT technique to detect changes in scattering coefficient with the accuracy of about 1.5%; (2) a sharp and linear decrease of the OCT signal slope in the dermis with the increase of blood glucose concentration; (3) the change in the OCT signal slope measured during bolus glucose injection experiments (characterized by a sharp increase of blood glucose concentration) is higher than that measured in the glucose clamping experiments (characterized by slow, controlled increase of the blood glucose concentration); and (4) the accuracy of glucose concentration monitoring may substantially be improved if optimal dimensions of the probed skin area are used. The results suggest that high-resolution OCT technique has a potential for noninvasive, accurate, and continuous glucose monitoring with high sensitivity.
Larin, Kirill V.
Photons-based medical imaging - Radiology, X-ray tomography, gamma and positrons tomography, optical imaging; Imagerie medicale a base de photons - Radiologie, tomographie X, tomographie gamma et positons, imagerie optique
Fanet, H.; Dinten, J.M.; Moy, J.P.; Rinkel, J. [CEA Leti, Grenoble (France); Buvat, I. [IMNC - CNRS, Orsay (France); Da Silva, A. [Institut Fresnel, Marseille (France); Douek, P.; Peyrin, F. [INSA Lyon, Lyon Univ. (France); Frija, G. [Hopital Europeen George Pompidou, Paris (France); Trebossen, R. [CEA-Service hospitalier Frederic Joliot, Orsay (France)
Assessment of finger joint inflammation by diffuse optical tomography
Inflammatory processes as they occur during rheumatoid arthritis (RA) lead to changes in the optical properties of joint tissues and fluids. These changes occur early on in the disease process and can potentially be used as diagnostic parameter. In this work we report on in vivo studies involving 12 human subjects, which show the potential of diffuse optical tomographic techniques for the diagnosis of inflammatory processes in proximal interphalangeal (PIP) joints.
Hielscher, Andreas H.; Klose, Alexander D.; Scheel, Alexander K.; Backhaus, Marina; Netz, Uwe J.; Beuthan, Juergen
Optical tomography reconstruction algorithm with the finite element method: An optimal approach with regularization tools
Optical tomography is mathematically treated as a non-linear inverse problem where the optical properties of the probed medium are recovered through the minimization of the errors between the experimental measurements and their predictions with a numerical model at the locations of the detectors. According to the ill-posed behavior of the inverse problem, some regularization tools must be performed and the Tikhonov penalization type is the most commonly used in optical tomography applications. This paper introduces an optimized approach for optical tomography reconstruction with the finite element method. An integral form of the cost function is used to take into account the surfaces of the detectors and make the reconstruction compatible with all finite element formulations, continuous and discontinuous. Through a gradient-based algorithm where the adjoint method is used to compute the gradient of the cost function, an alternative inner product is employed for preconditioning the reconstruction algorithm. Moreover, appropriate re-parameterization of the optical properties is performed. These regularization strategies are compared with the classical Tikhonov penalization one. It is shown that both the re-parameterization and the use of the Sobolev cost function gradient are efficient for solving such an ill-posed inverse problem.
Balima, O.; Favennec, Y.; Rousse, D.
Micromachined array tip for multifocus fiber-based optical coherence tomography
High-resolution optical coherence tomography demands a large detector bandwidth and a high numerical aperture for real-time imaging, which is difficult to achieve over a large imaging depth. To resolve these conflicting requirements we propose a novel multifocus fiber-based optical coherence tomography system with a micromachined array tip. We demonstrate the fabrication of a prototype four-channel tip that maintains a 9-14-�m spot diameter with more than 500 �m of imaging depth. Images of a resolution target and a human tooth were obtained with this tip by use of a four-channel cascaded Michelson fiber-optic interferometer, scanned simultaneously at 8 kHz with geometric power distribution across the four channels.
Yang, Victor X. D.; Munce, Nigel; Pekar, Julius; Gordon, Maggie L.; Lo, Stewart; Marcon, Norman E.; Wilson, Brian C.; Vitkin, I. Alex
A combined time-domain diffuse fluorescence and optical tomography system for breast tumor detection
A combined time-domain diffuse fluorescence and optical tomographic system is proposed based on the multi-channel time-correlated single-photon counting (TCSPC) technique, aiming at enhancing the reliability of breast diffuse optical tomography. The system equipped with two pulsed laser diodes at wavelengths of 780 nm and 830 nm that are specific to the maximal excitation and emission of the FDA-approved ICG dye, and works with a 4-channel TCSPC module to acquire the temporal distributions of the light re-emissions 32 boundary sites of tissues in a tandem serial-to-parallel mode. The performance and efficacy of the system are investigated with phantom experiments for diffuse optical tomography (DOT), as well as fluorescence-guided DOT.
Zhang, Wei; Gao, Feng; Wu, Linhui; Ma, Wenjuan; Lu, Yiming; Zhou, Zhongxing
Spectral hole burning for ultrasound-modulated optical tomography of thick tissue
We apply spectral hole burning (SHB)-aided detection in ultrasound-modulated optical tomography (UOT) to image optical heterogeneities in thick tissue-mimicking phantom samples and chicken breast tissue. The efficiency of SHB is improved by using a Tm3+:YAG crystal of higher doping concentration (2.0-atomic%) and a double-pass pumping configuration, in which the pump beam is transmitted through the crystal twice to burn a deeper spectral hole with the available optical intensity. With the imp...
Xu, Xiao; Kothapalli, Sri-rajasekhar; Liu, Honglin; Wang, Lihong V.
A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 ?m spot size, 5 mm working distance and 4 mm field of view. Feasibility of this probe for structural and Doppler shift imaging was tested on porcine femoral blood vessel imaging.
Optical coherence tomography in multiple sclerosis: a systematic review and meta-analysis
Optical coherence tomography (OCT) is a new method that could aid analysis of neurodegeneration in multiple sclerosis (MS) by capturing thinning of the retinal nerve fibre layer (RNFL). Meta-analyses of data for time domain OCT show RNFL thinning of 20.38 pm (95% CI 17-91-22.86, n=2063, p<0.0001) after optic neuritis in MS, and of 7.08 mu m (5.52-8.65, n=3154, p<0.0001) in MS without optic neuritis. The estimated RNFL thinning in patients with MS is greater than the extent expected in normal ...
Improving Key Rate of Optical Fiber Quantum Key Distribution System Based on Channel Tomography
We investigate the key rate of polarization-coded optical fiber-based quantum key distribution system (QKD) with BB84 protocol by channel tomography. The quantum bit error rate (QBER) of the QKD system under depolarizing channel is obtained by analyzing output density operators, transmission rate of channel, transmission rate of the receiver and dark count of single photon detector. According to the estimated QBER an LDPC chosen adaptively is applied to information reconciliation and the practical final key rate is discussed. Analysis results show that compared with cascade scheme and no channel knowledge the key rate can be improved by the proposed reconciliation scheme with channel tomography.
Zhu, Chang-Hua; Quan, Dong-Xiao; Zhang, Fang; Pei, Chang-Xing
Extension of the Gladstone-Dale equation for flame flow field diagnosis by optical computerized tomography
An extended model of the original Gladstone-Dale (G-D) equation is proposed for optical computerized tomography (OCT) diagnosis of flame flow fields. For the purpose of verifying the newly established model, propane combustion is used as a practical example for experiment, and moire deflection tomography is introduced with the probe wavelength 808 nm. The results indicate that the temperature based on the extended model is more accurate than that based on the original G-D equation. In a word, the extended model can be suitable for all kinds of flame flow fields whatever the components, temperature, and ionization are.
Chen Yunyun; Li Zhenhua; Song Yang; He Anzhi
Sagittal laser optical tomography for imaging of rheumatoid finger joints
We present a novel optical tomographic imaging system that was designed to determine two-dimensional spatial distribution of optical properties in a sagittal plane through finger joints. The system incorporates a single laser diode and a single silicon photodetector into a scanning device that records spatially resolved light intensities as they are transmitted through a finger. These data are input to a model-based iterative image reconstruction (MOBIIR) scheme, which uses the equation of radiative transfer (ERT) as a forward model for light propagation through tissue. We have used this system to obtain tomographic images of six proximal interphalangeal finger joints from two patients with rheumatoid arthritis. The optical images were compared to clinical symptoms and ultrasound images
We present a novel optical tomographic imaging system that was designed to determine two-dimensional spatial distribution of optical properties in a sagittal plane through finger joints. The system incorporates a single laser diode and a single silicon photodetector into a scanning device that records spatially resolved light intensities as they are transmitted through a finger. These data are input to a model-based iterative image reconstruction (MOBIIR) scheme, which uses the equation of radiative transfer (ERT) as a forward model for light propagation through tissue. We have used this system to obtain tomographic images of six proximal interphalangeal finger joints from two patients with rheumatoid arthritis. The optical images were compared to clinical symptoms and ultrasound images.
Hielscher, Andreas H.; Klose, Alexander D.; Scheel, Alexander K.; Moa-Anderson, Bryte; Backhaus, Marina; Netz, Uwe; Beuthan, J�rgen
Tomography is a non-intrusive imaging technique being developed at CRNL as an industrial tool for generating quantitative cross-sectional density maps of objects. Of most interest is tomography's ability to: distinguish features within complex geometries where other NDT techniques fail because of the complexity of the geometry; detect/locate small density changes/defects within objects, e.g. void fraction measurements within thick-walled vessels, shrink cavities in castings, etc.; provide quantitative data that can be used in analyses, e.g. of complex processes, or fracture mechanics; and provide objective quantitative data that can be used for (computer-based) quality assurance decisions, thereby reducing and in some cases eliminating the present subjectivity often encountered in NDT. The CRNL program is reviewed and examples are presented to illustrate the potential and the limitations of the technology
Noise statistics of phase-resolved optical coherence tomography imaging: single-and dual-beam-scan Doppler optical coherence tomography.
Noise statistics of phase-resolved optical coherence tomography (OCT) imaging are complicated and involve noises of OCT, correlation of signals, and speckles. In this paper, the statistical properties of phase shift between two OCT signals that contain additive random noises and speckle noises are presented. Experimental results obtained with a scattering tissue phantom are in good agreement with theoretical predictions. The performances of the dual-beam method and conventional single-beam method are compared. As expected, phase shift noise in the case of the dual-beam-scan method is less than that for the single-beam method when the transversal sampling step is large. PMID:24663800
Makita, Shuichi; Jaillon, Franck; Jahan, Israt; Yasuno, Yoshiaki
Optical detection of indocyanine green encapsulated biocompatible poly (lactic-co-glycolic) acid nanoparticles with photothermal optical coherence tomography
We describe a functional imaging paradigm that uses photothermal optical coherence tomography (PT-OCT) to detect indocyanine green (ICG)-encapsulated biocompatible poly(lactic-co-glycolic) acid (PLGA) nanoparticles embedded in highly scattering tissue phantoms with high resolution and sensitivity. The ICG-loaded PLGA nanoparticles were fabricated using a modified emulsification solvent diffusion method. With a 20 kHz axial scan rate, PT-OCT based on spectral-domain interferometric configurati...
Subhash, Hrebesh M.; Xie, Hui; Smith, Jeffrey W.; Mccarty, Owen J. T.
RA diagnostics applying optical tomography in frequency domain
Our aim is to reconstruct the optical parameters in a slice of a finger joint phantom for further investigations about rheumatoid arthritis (RA). Therefore, we have developed a flexible NIR scanning system in order to collect amplitude and phase delay of photon density waves in frequency-domain. A cylindrical finger joint phantom was embedded in a container of Intralipid solution due to the application of an inverse method for infinite geometry. The joint phantom was investigated by a laser beam obtaining several projections. The average optical parameters of each projection was calculated. Using different reconstruction techniques, e.g. ART and SIRT with a special projection operator, we reconstructed the optical parameters in a slice. The projection operator can be heuristically described by a photon path density function of a homogeneous media with infinite geometry. Applied to an object with an unknown distribution of optical parameters it calculates the expectation value of the investigated object. The potentials and limits of these fast reconstruction methods will be presented.
Klose, Alexander D.; Prapavat, Viravuth; Minet, Olaf; Beuthan, Juergen; Mueller, Gerhard J.
Full range spectral domain optical coherence tomography using a fiber-optic probe as a self-phase shifter.
We present a full range handheld probe type spectral domain optical coherence tomography (SD-OCT) method. Here, the sample arm is composed of a tilted fiber-optic cantilever scanner; thus, the phase shift concurrently occurs while sample scanning. With the phase shift, we could achieve a full range complex-conjugate-free OCT image with no additional phase shifters in the reference arm. To realize this technique, a magnetically actuated probe was adopted. Full range SD-OCT images of a pearl, human fingernail, and human tooth were subsequently obtained using this suggested probe. The scanning range and acquisition speed were 3 mm and 20 frames/s, respectively. PMID:22859100
Min, Eun Jung; Shin, Jun Geun; Lee, Jae Hwi; Yasuno, Yoshiaki; Lee, Byeong Ha
Three-dimensional fluorescence-enhanced optical tomography using a hand-held probe based imaging system
Hand-held based optical imaging systems are a recent development towards diagnostic imaging of breast cancer. To date, all the hand-held based optical imagers are used to perform only surface mapping and target localization, but are not capable of demonstrating tomographic imaging. Herein, a novel hand-held probe based optical imager is developed towards three-dimensional (3-D) optical tomography studies. The unique features of this optical imager, which primarily consists of a hand-held prob...
Ge, Jiajia; Zhu, Banghe; Regalado, Steven; Godavarty, Anuradha
Low-noise broadband light generation from optical fibers for use in high-resolution optical coherence tomography.
Broadband light generation from a single-mode optical fiber was developed for high-resolution optical coherence tomography (OCT). No noise amplification was observed for light broadened by self-phase modulation. The investigation showed that the intensity noise of light broadened by self-phase modulation in a single-mode optical fiber was much lower than that of continuum light from a microstructure fiber (MSF). The spectral width of a femtosecond input laser pulse was successfully broadened by a factor of 11, and a coherence length of 3.7 microm was achieved with this source. The application of light broadened by a single-mode optical fiber and MSF was compared for use in OCT imaging. The results showed that a single-mode fiber with a small core diameter is a useful way to generate low-noise, broadband light for high-resolution OCT imaging. PMID:16134843
Wang, Yimin; Tomov, Ivan; Nelson, J Stuart; Chen, Zhongping; Lim, Hyungsik; Wise, Frank
Extraction of optical scattering parameters and attenuation compensation in optical coherence tomography images of multi-layered tissue structures
A recently developed analytical optical coherence tomography (OCT) model [Thrane et al., J. Opt. Soc. Am. A 17, 484 (2000)] allows the extraction of optical scattering parameters from OCT images, thereby permitting attenuation compensation in those images. By expanding this theoretical model, we have developed a new method for extracting optical scattering parameters from multilayered tissue structures in vivo. To verify this, we used a Monte Carlo (MC) OCT model as a numerical phantom to simulate the OCT signal for het-erogeneous multilayered tissue. Excellent agreement between the extracted values of the optical scattering properties of the different layers and the corresponding input reference values of the MC simulation was obtained, which demonstrates the feasibility of the method for in vivo applications. This is to our knowledge the first time such verification has been obtained, and the results hold promise for expanding the functional imaging capabilities of OCT.
Frosz, Michael Henoch
Laser Tomography Adaptive Optics (LTAO): A performance study
We present an analytical derivation of the on-axis performance of Adaptive Optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual error are given for cases of both continuous and discrete turbulent atmospheric profiles. Assuming Shack-Hartmann wavefront sensing with circular apertures, we demonstrate that the error is formally described by integrals of products of three Bessel functions. We compare the performance of Adaptive Optics correction when using natural, Sodium or Rayleigh laser guide stars. For small diameter class telescopes (~5m), we show that a few number of Rayleigh beacons can provide similar performance to that of a single Sodium laser, for a lower overall cost of the instrument. For bigger apertures, using Rayleigh stars may not be such a suitable alternative because of the too severe cone effect that drastically degrades the quality of the correction.
Tatulli, E
In situ multiphoton optical tomography of hair follicles in mice
We report multiphoton in situ optical sectioning of hair follicles in mice and a preliminary investigation of the pathological hair follicles in a transgenic mouse model. Using this imaging technology, we rapidly obtain detailed three-dimensional (3-D) reconstructions of individual hair follicles. No staining or mechanical sectioning is involved, since multiphoton microscopy coregisters two-photon excited fluorescence (TPF) from cells and second harmonic generation (SHG) signals from the extr...
Lyubovitsky, Julia G.; Krasieva, Tatiana B.; Xu, Xiaoman; Andersen, Bogi; Tromberg, Bruce J.
Depth profiling in alumina ceramic by optical coherence tomography
Quality inspection of multi layer ceramic micro devices is a challenging task for large-scale production. Detection of embedded cavities, metal strips or defects within a sintered multi layer alumina ceramic stack is one of the research areas under investigation in the EU-Multilayer project. Since visible light is highly scattered in the turbid alumina, traditional optical imaging techniques fails and acoustic microscopy requires the structure to be soaked in a liquid for good acoustic coupli...
Su, Rong; Mattsson, Lars
Subsurface tumor progression investigated by noninvasive optical second harmonic tomography
Nonlinear optical imaging with femtosecond (10?15-second) laser technology was used to evaluate the subsurface tumor progression in control, dysplasia, and cancerous 7,12-dimethylbenz[a]anthracene-treated hamster cheek pouch mucosa tissues. Two-dimensional images of hamster cheek pouch mucosa tissues were obtained by scanning the second harmonic signal at various sagittal and axial positions. The spatial mapping of the second harmonic signals showed depth differentiation between normal, dys...
Guo, Yici; Savage, Howard E.; Liu, Feng; Schantz, Stimson P.; Ho, P. P.; Alfano, R. R.
Sensing Plasmon-Resonant Nanorods in Tissue with Optical Coherence Tomography
Gold nanoparticles (GNPs) are of high interest for biomedical imaging and photothermal therapy due to their plasmon-resonant nature. However, their utility is limited by transport and targeting to the disease of interest after administration in the living body. Optical coherence tomography can image the distribution of GNPs on the micro- to meso-scale, leading toward a better understanding of these limiting factors. Plasmon-resonant nanorods provide strong optical absorption at near-infrared wavelengths, and are studied using an optical coherence tomography system based on a broadband laser centered at 800nm. The ability to sense GNPs against a biological tissue background is treated as a sensing problem with parameters including the nanorod volume and aspect ratio, optical detection metrics including extinction, a new backscattering albedo metric based on the ratio of backscattering to extinction, and spectroscopic analysis. A key element of this analysis is determining the native tissue optical response, optical signal noise, and spatial heterogeneity before addition of the GNPs. Experiments are performed in skin-like tissue phantoms where a sensitivity of 30ppm is found. Experiments in excised human mammary tumors reveal additional challenges for imaging in real tissues, and the results of various processing techniques are compared.
Oldenburg, Amy
We report the case of a patient with recurrent acute angle-closure glaucoma who had undergone a previous laser iridotomy. Because the initial iridotomy was small, patency could not be determined by slit-lamp examination. Therefore, anterior-segment optical coherence tomography was used to evaluate the patency. Cross-sectional images showed the presence of a membrane with an anterior bowing configuration at the base of the iridotomy, suggesting that recurrent pupillary block was the causative mechanism. A repeat laser iridotomy was performed, with a resultant decrease in the intraocular pressure and widening of the anterior chamber angle. Anterior-segment optical coherence tomography may be helpful to confirm the status of a laser iridotomy, especially when the iridotomy is small.
Nakabayashi, Seigo; Kawai, Motofumi; Yamaguchi, Toru; Yoshida, Akitoshi
A haemodynamic response function model in spatio-temporal diffuse optical tomography
Diffuse optical tomography (DOT) is a new and effective technique for functional brain imaging. It can detect local changes in both oxygenated and deoxygenated haemoglobin concentrations in tissue based on differential absorption at multiple wavelengths. Traditional methods in spatio-temporal analysis of haemoglobin concentrations in diffuse optical tomography first reconstruct the spatial distribution at different time instants independently, then look at the temporal dynamics on each pixel, without incorporating any temporal information as a prior in the image reconstruction. In this work, we present a temporal haemodynamic response function model described by a basis function expansion, in a joint spatio-temporal DOT reconstruction of haemoglobin concentration changes during simulated brain activation. In this joint framework, we simultaneously employ spatial regularization, spectral information and temporal assumptions. We also present an efficient algorithm for solving the associated large-scale systems. The expected improvements in spatial resolution and contrast-to-noise ratio are illustrated with simulations of human brain activation
Full Text Available Theodore LengByers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, CA, USAAbstract: Spectral domain optical coherence tomography was used to image the maculae of two brothers who had the diagnosis of X-linked retinoschisis maculopathy. One patient demonstrated a large foveal cyst in one eye and a lamellar macular hole in the fellow eye. The second patient demonstrated small retinal cysts in multiple layers of the retina. Spectral domain optical coherence tomography allowed high-resolution imaging and characterization of the features in X-linked retinoschisis in these patients, and it highlighted the variability of the same genetic disease, even in one family.Keywords: SD-OCT, XLRS, retina, imaging, maculopathy
Quantitative analysis of the Stratus optical coherence tomography fast macular thickness map reports
Full Text Available The cross sectional optical coherence tomography images have an important role in evaluating retinal diseases. The reports generated by the Stratus fast macular thickness scan protocol are useful for both clinical and research purposes. The centerpoint thickness is an important outcome measure for many therapeutic trials related to macular disease. The data is susceptible to artifacts such as decentration and boundary line errors and could be potentially erroneous. An understanding of how the data is generated is essential before utilizing the data. This article describes the interpretation of the fast macular thickness map report, assessment of the quality of an optical coherence tomography image and identification of the artifacts that could influence the numeric data.
Domalpally Amitha
High resolution 3D image reconstruction in laminar optical tomography based on compressive sensing
Laminar optical tomography (LOT) combines the advantages of diffuse optical tomography image reconstruction and a microscopy-based setup to allow non-contact imaging at depth up to a few millimeters. However, LOT image reconstruction paradigm is inherently an ill-posed and computationally expensive inverse problem. Herein, we cast the LOT inverse problem in the compressive sensing (CS) framework to exploit the sparsity of the fluorophore yield in the image domain and to address the ill-posedness of the LOT inverse problem. We apply this new approach to thick tissue engineering applications. We demonstrate the enhanced resolution of our method in 3-D numerical simulations of anatomically accurate microvasculature and using real data obtained from phantom experiments. Furthermore, CS is shown to be more robust against the reduction of measurements in comparison to the classic methods for such application. Potential benefits and shortcomings of the CS approach in the context of LOT are discussed.
Yang, Fugang; Ozturk, Mehmet S.; Cong, Wenxiang; Wang, Ge; Intes, Xavier
Currently available methodologies for the processing of intravascular ultrasound and optical coherence tomography images.
Optical coherence tomography and intravascular ultrasound are the most widely used methodologies in clinical practice as they provide high resolution cross-sectional images that allow comprehensive visualization of the lumen and plaque morphology. Several methods have been developed in recent years to process the output of these imaging modalities, which allow fast, reliable and reproducible detection of the luminal borders and characterization of plaque composition. These methods have proven useful in the study of the atherosclerotic process as they have facilitated analysis of a vast amount of data. This review presents currently available intravascular ultrasound and optical coherence tomography processing methodologies for segmenting and characterizing the plaque area, highlighting their advantages and disadvantages, and discusses the future trends in intravascular imaging. PMID:24949801
Athanasiou, Lambros; Sakellarios, Antonis I; Bourantas, Christos V; Tsirka, Georgia; Siogkas, Panagiotis; Exarchos, Themis P; Naka, Katerina K; Michalis, Lampros K; Fotiadis, Dimitrios I
Evaluation of the macular architecture of patients operated on from macula-off rhegmatogenous retinal detachment using optical coherence tomography
With the support of optical coherence tomography, to evaluate the macular condition of the patients operated on from rhegmatogenous retinal detachment, with detached macula, who underwent buckling surgery and pars plana vitrectomy
Retinal tumor imaging and volume quantification in mouse model using spectral-domain optical coherence tomography?
We have successfully imaged the retinal tumor in a mouse model using an ultra-high resolution spectral-domain optical coherence tomography (SD-OCT) designed for small animal retinal imaging. For segmentation of the tumor boundaries and calculation of the tumor volume, we developed a novel segmentation algorithm. The algorithm is based on parametric deformable models (active contours) and is driven by machine learning-based region classification, namely a Conditional Random Field. With this al...
Ruggeri, Marco; Tsechpenakis, Gavriil; Jiao, Shuliang; Jockovich, Maria Elena; Cebulla, Colleen; Hernandez, Eleut; Murray, Timothy G.; Puliafito, Carmen A.
Gabor fusion technique in a Talbot bands optical coherence tomography system
In this paper we show how to advantageously combine two effects to enhance the sensitivity with depth in Fourier domain (FD) optical coherence tomography (OCT): Talbot bands (TB) and Gabor-based fusion (GF) technique. TB operation is achieved by routing the two beams, from the object arm and from the reference arm in the OCT interferometer, along parallel separate paths towards the spectrometer. By adjusting the lateral gap between the two beams in their way towards the spectrometer, the posi...
Ultrasound-modulated optical tomography in reflection-mode with ring-shaped light illumination
We have succeeded in implementing ring-shaped light illumination ultrasound-modulated optical tomography (UOT) in reflection mode. The system used intense acoustic bursts and a charge-coupled device camera-based speckle contrast detection method. In addition, the implementation allows placing the tissue sample below (not within) an acoustic coupling water tank and scanning the tissue without moving the sample. Thus, the UOT system is more clinically applicable than previous transmission-mode ...
Kim, Chulhong; Song, Kwang Hyun; Maslov, Konstantin; Wang, Lihong V.
Comparison of Spectral/Fourier Domain Optical Coherence Tomography Instruments for Assessment of Normal Macular Thickness
Purpose: The purpose of this study was to report normal macular thickness measurements and assess reproducibility of retinal thickness measurements acquired by a time-domain optical coherence tomography (OCT) (Stratus, Carl Zeiss Meditec, Inc., Dublin, CA) and three commercially available spectral/Fourier domain OCT instruments (Cirrus HD-OCT, Carl Zeiss Meditec, Inc.; RTVue-100, Optovue, Inc., Fremont, CA; 3D OCT-1000, Topcon, Inc., Paramus, NJ). Methods: Forty randomly selected eyes of ...
Sull, Alan C.; Vuong, Laurel N.; Price, Lori Lyn; Srinivasan, Vivek J.; Gorczynska, Iwona; Fujimoto, James G.; Schuman, Joel S.; Duker, Jay S.
Nondestructive Monitoring of the Repair of Natural Occlusal Lesions using Cross � Polarization Optical Coherence Tomography
Previous remineralization studies employing cross polarization sensitive optical coherence tomography (CP-OCT), have been limited to the repair of artificial enamel-like lesions. In this study we attempted to remineralize existing occlusal lesions on extracted teeth. Lesions were imaged before and after exposure to an acidic remineralization regimen and the integrated reflectivity and lesion depth was calculated. Automated integration routines worked well for assessing the integrated reflecti...
Kang, Hobin; Darling, Cynthia L.; Fried, Daniel
Unusual optical coherence tomography and fundus autofluorescence findings of eclipse retinopathy
A 63-year-old female patient complained of dimness in the central field of vision in the left eye after viewing an annular partial eclipse without adequate eye protection on 22 July 2009. Fundoscopy showed a wrinkled macular surface. Fundus autofluorescence study revealed well-demarcated hyperautofluorescence at the fovea. Optical coherence tomography demonstrated tiny intraretinal cysts. Fluorescein angiography and indocyanine green angiography were unremarkable. Epimacular membrane develope...
Li, Kun-hsien; Chen, San-ni; Hwang, Jiunn-feng; Lin, Chun-ju
Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography
Optical coherence tomography (OCT) is a nondestructive imaging technique offering high temporal and spatial resolution, which makes it a natural choice for assessing tissue mechanical properties. We have developed methods to mechanically analyze the compliance of the rabbit trachea in vivo using tissue deformations induced by tidal breathing, offering a unique tool to assess the behavior of the airways during their normal function. Four-hundred images were acquired during tidal breathing with...
Robertson, Claire; Lee, Sang-won; Ahn, Yeh-chan; Mahon, Sari; Chen, Zhongping; Brenner, Matthew; George, Steven C.
Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery
Application of speckle variance optical coherence tomography (OCT) to endovascular imaging faces difficulty of extensive motion artifacts inherently associated with arterial pulsations in addition to other physiological movements. In this study, we employed a technique involving a fourth order statistical method, kurtosis, operating on the endovascular OCT intensity images to visualize the vasa vasorum of carotid artery in vivo and identify its flow dynamic in a porcine model. The intensity k...
Cheng, Kyle H. Y.; Sun, Cuiru; Vuong, Barry; Lee, Kenneth K. C.; Mariampillai, Adrian; Marotta, Thomas R.; Spears, Julian; Montanera, Walter J.; Herman, Peter R.; Kiehl, Tim-rasmus; Standish, Beau A.; Yang, Victor X. D.
Noninvasive, in vivo assessment of mouse retinal structure using optical coherence tomography
BACKGROUND: Optical coherence tomography (OCT) is a novel method of retinal in vivo imaging. In this study, we assessed the potential of OCT to yield histology-analogue sections in mouse models of retinal degeneration. METHODOLOGY/PRINCIPAL FINDINGS: We achieved to adapt a commercial 3(rd) generation OCT system to obtain and quantify high-resolution morphological sections of the mouse retina which so far required in vitro histology. OCT and histology were compared in models with developmental...
Fischer, M. D.; Huber, G.; Beck, S. C.; Tanimoto, N.; Muehlfriedel, R.; Fahl, E.; Grimm, C.; Wenzel, A.; Reme?, C. E.; Pavert, S. A.; Wijnholds, J.; Pacal, M.; Bremner, R.; Seeliger, M. W.
Cancer imaging by optical coherence tomography: preclinical progress and clinical potential
The last decade has seen dramatic technological advances in the field of optical coherence tomography (OCT) imaging. These advances have driven commercialization and clinical adoption in ophthalmology, cardiology, and gastrointestinal cancer screening. Recently an array of OCT-based imaging tools developed for preclinical intravital cancer imaging applications have yielded exciting new capabilities to probe and monitor cancer progression and response in vivo. Here, we review these results, fo...
Vakoc, Benjamin J.; Fukumura, Dai; Jain, Rakesh K.; Bouma, Brett E.
Optimization of an angled fiber probe for common-path optical coherence tomography
We studied optimization of common-path optical coherence tomography (CP OCT) sensitivity through angled fiber probe. The magnitude of reference power derived from the tip of the fiber was optimized through careful selection of the polishing angle. We experimentally measured the signal-to-noise ratio at different polishing angles to validate the effectiveness of this technique. We also obtained OCT images with the reference optimized CP OCT with more than 10 dB improvement in SNR..
Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis
Assessment and treatment plan for asymptomatic patients with carotid stenosis are based on angiography at the present time. However, angiography or other imaging modalities are limited with their resolution to detect high-risk plaque features. Intravascular optical coherence tomography (IVOCT) recently emerged as a novel imaging modality with a unique resolution to identify vulnerable plaque characteristics. We report use of IVOCT in two separate asymptomatic patients with carotid stenosis with two different plaque types.
Cilingiroglu, Mehmet, E-mail: email@example.com [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States); Hakeem, Abdul [William Beaumont Hospital, Royal Oak, MI (United States); Feldman, Marc [University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Wholey, Mark [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States)
Non-Scanning Optical Coherence Tomography by an Angular Dispersion Imaging Method
Non-scanning optical coherence tomography based on off-axis interferometry has been developed for real-time depth-resolved imaging. By incorporating an angular-dispersion imaging scheme with a phase-shift detection technique, we show that amplitude of the interferogram corresponding to the reflectance of the sample can be detected directly with a CCD camera. Longitudinal cross-sectional images acquired at the rate of 5 Hz are presented.
Umetsu, Eriko; Akiba, Masahiro; Chan, Kin Pui; Tanno, Naohiro
Quantitative phase reconstruction for orthogonal-scanning differential phase-contrast optical coherence tomography.
We present differential phase-contrast optical-coherence tomography (DPC-OCT) with two transversally separated probing beams to sense phase gradients in various directions by employing a rotatable Wollaston prism. In combination with a two-dimensional mathematical-reconstruction algorithm based on a regularized shape from shading method, accurate quantitative phase maps can be determined from a set of two orthogonal en-face DPC-OCT images, as exemplified on various technical samples. PMID:19412254
Heise, Bettina; Stifter, David
High-resolution optical coherence tomography visualization of LASIK flap displacement
Uneventful myopic laser in situ keratomileusis (LASIK) was performed in both eyes of a 33-year-old woman. Two weeks after LASIK, examination of the left eye revealed flap striae radiating inferonasally from the superior hinge. The flap was relifted and repositioned to remove the irregular astigmatism and reduce the striae. Before the flap was relifted, Fourier-domain optical coherence tomography (FD-OCT) showed the gap at the temporal flap, which had not been detected by biomicroscopy. After ...
Salaroli, Camila Hayde?e Rosas; Li, Yan; Huang, David
Application of optical coherence tomography and high-frequency ultrasound imaging during noninvasive laser vasectomy
A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. Optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) are compared for monitoring laser thermal coagulation of the vas in an acute canine model. Bilateral noninvasive laser coagulation of the vas was performed in six dogs (n=12 vasa) using a Ytterbium fiber laser...
Pathogenesis of the dry eye syndrome observed by optical coherence tomography in vitro
Three dimensional optical coherence tomography (OCT) is introduced as a valuable tool to analyze the pathogenesis of corneal diseases. Here, OCT in combination with a novel in vitro model for the dry eye syndrome enables an improved understanding of the underlying damaging process of the ocular surface. En-face OCT projections indicate a deep structural damage of the epithelium and anterior stroma by osmotic forces.
Kray, Oya; Lenz, Markus; Sp�ler, Felix; Kray, Stefan; Kurz, Heinrich
Full-Field Thickness Distribution of Human Tympanic Membrane Obtained with Optical Coherence Tomography
The full-field thickness distribution, three-dimensional surface model and general morphological data of six human tympanic membranes are presented. Cross-sectional images were taken perpendicular through the membranes using a high-resolution optical coherence tomography setup. Five normal membranes and one membrane containing a pathological site are included in this study. The thickness varies strongly across each membrane, and a great deal of inter-specimen variability can be seen in the me...
Spectral domain optical coherence tomography study of pearl-like lesions in the anterior chamber
Wael Soliman*, Ehab I Wasfi*, Omar M AliDepartment of Ophthalmology, Assiut University Hospital, Assiut University, Assiut, Egypt*These authors contributed equally to this workAim: To study the morphological pattern of pearl-like lesions in the anterior chambers of children before and after management using anterior segment spectral domain optical coherence tomography (SD-OCT).Patients and methods: This was a prospective, observational cross-sectional study of patients presenting with peculia...
Principal-component-analysis-based estimation of blood flow velocities using optical coherence tomography intensity signals
The intensity signal in optical coherence tomography contains information about the translational velocity of scatterers, and can be used to quantify blood flow. We apply principal component analysis to efficiently extract this information. We also study use of nonuniform temporal sampling of the intensity signal to increase the range of quantifiable flow velocities. We demonstrate this technique in simulation, phantom and in vivo blood flow measurements, and highlight its potential to enable...
Automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography
We present a new method to automatically segment the thickness of the choroid in the human eye by polarization sensitive optical coherence tomography (PS-OCT). A swept source PS-OCT instrument operating at a center wavelength of 1040 nm is used. The segmentation method is based entirely on intrinsic, tissue specific polarization contrast mechanisms. In a first step, the anterior boundary of the choroid, the retinal pigment epithelium, is segmented based on depolarization. In a second step, th...
Torzicky, Teresa; Pircher, Michael; Zotter, Stefan; Bonesi, Marco; Goetzinger, Erich; Hitzenberger, Christoph K.
Automatic segmentation of the choroid in enhanced depth imaging optical coherence tomography images
Enhanced Depth Imaging (EDI) optical coherence tomography (OCT) provides high-definition cross-sectional images of the choroid in vivo, and hence is used in many clinical studies. However, the quantification of the choroid depends on the manual labelings of two boundaries, Bruch�s membrane and the choroidal-scleral interface. This labeling process is tedious and subjective of inter-observer differences, hence, automatic segmentation of the choroid layer is highly desirable. In this paper, w...
Tian, Jing; Marziliano, Pina; Baskaran, Mani; Tun, Tin Aung; Aung, Tin
Ultra-high resolution optical coherence tomography for encapsulation quality inspection
We present the application of ultra-high resolution optical coherence tomography (UHR-OCT) in evaluation of thin, protective films used in printed electronics. Two types of sample were investigated: microscopy glass and organic field effect transistor (OFET) structure. Samples were coated with thin (1-3 mu m) layer of parylene C polymer. Measurements were done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, photonic crystal fibre and modified,...
Czajkowski, J.; Fabritius, T.; Ulanski, J.; Marszalek, T.; Gazicki-lipman, M.; Nosal, A.; Sliz, R.; Alarousu, E.; Prykari, T.; Myllyla, R.; Jabbour, G.
High-Definition Optical Coherence Tomography for the in vivo Detection of Demodex Mites
Background: Demodex mites are involved in different skin diseases and are commonly detected by skin scrape tests or superficial biopsies. A new high-definition optical coherence tomography (HD-OCT) with high lateral and axial resolution in a horizontal (en-face) and vertical (slice) imaging mode might offer the possibility of noninvasive and fast in vivo examination of demodex mites. Methods: Twenty patients with demodex-related skin diseases and 20 age- and gender-matched healthy controls we...
Maier, T.; Sattler, E.; Braun-falco, M.; Ruzicka, Thomas; Berking, C.
Assessing atherosclerotic plaque morphology: comparison of optical coherence tomography and high frequency intravascular ultrasound.
BACKGROUND: OCT can image plaque microstructure at a level of resolution not previously demonstrated with other imaging techniques because it uses infrared light rather than acoustic waves. OBJECTIVES: To compare optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging of in vitro atherosclerotic plaques. METHODS: Segments of abdominal aorta were obtained immediately before postmortem examination. Images of 20 sites from five patients were acquired with OCT (operating at...
Brezinski, M. E.; Tearney, G. J.; Weissman, N. J.; Boppart, S. A.; Bouma, B. E.; Hee, M. R.; Weyman, A. E.; Swanson, E. A.; Southern, J. F.; Fujimoto, J. G.
Polarization memory effect in optical coherence tomography and dental imaging application
We report the existence of polarization memory effect (PME) in optical coherence tomography and investigate its potential applications in dental imaging. We performed the study in three steps. First, microsphere scattering phantoms of different sizes were imaged in order to validate experimental results with PME theory. Both linearly and circularly polarized light were used to probe the samples. Second, healthy tooth samples were scanned and polarization memory effect was identified in dentin...
Chen, Yueli; Otis, Linda; Zhu, Quing
Optical coherence tomography-current technology and applications in clinical and biomedical research
Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. By mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as birefringence, motion, or the distributions of certain substances can be detected with high spatial resolution. Its main field of application is biomedical imaging and diagnostics. In ophthalmolog...
Marschall, Sebastian; Sander, Birgit; Mogensen, Mette; J�rgensen, Thomas Martini; Andersen, Peter E.
Optical coherence tomography and Raman spectroscopy of the ex-vivo retina
Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analysis afforded by Raman scattering could provide critical molecular signatures for clinicians and researchers, there are many technical challenges to combine these imaging modalities. We describe an ...
Evans, Julia W.; Zawadzki, Robert J.; Liu, Rui; Chan, James W.; Lane, Stephen M.; Werner, John S.
Quantification of fiber orientation in the canine atrial pacemaker complex using optical coherence tomography
The atrial pacemaker complex is responsible for the initiation and early propagation of cardiac impulses. Optical coherence tomography (OCT), a nondestructive imaging modality with spatial resolutions of ?1 to 15�?m, can be used to identify unique fiber orientation patterns in this region of the heart. Functionally characterized canine sinoatrial nodes (SAN) (n=7) were imaged using OCT up to ?1??mm below the endocardial tissue surface. OCT images were directly compared to their corr...
Ambrosi, Christina M.; Fedorov, Vadim V.; Schuessler, Richard B.; Rollins, Andrew M.; Efimov, Igor R.
Noninvasive Monitoring of Breast Cancer during Neoadjuvant Chemotherapy Using Optical Tomography with Ultrasound Localization12
The purposes of this study were 1) to investigate the feasibility of using optical tomography in the near-infrared (NIR) spectrum combined with ultrasound (US) localization (NIR/US) in monitoring tumor vascular changes and assessing tumor pathological response during chemotherapy and 2) to compare the accuracy of NIR/US with magnetic resonance imaging (MRI) in predicting residual cancer after neoadjuvant chemotherapy. Eleven female patients were studied during treatments with a combined image...
Parry-Romberg syndrome studied by spectral-domain optical coherence tomography.
Parry-Romberg syndrome is a rare disorder characterized by progressive hemifacial atrophy. Ophthalmic findings are characterized by enophthalmos, strabismus, nerve palsies, anisometropia, glaucoma, and angle abnormalities. Vision loss has also been reported due to retinal changes such as venous dilatation, disc edema, retinal edema, and retinal folds. The authors describe a case of Parry-Romberg syndrome with retinal alterations but a normal macula on spectral-domain optical coherence tomography. PMID:24477334
Raina, Usha K; Seth, Anisha; Gupta, Rajat; Goel, Neha; Gupta, Anika; Ghosh, Basudeb
High resolution spectral domain optical coherence tomography (OCT) images of Alstr�m Syndrome
Alstr�m syndrome (ALMS1) is a multisystemic disorder characterized by cone�rod dystrophy, hearing loss, obesity, insulin resistance and hyperinsulinemia, type 2 diabetes mellitus, dilated cardiomyopathy, and progressive hepatic and renal dysfunction.The cone-rod retinal dystrophy usually develops within a few weeks after birth. We examined a young boy with Alstrom by means of microperimetry MP-1 and optical coherence tomography (OCT) Spectral Domain.
Vingolo, Em; Salvatore, S.; Grenga, Pl; Maffei, P.; Milan, G.; Marshall, Jd
Reproducibility of Scleral Spur Identification and Angle Measurements Using Fourier Domain Anterior Segment Optical Coherence Tomography
Purpose. To evaluate intraobserver and interobserver agreement in locating the scleral spur landmark (SSL) and anterior chamber angle measurements obtained using Fourier Domain Anterior Segment Optical Coherence Tomography (ASOCT) images. Methods. Two independent, masked observers (SR and AZC) identified SSLs on ASOCT images from 31 eyes with open and nonopen angles. A third independent reader, NPB, adjudicated SSL placement if identifications differed by more than 80??m. Nine months later...
Cumba, Ricardo J.; Radhakrishnan, Sunita; Bell, Nicholas P.; Nagi, Kundandeep S.; Chuang, Alice Z.; Lin, Shan C.; Mankiewicz, Kimberly A.; Feldman, Robert M.
3D shape based reconstruction of experimental data in Diffuse Optical Tomography
Diffuse optical tomography (DOT) aims at recovering three-dimensional images of absorption and scattering parameters inside diffusive body based on small number of transmission measurements at the boundary of the body. This image reconstruction problem is known to be an ill-posed inverse problem, which requires use of prior information for successful reconstruction. We present a shape based method for DOT, where we assume a priori that the unknown body consist of disjoint subdomains with diff...
Reference spectrum extraction and fixed-pattern noise removal in optical coherence tomography
We present a new signal processing method that extracts the reference spectrum information from an acquired optical coherence tomography (OCT) image without a separate calibration step of reference spectrum measurement. The reference spectrum is used to remove the fixed-pattern noise that is a characteristic artifact of Fourier-domain OCT schemes. It was found that the conventional approach based on an averaged spectrum, or mean spectrum, is prone to be influenced by the high-amplitude data p...
Moon, Sucbei; Lee, Sang-won; Chen, Zhongping
Use of Split Bregman denoising for iterative reconstruction in fluorescence diffuse optical tomography
Fluorescence diffuse optical tomography (fDOT) is a noninvasive imaging technique that makes it possible to quantify the spatial distribution of fluorescent tracers in small animals. fDOT image reconstruction is commonly performed by means of iterative methods such as the algebraic reconstruction technique (ART). The useful results yielded by more advanced l1-regularized techniques for signal recovery and image reconstruction, together with the recent publication of Split Bregman (SB) procedu...
Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography
We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggregation characteristics induced by dextran 500 or at the presence of plasma fibrinogen was measured ...
Towards using spectral domain optical coherence tomography for dental wear monitoring
In this paper we demonstrate that fast spectral domain optical coherence tomography imaging systems have the potential to monitor the evolution of pathological dental wear. On 10 caries free teeth, four levels of artificially defects similar to those observed in the clinic were created. After every level of induced defect, OCT scanning was performed. B-scans were acquired and 3D reconstructions were generated.
M?rc?uteanu, Corina; Bradu, Adrian; Sinescu, Cosmin; Topal?, Florin I.; Negrutiu, Meda Lavinia; Podoleanu, Adrian G.
Optical coherence tomography fast versus regular macular thickness mapping in diabetic retinopathy
Objective: The purpose of the study was to investigate if absolute values and reproducibility of thickness maps obtained from 2 optical coherence tomography (OCT) scanning protocols, regular high-resolution and fast low-density mode, differ in patients with diabetic macular edema. Methods: A total of 26 consecutive patients undergoing fluorescein angiography and Stratus OCT scanning for the evaluation of diabetic macular edema at the Departments of Ophthalmology in Munich and Vienna were incl...
Optical coherence tomography versus visual evoked potential in multiple sclerosis patients
Background: Optical coherence tomography (OCT) is anon-invasive instrument, which can be used to estimate thethickness of the retinal nerve fibre layer (RNFL) and providesan indirect measurement of axonal destruction in multiplesclerosis (MS). The main aim of this study was to find out anycorrelations between P100 latency in visual evokedpotential (VEP) and RNFL thickness.Methods: The patients with the definite history of opticneuritis regardless of the diagnosis of MS were included. Theeyes ...
Farzad Fatehi; Vahid Shaygannejad; Lida Kiani Mehr; Alireza Dehghani
Complex conjugate resolved heterodyne swept source optical coherence tomography using coherence revival
We describe a simple and low-cost technique for resolving the complex conjugate ambiguity in Fourier domain optical coherence tomography (OCT) that is applicable to many swept source OCT (SSOCT) systems. First, we review the principles of coherence revival, wherein an interferometer illuminated by an external cavity tunable laser (ECTL) exhibits interference fringes when the two arms of the interferometer are mismatched by an integer multiple of the laser cavity length. Second, we report obse...
Imaging of the retinal nerve fibre layer with spectral domain optical coherence tomography for glaucoma diagnosis
Optical coherence tomography (OCT) techniques have been applied to develop a new generation of the technology, called spectral domain (SD) or Fourier domain (FD) OCT. The commercially available SD-OCT technology offers benefits over the conventional time domain (TD) OCT such as a scanning speed up to 200 times faster and higher axial resolution (3 to 6 ?m). Overall, SD-OCT offers improved performance in terms of reproducibility. SD-OCT has a level of discriminating capability, between health...
Optical coherence tomography for quality assessment of embedded microchannels in alumina ceramic
Large-scale and cost-effective manufacturing of ceramic micro devices based on tape stacking requires the development of inspection systems to perform high-resolution in-process quality control of embedded manufactured cavities, metal structures and defects. With an optical coherence tomography (OCT) system operating at 1.3 mu m and a dedicated automated line segmentation algorithm, layer thicknesses can be measured and laser-machined channels can be verified in alumina ceramics embedded at a...
Full Text Available A High Speed Optical Coherence Tomography (OCT system based on single mode fiber which can capture eight images per second was used to acquire real time OCT images of human finger in vivo. The axial resolution of the set up was estimated to be 18 ?m. With this OCT images, the thickness of stratum corneum of the fingertip, finger pad and finger nail is evaluated.
S. Kumari
High-definition optical coherence tomography: adapted algorithmic method for pattern analysis of inflammatory skin diseases: a pilot study
High-definition optical coherence tomography (HD-OCT) is a non-invasive technique for morphological investigation of tissue with cellular resolution filling the imaging gap between reflectance confocal microscopy and conventional optical coherence tomography. The aim of this study is first to correlate dermatopathologic descriptors of inflammatory skin conditions with epidermal alteration to features observed by HD-OCT. Secondly, to assess the discriminative accuracy of common inflammatory re...
Boone, Marc; Norrenberg, Sarah; Jemec, Gregor; Del Marmol, Ve?ronique
Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system
Advances in optical imaging modalities, such as optical coherence tomography (OCT), enable us to observe tissue microstructure at high resolution and in real time. Currently, core-needle biopsies are guided by external imaging modalities such as ultrasound imaging and x-ray computed tomography (CT) for breast and lung masses, respectively. These image-guided procedures are frequently limited by spatial resolution when using ultrasound imaging, or by temporal resolution (rapid real-time feedba...
Mid-ventricular tako-tsubo cardiomyopathy with structurally normal coronary arteries confirmed by optical coherence tomography.
Tako-Tsubo cardiomyopathy is an entity of unknown etiology characterized by transient apical dyskinesia in patients with angiographically normal coronary arteries. However, atypical forms of Tako-Tsubo cardiomyopathy may also occur, affecting other myocardial segments. Optical coherence tomography has a unique resolution and may detect angiographically silent atherosclerotic coronary artery disease. In this report, we describe optical coherence tomography findings in a patient with atypical Tako-Tsubo cardiomyopathy presenting as transient mid-ventricular ballooning. PMID:24296394
Alfonso, Fernando; C�rdenas, Alberto; Ib��ez, Borja
In vivo, label-free, three-dimensional quantitative imaging of kidney microcirculation using Doppler optical coherence tomography (DOCT)
Doppler optical coherence tomography (DOCT) is a functional extension of optical coherence tomography (OCT) and is currently being employed in several clinical arenas to quantify blood flow in vivo. In this study, the objective was to investigate the feasibility of DOCT to image kidney microcirculation, specifically, glomerular blood flow. DOCT is able to capture 3D data sets consisting of a series of cross-sectional images in real time, which enables label-free and non-destructive quantifica...
Edema macular qu�stico pseudof�quico: Detecci�n mediante �optical coherence tomography� / Pseudophakic cystoid macular edema: Assesment with optical coherence tomography
Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Objetivo: Detectar la incidencia de edema macular qu�stico (EMQ) tras cirug�a de catarata tanto cl�nico como subcl�nico, mediante �ocular coherence tomography� (OCT) y comparar dicha incidencia entre un grupo de pacientes diab�ticos y otro de no diab�ticos. Material y m�todos: Estudio prospectivo de [...] 260 ojos intervenidos de forma consecutiva de catarata mediante facoemulsificaci�n con implante de lente intraocular acr�lica, desde septiembre de 2004 a marzo de 2005. Grupo A: 208 ojos de pacientes no diab�ticos, grupo B: 42 ojos de pacientes diab�ticos, grupo C: 10 ojos de pacientes diab�ticos con edema macular y que recibieron triamcinolona intrav�trea (TAIV) al finalizar la cirug�a. En cada revisi�n efectuada a los 6 d�as (basal), 5 semanas y 12 semanas se realiz� biomicroscop�a de polo posterior y OCT. Resultados: El espesor macular en la OCT, fue significativamente superior en el grupo B que en el grupo A (241,6 versus 204,6 �m p- 43,74 �m (2 DE del valor basal del grupo A). En el grupo B, seis ojos presentaron EMQ cl�nicamente significativo, con disminuci�n de agudeza visual (14,2%), en 12 ojos detectamos aumento del espesor macular (28,5%). Las diferencias entre grupos fueron significativas (p Abstract in english Purpose: To determine the incidence of cystoid macular edema (CME) by means of clinical evaluation and subclinical assessment by means of ocular coherence tomography (OCT), and to compare the incidence between diabetic and non-diabetic groups of patients. Methods: Prospective study of 260 consecutiv [...] e cataract surgeries operated from September 2004 to March 2005. The procedures were performed by means of phacoemulsification plus intraocular acrylic lens implantation. Group A: 208 eyes of non-diabetic patients; Group B: 42 eyes of patients with diabetes and Group C: 10 eyes of diabetic patients with macular edema that received an intravitreal injection of triamcinolone at the end of surgery. Postoperative follow-up visits were performed 6 days (basal visit), 5 weeks and 12 weeks after surgery. Each visit included posterior pole biomicroscopy and OCT. Results: Central macular thickness measured by OCT was significantly increased in group B compared with group A (241.6 versus 204.6 �m; p
C., Torr�n-Fern�ndez-Blanco; O., Ruiz-Moreno; E., Ferrer-Novella; A., S�nchez-Cano; F.M., Honrubia-L�pez.
Scatter measurements for optical cone-beam computed tomography
Both x-ray and optical cone-beam CT (CBCT) scanners are limited by scattered photons that contaminate the primary images. Transparent radiochromic gels and plastics are anticipated to produce less scattering than polymerization gels and hence result in reconstructed dose distributions with greater contrast and dynamic range. Four methods of scatter measurement were investigated to quantify scatter fractions using an in-house optical CBCT scanner. The methods consisted of generating either 'coin' shadows or primary beamlets in transmission images. The four methods generated similar results of 10% scatter fractions in gel transmission images for this particular scanner configuration with both leuco crystal violet and carbon black micelle gels. The scatter contributions were distributed as 5% from micelle gel, 2% from Teflon wall, 2% from refractive index matching liquid and 1% other sources. Applying a uniform background subtraction of 2% of open field intensity resulted in 0.2% difference between laser CT and cone-beam CT reconstructed attenuation coefficients for a black micelle gel finger phantom.
Jordan, Kevin; Battista, Jerry [London Regional Cancer Program, London Health Sciences Centre and Department of Medical Biophysics, University of Western Ontario, London, ON (Canada)], E-mail: firstname.lastname@example.com
Automatic Detection of Glaucoma Using Optical Coherence Tomography Image
Full Text Available Glaucoma is an eye disorder in which the optic nerve suffers damage, leading to vision defect in the affected eye(s and rolling to complete blindness if untreated. It is frequently associated with increased pressure in the fluid of the eye; aqueous humour. Glaucoma often goes undetected until significant damage to the subject�s visual field has occurred. As glaucoma progresses, neural tissues die, the nerve fiber layer thins and the cup-to-disk ratio increases. The conventional techniques typically used for this measurement are unreliable and creates intricacies while measuring considerably small changes in the nerve head geometry. In this study, an algorithm is proposed that facilitates segmentation of the retinal-nerve head vitreal boundary, choroid-nerve head boundary identification and determination of the extent of the optic cup and disk. This algorithm is assessed and evaluated with many samples of OCT images from both normal and pathological eyes. Subsequently, the results are validated with the available documents from expert ophthalmologist reporting the correlation coefficient for cup to disk ratio.
Rengaraj Venkatesh
Flow of blood-saline mixtures studied by time-domain optical coherence tomography
In-vitro analysis of flowing blood-saline mixtures is performed by time-domain optical coherence tomography imaging. The mixtures contain blood in concentrations ranging from 100% to 20%. For each image, a corresponding compounded profile is obtained by adding one thousand adjacent A-scans. The compounded profiles are used for characterizing the optical coherence tomography signal as it propagates within the studied blood-saline mixtures. The results obtained point toward the possibility of acquiring intra-vascular images of arterial tissue that is located behind slabs of flowing blood-saline. A threshold in the propagation distance beyond which the recorded signal becomes dominated by its multiple scattered components is established along the compounded profiles. The threshold location, at a depth of ~0.6 mm, is independent of blood concentration. Further investigation of the compounded profiles reveals that the region extending to a maximum depth of about 200 ?m from the point where the probing beam enters blood-saline mixtures could reveal information about the flow regime. This opens the possibility of another application for time-domain optical coherence tomography in intravascular imaging: assessing the flow regime, i.e. laminar or turbulent.
Popescu, Dan P.; Sowa, Michael G.
The complementary benefit of anterior segment optical coherence tomography in penetrating keratoplasty
Full Text Available Nursal Melda Yenerel,1 Raciha Beril Kucumen,2 Ebru Gorgun3 1Haydarpasa Numune Research and Training Hospital, Istanbul, Turkey; 2Yeditepe University Medical Faculty, Department of Ophthalmology, Istanbul, Turkey; 3Dunya Goz Eye Hospital, Istanbul, Turkey Purpose: To evaluate the utility of anterior segment optical coherence tomography (AS-OCT assessment in the pre- and postsurgical management of full-thickness corneal grafts. Methods: Seventy eyes of 58 patients who had penetrating keratoplasty were included in the study. High resolution AS-OCT scans of the cornea and the anterior segment were performed before and after transplantation in 17 eyes with the VisanteTM optical coherence tomography. Fifty-three eyes were examined in the late postoperative period. Results: The mean follow-up was 4.3 years (range, 1�15 years. Six different graft�host junctions were identified. Three patients with graft rejection, four patients with anterior synechia, and three patients with corneal ulcer were evaluated. Preoperative evaluation of eyes with semiopaque and totally opaque corneas revealed important information about anterior segment structures additional to slit-lamp findings. Conclusion: AS-OCT is a useful complementary tool for the evaluation of penetrating corneal transplantation surgery and in the management of its postoperative complications. Keywords: anterior segment optical coherence tomography, imaging techniques, penetrating keratoplasty
Yenerel NM
Optical coherence tomography in presumed subretinal Toxocara granuloma: case report Tomografia de coer�ncia �ptica em granuloma sub-retiniano por Toxocara: relato de caso
Our aim was to study optical coherence tomographic findings in a case of Toxocara granuloma. A patient with a cicatricial macular lesion, diagnosed as ocular toxocariasis, was examined with optical coherence tomography. In optical coherence tomography images, the macular granuloma appeared as a highly reflective round mass protruding above the retinal pigment epithelium with two other surrounding masses. Optical coherence tomography may increase understanding of the pathophysiology of the ret...
Aline do Lago; Rafael Andrade; Cristina Muccioli; Rubens Belfort Jr
Light-shift tomography in an optical-dipole trap for neutral atoms
We report on light-shift tomography of a cloud of 87 Rb atoms in a far-detuned optical-dipole trap at 1565 nm. Our method is based on standard absorption imaging, but takes advantage of the strong light-shift of the excited state of the imaging transition, which is due to a quasi-resonance of the trapping laser with a higher excited level. We use this method to (i) map the equipotentials of a crossed optical-dipole trap, and (ii) study the thermalisation of an atomic cloud by following the evolution of the potential-energy of atoms during the free-evaporation process.
Brantut, Jean-Philippe; Vincent, Martin Robert De Saint; Varoquaux, Gael; Nyman, Robert A; Aspect, Alain; Bourdel, Thomas; Bouyer, Philippe
Calibration-free B-scan images produced by master/slave optical coherence tomography
We report on a novel method to produce B-scan images in spectral domain optical coherence tomography (SD-OCT). The method proceeds in two steps. In the first step, using a mirror in the sample arm of the interferometer, channelled spectra are acquired for different values of the optical path difference (OPD) and stored as masks. In the second step, the mirror is replaced with an object and the captured channelled spectrum is correlated with each mask, providing the interference strength from ...
Multispectral in vivo three-dimensional optical coherence tomography of human skin
The capability of optical coherence tomography (OCT) to perform "optical biopsy" of tissues within a depth range of 1 to 2 mm with micron-scale resolution in real time makes it a promising biomedical imaging modality for dermatologic applications. Three highspeed, spectrometer-based frequency-domain OCT systems operating at 800 nm (20,000 A-scans/s), 1060 nm, and 1300 nm (both 47,000 A-scans/s) at comparable signal-to-noise ratio (SNR), SNR roll-off with scanning depth, and transverse...
Online monitoring of printed electronics by Spectral-Domain Optical Coherence Tomography
Spectral-Domain Optical Coherence Tomography (SD-OCT) is an optical method capable of 3D imaging of object's internal structure with micron-scale resolution. Modern SD-OCT tools offer the speed capable of online monitoring of printed devices. This paper demonstrates the use of SD-OCT in a simulated roll-to-roll (R2R) process through monitoring some structural properties of moving screen printed interdigitated electrodes. It is shown that structural properties can be resolved for speeds up to ...
Alarousu, Erkki; Alsaggaf, Ahmed; Jabbour, Ghassan E.
An all-at-once reduced Hessian SQP algorithm for frequency domain optical tomography
We introduce in this work a PDE-constrained approach to optical tomography that makes use of an all-atonce reduced Hessian Sequential Quadratic Programming (rSQP) scheme. The proposed scheme treats the forward and inverse variables independently, which makes it possible to update the radiation intensities and the optical coefficients simultaneously by solving the forward and inverse problems, all at once. We evaluate the performance of the proposed scheme with numerical and experimental data, and find that the rSQP scheme can reduce the computation time by a factor of 10 to 25, as compared to the commonly employed limited memory BFGS method.
Kim, Hyun Keol; Gu, Xuejun; Hielscher, Andreas H.
We report on light-shift tomography of a cloud of 87 Rb atoms in a far-detuned optical-dipole trap at 1565 nm. Our method is based on standard absorption imaging, but takes advantage of the strong light-shift of the excited state of the imaging transition, which is due to a quasi-resonance of the trapping laser with a higher excited level. We use this method to (i) map the equipotentials of a crossed optical-dipole trap, and (ii) study the thermalisation of an atomic cloud by following the ev...
Flicker-induced changes in retinal blood flow assessed by Doppler optical coherence tomography
We used Doppler Fourier-domain optical coherence tomography (OCT) to investigate flicker-induced changes of total retinal blood flow. Total retinal blood flow was measured by summing flows in veins imaged in double-circular scans around the optic disc. In 3 healthy volunteers, total retinal blood flow was measured before and 10-15 seconds after 30 seconds of flicker stimulation. The average blood flow increased 22.2% (p = 0.002). The total venous and arterial vessel cross-sectional area incre...
In vivo lung microvasculature visualized in three dimensions using fiber-optic color Doppler optical coherence tomography
For the first time, the use of fiber-optic color Doppler optical coherence tomography (CDOCT) to map in vivo the three-dimensional (3-D) vascular network of airway segments in human lungs is demonstrated. Visualizing the 3-D vascular network in the lungs may provide new opportunities for detecting and monitoring lung diseases such as asthma, chronic obstructive pulmonary disease, and lung cancer. Our CDOCT instrument employs a rotary fiber-optic probe that provides simultaneous two-dimensional (2-D) real-time structural optical coherence tomography (OCT) and CDOCT imaging at frame rates up to 12.5 frames per second. Controlled pullback of the probe allows 3-D vascular mapping in airway segments up to 50 mm in length in a single acquisition. We demonstrate the ability of CDOCT to map both small and large vessels. In one example, CDOCT imaging allows assignment of a feature in the structural OCT image as a large (�1 mm diameter) blood vessel. In a second example, a smaller vessel (�80 ?m diameter) that is indistinguishable in the structural OCT image is fully visualized in 3-D using CDOCT.
Lee, Anthony M. D.; Ohtani, Keishi; MacAulay, Calum; McWilliams, Annette; Shaipanich, Tawimas; Yang, Victor X. D.; Lam, Stephen; Lane, Pierre
Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics.
Cone photoreceptors in the living human eye have recently been imaged with micron-scale resolution in all three spatial dimensions using adaptive optics optical coherence tomography. While these advances have allowed non-invasive study of the three-dimensional structure of living human cones, studies of their function and physiology are still hampered by the difficulties to monitor the same cells over time. The purpose of this study is to demonstrate the feasibility of cone monitoring using ultrahigh-resolution adaptive optics optical coherence tomography. Critical to this is incorporation of a high speed CMOS camera (125 KHz) and a novel feature-based, image registration/dewarping algorithm for reducing the deleterious effects of eye motion on volume images. Volume movies were acquired on three healthy subjects at retinal eccentricities from 0.5� to 6�. Image registration/dewarping reduced motion artifacts in the movies from 15 ?m to 1.3 ?m root mean square, the latter sufficient for identifying and tracking cones. Cone row-to-row spacing and outer segment lengths were consistent with that reported in the literature. Cone length analysis demonstrates that UHR-AO-OCT is sufficiently sensitive to measure real length differences between cones in the same 0.5� retinal patch, and requires no more than five measurements of OS length to achieve 95% confidence. We know of no other imaging modality that can monitor foveal or parafoveal cones over time with comparable resolution in all three dimensions. PMID:21483600
Kocaoglu, Omer P; Lee, Sangyeol; Jonnal, Ravi S; Wang, Qiang; Herde, Ashley E; Derby, Jack C; Gao, Weihua; Miller, Donald T
Improvement of tissue analysis and classification using optical coherence tomography combined with Raman spectroscopy
Optical coherence tomography (OCT) is an optical imaging technique that is capable of performing high-resolution (approaching the histopathology level) and real-time imaging of tissues without use of contrast agents. Based on these advantages, the pathological features of tumors (in micro scale) can be identified during resection surgery. However, the accuracy of tumor margin prediction still needs to be enhanced for assisting the judgment of surgeons. In this regard, we present a two-dimensional computational method for advanced tissue analysis and characterization based on optical coherence tomography (OCT) and Raman spectroscopy (RS). The method combines the slope of OCT intensity signal and the Principal component (PC) of RS, and relies on the tissue optical attenuation and chemical ingredients for the classification of tissue types. Our pilot experiments were performed on mouse kidney, liver and small intestine. Results demonstrate the improvement of the tissue differentiation compared with the analysis only based on the OCT detection. This combined OCT/RS method is potentially useful as a novel optical biopsy technique for cancer detection.
Liu, Chih-Hao; Qi, Ji; Lu, Jing; Wang, Shang; Wu, Chen; Shih, Wei-Chuan; Larin, Kirill V.
Quantum states and measurements exhibit wave-like (continuous) or particle-like (discrete) character. Hybrid discrete-continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications such as entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to non-commuting observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parameterization to date in quantum tomography experiments, requiring the development of novel theoretical tools. Our results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors.
Zhang, Lijian; Coldenstrodt-Ronge, Hendrik B.; Datta, Animesh; Puentes, Graciana; Lundeen, Jeff S.; Jin, Xian-Min; Smith, Brian J.; Plenio, Martin B.; Walmsley, Ian A.
Two- and three-dimensional optical tomography of finger joints for diagnostics of rheumatoid arthritis
Rheumatoid arthritis (RA) is one of the most common diseases of human joints. This progressive disease is characterized by an inflammation process that originates in the inner membrane (synovalis) of the capsule and spreads to other parts of the joint. In early stages the synovalis thickness and the permeability of this membrane changes. This leads to changes in the optical parameters of the synovalis and the synovial fluid (synovia), which occupies the space between the bones. The synovia changes from a clear yellowish fluid to a turbid grayish substance. In this work we present 2 and 3-dimensional reconstruction schemes for optical tomography of the finger joints. Our reconstruction algorithm is based on the diffusion approximation and employs adjoint differentiation techniques for the gradient calculation of the objective function with respect to the spatial distribution of optical properties. In this way, the spatial distribution of optical properties within the joints is reconstructed with high efficiency and precision. Volume information concerning the synovial space and the capsula are provided. Furthermore, it is shown that small changes of the scattering coefficients can be monitored. Therefore, optical tomography has the potential of becoming a useful tool for the early diagnosis and monitoring of disease progression in RA.
Klose, Alexander D.; Hielscher, Andreas H.; Hanson, Kenneth M.; Beuthan, Juergen
Assessment of optical computed tomography for polymer gel dosimetry
Modern radiation therapy particularly with intensity modulation techniques (IMRT) offers the potential to improve patient outcomes by better limiting high doses to the tumour alone. IMRT delivery is technically complex, and precise verification of the resulting three dimensional (3D) dose is required to ensure that the objectives of the treatment are achieved. Currently no convenient dosimetry system exists for such 3D dosimetry. Gel dosimetry can provide the required verification system but is often limited because of access to imaging for dose determination. We present here results from the investigation of cone beam optical CT (optCT) for reading dose information in polymer gel systems. Various polymer gel dosimeters based on polyacrylamide gelatin (PAG) were prepared for this study; including some with the acrylamide replaced by N-vinylFormamide (PVFG), N-isopropyl acrylamide (NIPAM), or diacetone acrylamide (DAAM). The dosimeters incorporated an antioxidant to enable preparation in a conventional fumehood. Phantoms were irradiated with different conformal doses one day after dosimeter preparation with a Cobalt-60 tomotherapy benchtop on an MDS Nordion T-780 unit. Optical CT measurements were made on a prototype cone beam CT scanner (Vista Scanner, Modus Medical, London, ON). The scanner uses LEDs (at 590 or 633 nm) with a diffuser to provide a 9 deg. cone at a 1024x768 pixel, 10-bit, CCD camera. The acquisition time is roughly 8 min and image reconstruction (via a Feldkamp backprojection) takes a further 8 min. Each CT measurement consists of a pre-irradiation scan on the gel dosimeter phantom followed by scanning of the irradiated dosimeter at various times post irradiation. Each polymer gel phantom exhibited clear radiation induced polymerization apparent in visible light. Typical results of the optCT scanning are reviewed and discussed in the individual figure captions. In summary, the optical CT numbers are dose dependent and the reproducibility between multiple scans is very good. Thus, the Vista OptCT scanner with polymer gel dosimeters has the potential for convenient clinical application in IMRT dose-delivery validation. Further characterization is currently underway
Quantitative diffuse optical tomography for small animals using an ultrafast gated image intensifier.
The quantitative accuracy of fluorescence and bioluminescence imaging of small animals can be improved by knowledge of the in situ optical properties of each animal. Obtaining in situ optical property maps is challenging, however, due to short propagation distances, requirements for high dynamic range, and the need for dense spatial, temporal, and spectral sampling. Using an ultrafast gated image intensifier and a pulsed laser source, we have developed a small animal diffuse optical tomography system with multiple synthetic modulation frequencies up to >1 GHz. We show that amplitude and phase measurements with useful contrast-to-noise ratios can be obtained for modulation frequencies over the range of approximately 250 to 1250 MHz. Experiments with tissue simulating phantoms demonstrate the feasibility of reconstructing the absorption and scattering optical properties in a small animal imaging system. PMID:18315358
Patwardhan, Sachin V; Culver, Joseph P
Versatile Wideband Balanced Detector for Quantum Optical Homodyne Tomography
We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with pulse repetition rates up to about 250 MHz.
Kumar, Ranjeet; MacRae, Andrew; Cairns, E; Huntington, E H; Lvovsky, A I
Time resolved optical tomography of the human forearm
A 32-channel time-resolved optical imaging instrument has been developed principally to study functional parameters of the new-born infant brain. As a prelude to studies on infants, the device and image reconstruction methodology have been evaluated on the adult human forearm. Cross-sectional images were generated using time-resolved measurements of transmitted light at two wavelengths. All data were acquired using a fully automated computer-controlled protocol. Images representing the internal scattering and absorbing properties of the arm are presented, as well as images that reveal physiological changes during a simple finger flexion exercise. The results presented in this paper represent the first simultaneous tomographic reconstruction of the internal scattering and absorbing properties of a clinical subject using purely temporal data, with additional co-registered difference images showing repeatable absorption changes at two wavelengths in response to exercise. (author)
Hillman, Elizabeth M.C.; Hebden, Jeremy C.; Schweiger, Martin; Dehghani, Hamid; Schmidt, Florian E.W.; Delpy, David T. [Department of Medical Physics and Bioengineering, University College London, 11-20 Capper Street, London WC1E 6JA (United Kingdom); Arridge, Simon R. [Department of Computer Science, University College London, Gower Street, London WC1E 6BT (United Kingdom)
The potential optical coherence tomography in tooth bleaching quantitative assessment
In this paper, we report the outcomes from a pilot study on using OCT functional imaging method to evaluate and quantify color alteration in the human teeth in vitro. The image formations of the dental tissues without and with treatment 35% hydrogen peroxide were obtained by an OCT system at a 1310 nm central wavelength. One parameter for the quantification of optical properties from OCT measurements is introduced in our study: attenuate coefficient (?). And the attenuate coefficient have significant decrease ( p tooth bleaching process. From the experimental results, it is found that attenuate coefficient could be useful to assess color alteration of the human tooth samples. OCT has a potential to become an effective tool for the assessment tooth bleaching. And our experiment offer a now method to evaluate color change in visible region by quantitative analysis of the infrared region information from OCT.
Hyperspectral and multispectral bioluminescence optical tomography for small animal imaging
For bioluminescence imaging studies in small animals, it is important to be able to accurately localize the three-dimensional (3D) distribution of the underlying bioluminescent source. The spectrum of light produced by the source that escapes the subject varies with the depth of the emission source because of the wavelength-dependence of the optical properties of tissue. Consequently, multispectral or hyperspectral data acquisition should help in the 3D localization of deep sources. In this paper, we describe a framework for fully 3D bioluminescence tomographic image acquisition and reconstruction that exploits spectral information. We describe regularized tomographic reconstruction techniques that use semi-infinite slab or FEM-based diffusion approximations of photon transport through turbid media. Singular value decomposition analysis was used for data dimensionality reduction and to illustrate the advantage of using hyperspectral rather than achromatic data. Simulation studies in an atlas-mouse geometry indicated that sub-millimeter resolution may be attainable given accurate knowledge of the optical properties of the animal. A fixed arrangement of mirrors and a single CCD camera were used for simultaneous acquisition of multispectral imaging data over most of the surface of the animal. Phantom studies conducted using this system demonstrated our ability to accurately localize deep point-like sources and show that a resolution of 1.5 to 2.2 mm for depths up to 6 mm can be achieved. We also include an in vivo study of a mouse with a brain tumour expressing firefly luciferase. Co-registration of the reconstructed 3D bioluminescent image with magnetic resonance images indicated good anatomical localization of the tumour.
Chaudhari, Abhijit J [Signal and Image Processing Institute, Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, CA 90089 (United States); Darvas, Felix [Signal and Image Processing Institute, Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, CA 90089 (United States); Bading, James R [Department of Radiology, University of Southern California, Los Angeles, CA 90033 (United States); Moats, Rex A [Department of Radiology, University of Southern California, Los Angeles, CA 90033 (United States); Conti, Peter S [Department of Radiology, University of Southern California, Los Angeles, CA 90033 (United States); Smith, Desmond J [Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, CA 90095 (United States); Cherry, Simon R [Department of Biomedical Engineering, University of California-Davis, Davis, CA 95616 (United States); Leahy, Richard M [Signal and Image Processing Institute, Department of Electrical Engineering-Systems, University of Southern California, Los Angeles, CA 90089 (United States)
For bioluminescence imaging studies in small animals, it is important to be able to accurately localize the three-dimensional (3D) distribution of the underlying bioluminescent source. The spectrum of light produced by the source that escapes the subject varies with the depth of the emission source because of the wavelength-dependence of the optical properties of tissue. Consequently, multispectral or hyperspectral data acquisition should help in the 3D localization of deep sources. In this paper, we describe a framework for fully 3D bioluminescence tomographic image acquisition and reconstruction that exploits spectral information. We describe regularized tomographic reconstruction techniques that use semi-infinite slab or FEM-based diffusion approximations of photon transport through turbid media. Singular value decomposition analysis was used for data dimensionality reduction and to illustrate the advantage of using hyperspectral rather than achromatic data. Simulation studies in an atlas-mouse geometry indicated that sub-millimeter resolution may be attainable given accurate knowledge of the optical properties of the animal. A fixed arrangement of mirrors and a single CCD camera were used for simultaneous acquisition of multispectral imaging data over most of the surface of the animal. Phantom studies conducted using this system demonstrated our ability to accurately localize deep point-like sources and show that a resolution of 1.5 to 2.2 mm for depths up to 6 mm can be achieved. We also include an in vivo study of a mouse with a brain tumour expressing firefly luciferase. Co-registration of the reconstructed 3D bioluminescent image with magnetic resonance images indicated good anatomical localization of the tumour
Edema macular qu�stico pseudof�quico: Detecci�n mediante �optical coherence tomography� Pseudophakic cystoid macular edema: Assesment with optical coherence tomography
Full Text Available Objetivo: Detectar la incidencia de edema macular qu�stico (EMQ tras cirug�a de catarata tanto cl�nico como subcl�nico, mediante �ocular coherence tomography� (OCT y comparar dicha incidencia entre un grupo de pacientes diab�ticos y otro de no diab�ticos. Material y m�todos: Estudio prospectivo de 260 ojos intervenidos de forma consecutiva de catarata mediante facoemulsificaci�n con implante de lente intraocular acr�lica, desde septiembre de 2004 a marzo de 2005. Grupo A: 208 ojos de pacientes no diab�ticos, grupo B: 42 ojos de pacientes diab�ticos, grupo C: 10 ojos de pacientes diab�ticos con edema macular y que recibieron triamcinolona intrav�trea (TAIV al finalizar la cirug�a. En cada revisi�n efectuada a los 6 d�as (basal, 5 semanas y 12 semanas se realiz� biomicroscop�a de polo posterior y OCT. Resultados: El espesor macular en la OCT, fue significativamente superior en el grupo B que en el grupo A (241,6 versus 204,6 �m p- 43,74 �m (2 DE del valor basal del grupo A. En el grupo B, seis ojos presentaron EMQ cl�nicamente significativo, con disminuci�n de agudeza visual (14,2%, en 12 ojos detectamos aumento del espesor macular (28,5%. Las diferencias entre grupos fueron significativas (pPurpose: To determine the incidence of cystoid macular edema (CME by means of clinical evaluation and subclinical assessment by means of ocular coherence tomography (OCT, and to compare the incidence between diabetic and non-diabetic groups of patients. Methods: Prospective study of 260 consecutive cataract surgeries operated from September 2004 to March 2005. The procedures were performed by means of phacoemulsification plus intraocular acrylic lens implantation. Group A: 208 eyes of non-diabetic patients; Group B: 42 eyes of patients with diabetes and Group C: 10 eyes of diabetic patients with macular edema that received an intravitreal injection of triamcinolone at the end of surgery. Postoperative follow-up visits were performed 6 days (basal visit, 5 weeks and 12 weeks after surgery. Each visit included posterior pole biomicroscopy and OCT. Results: Central macular thickness measured by OCT was significantly increased in group B compared with group A (241.6 versus 204.6 �m; p<0,001. No clinical evidence of CME was found in group A, although 4 eyes (1.92% showed macular thickness equal to or greater than 43.74 �m (2 standard deviations of the basal value for group A. In group B, clinical evidence of CME was found in 6 eyes, with decreased visual acuities (14.2%. The differences between these groups were statistically significant (p<0.001. The 10 eyes that received an intravitreal injection of triamcinolone after the surgical procedure showed a mean decrease in central retinal thickness of 77 �m after 12 weeks postoperative. Conclusions: This study has shown a low incidence of clinical CME. OCT showed increased macular thickness in both groups of patients in a small percentage of cases, and significantly increased macular thickness in diabetic patients.
Spectral-domain optical coherence tomography staging and autofluorescence imaging in achromatopsia.
IMPORTANCE Evidence is mounting that achromatopsia is a progressive retinal degeneration, and treatments for this condition are on the horizon. OBJECTIVES To categorize achromatopsia into clinically identifiable stages using spectral-domain optical coherence tomography and to describe fundus autofluorescence imaging in this condition. DESIGN, SETTING, AND PARTICIPANTS A prospective observational study was performed between 2010 and 2012 at the Edward S. Harkness Eye Institute, New York-Presbyterian Hospital. Participants included 17 patients (aged 10-62 years) with full-field electroretinography-confirmed achromatopsia. MAIN OUTCOMES AND MEASURES Spectral-domain optical coherence tomography features and staging system, fundus autofluorescence and near-infrared reflectance features and their correlation to optical coherence tomography, and genetic mutations served as the outcomes and measures. RESULTS Achromatopsia was categorized into 5 stages on spectral-domain optical coherence tomography: stage 1 (2 patients [12%]), intact outer retina; stage 2 (2 patients [12%]), inner segment ellipsoid line disruption; stage 3 (5 patients [29%]), presence of an optically empty space; stage 4 (5 patients [29%]), optically empty space with partial retinal pigment epithelium disruption; and stage 5 (3 patients [18%]), complete retinal pigment epithelium disruption and/or loss of the outer nuclear layer. Stage 1 patients showed isolated hyperreflectivity of the external limiting membrane in the fovea, and the external limiting membrane was hyperreflective above each optically empty space. On near infrared reflectance imaging, the fovea was normal, hyporeflective, or showed both hyporeflective and hyperreflective features. All patients demonstrated autofluorescence abnormalities in the fovea and/or parafovea: 9 participants (53%) had reduced or absent autofluorescence surrounded by increased autofluorescence, 4 individuals (24%) showed only reduced or absent autofluorescence, 3 patients (18%) displayed only increased autofluorescence, and 1 individual (6%) exhibited decreased macular pigment contrast. Inner segment ellipsoid line loss generally correlated with the area of reduced autofluorescence, but hyperautofluorescence extended into this region in 2 patients (12%). Bilateral coloboma-like atrophic macular lesions were observed in 1 patient (6%). Five novel mutations were identified (4 in the CNGA3 gene and 1 in the CNGB3 gene). CONCLUSIONS AND RELEVANCE Achromatopsia often demonstrates hyperautofluorescence suggestive of progressive retinal degeneration. The proposed staging system facilitates classification of the disease into different phases of progression and may have therapeutic implications. PMID:24504161
Greenberg, Jonathan P; Sherman, Jerome; Zweifel, Sandrine A; Chen, Royce W S; Duncker, Tobias; Kohl, Susanne; Baumann, Britta; Wissinger, Bernd; Yannuzzi, Lawrence A; Tsang, Stephen H
Highlights: �New strategies to improve the accuracy of the reconstruction through mesh and finite element parameterization. �Use of gradient filtering through an alternative inner product within the adjoint method. �An integral form of the cost function is used to make the reconstruction compatible with all finite element formulations, continuous and discontinuous. �Gradient-based algorithm with the adjoint method is used for the reconstruction. -- Abstract: Optical tomography is mathematically treated as a non-linear inverse problem where the optical properties of the probed medium are recovered through the minimization of the errors between the experimental measurements and their predictions with a numerical model at the locations of the detectors. According to the ill-posed behavior of the inverse problem, some regularization tools must be performed and the Tikhonov penalization type is the most commonly used in optical tomography applications. This paper introduces an optimized approach for optical tomography reconstruction with the finite element method. An integral form of the cost function is used to take into account the surfaces of the detectors and make the reconstruction compatible with all finite element formulations, continuous and discontinuous. Through a gradient-based algorithm where the adjoint method is used to compute the gradient of the cost function, an alternative inner product is employed for preconditioning the reconstruction algorithm. Moreover, appropriate re-parameterization of the optical properties is performed. These regularization strategies are compared with the classical Tikhonov penalization one. It is shown that both the re-parameterization and the use of the Sobolev cost function gradient are efficient for solving such an ill-posed inverse problem.
Balima, O., E-mail: email@example.com [D�partement des Sciences Appliqu�es, Universit� du Qu�bec � Chicoutimi, 555 bd de l�Universit�, Chicoutimi, QC, Canada G7H 2B1 (Canada); Favennec, Y. [LTN UMR CNRS 6607 � Polytech� Nantes � La Chantrerie, Rue Christian Pauc, BP 50609 44 306 Nantes Cedex 3 (France); Rousse, D. [Chaire de recherche industrielle en technologies de l��nergie et en efficacit� �nerg�tique (t3e), �cole de technologie sup�rieure, 201 Boul. Mgr, Bourget L�vis, QC, Canada G6V 6Z3 (Canada)
Highlights: �New strategies to improve the accuracy of the reconstruction through mesh and finite element parameterization. �Use of gradient filtering through an alternative inner product within the adjoint method. �An integral form of the cost function is used to make the reconstruction compatible with all finite element formulations, continuous and discontinuous. �Gradient-based algorithm with the adjoint method is used for the reconstruction. -- Abstract: Optical tomography is mathematically treated as a non-linear inverse problem where the optical properties of the probed medium are recovered through the minimization of the errors between the experimental measurements and their predictions with a numerical model at the locations of the detectors. According to the ill-posed behavior of the inverse problem, some regularization tools must be performed and the Tikhonov penalization type is the most commonly used in optical tomography applications. This paper introduces an optimized approach for optical tomography reconstruction with the finite element method. An integral form of the cost function is used to take into account the surfaces of the detectors and make the reconstruction compatible with all finite element formulations, continuous and discontinuous. Through a gradient-based algorithm where the adjoint method is used to compute the gradient of the cost function, an alternative inner product is employed for preconditioning the reconstruction algorithm. Moreover, appropriate re-parameterization of the optical properties is performed. These regularization strategies are compared with the classical Tikhonov penalization one. It is shown that both the re-parameterization and the use of the Sobolev cost function gradient are efficient for solving such an ill-posed inverse problem
Three-dimensional non-destructive optical evaluation of laser-processing performance using optical coherence tomography
We demonstrate the use of optical coherence tomography (OCT) as a non-destructive diagnostic tool for evaluating laser-processing performance by imaging the features of a pit and a rim. A pit formed on a material at different laser-processing conditions is imaged using both a conventional scanning electron microscope (SEM) and OCT. Then using corresponding images, the geometrical characteristics of the pit are analyzed and compared. From the results, we could verify the feasibility and the potential of the application of OCT to the monitoring of the laser-processing performance.
Kim, Youngseop; Choi, Eun Seo; Kwak, Wooseop; Shin, Yongjin; Jung, Woonggyu; Ahn, Yeh-Chan; Chen, Zhongping
Apoptosis- and necrosis-induced changes in light attenuation measured by optical coherence tomography.
Optical coherence tomography (OCT) was used to determine optical properties of pelleted human fibroblasts in which necrosis or apoptosis had been induced. We analysed the OCT data, including both the scattering properties of the medium and the axial point spread function of the OCT system. The optical attenuation coefficient in necrotic cells decreased from 2.2 +/- 0.3 mm(1) to 1.3 +/- 0.6 mm(-1), whereas, in the apoptotic cells, an increase to 6.4 +/- 1.7 mm(-1) was observed. The results from cultured cells, as presented in this study, indicate the ability of OCT to detect and differentiate between viable, apoptotic, and necrotic cells, based on their attenuation coefficient. This functional supplement to high-resolution OCT imaging can be of great clinical benefit, enabling on-line monitoring of tissues, e.g. for feedback in cancer treatment. PMID:19756838
van der Meer, Freek J; Faber, Dirk J; Aalders, Maurice C G; Poot, Andre A; Vermes, Istvan; van Leeuwen, Ton G
Imaging osteoarthritis in the knee joints using x-ray guided diffuse optical tomography
In our previous studies, near-infrared (NIR) diffuse optical tomography (DOT) had been successfully applied to imaging osteoarthritis (OA) in the finger joints where significant difference in optical properties of the joint tissues was evident between healthy and OA finger joints. Here we report for the first time that large joints such as the knee can also be optically imaged especially when DOT is combined with x-ray tomosynthesis where the 3D image of the bones from x-ray is incorporated into the DOT reconstruction as spatial a priori structural information. This study demonstrates that NIR light can image large joints such as the knee in addition to finger joints, which will drastically broaden the clinical utility of our x-ray guided DOT technique for OA diagnosis.
Zhang, Qizhi; Yuan, Zhen; Sobel, Eric S.; Jiang, Huabei
Three-dimensional spectral domain optical coherence tomography in X linked foveal retinoschisis.
Spectral domain optical coherence tomography (SD-OCT) was performed in two cases of bilateral X linked foveal retinoschisis of different age groups. On fundus examination spoke wheel and honeycomb pattern of cysts were observed along with retinal nerve fibre layer (RNFL) defects. On SD-OCT, schisis was observed in the outer plexiform layer. External limiting membrane disruption was observed in the subfoveal area, along with disruption of outer nuclear layer (ONL) and inner-outer segment junction. Elevation of ONL due to tractional pull of central palisade was a novel observation. Retinoschisis extended beyond the optic disc up to the nasal region. Extracted RNFL tomogram presented an unprecedented visualisation of schisis along 360� of the optic disc. Tractional elevation in the foveal area and schisis involving nasal region, not observed upon clinical examination, was highlighted on SD-OCT. This investigative modality is an important adjunct in the assessment of foveal retinoschisis. PMID:23563673
Saxena, Sandeep; Manisha; Meyer, Carsten H
Algebraic reconstruction and postprocessing in one-step diffuse optical tomography
The photon average trajectory method is considered, which is used as an approximate method of diffuse optical tomography and is based on the solution of the Radon-like trajectory integral equation. A system of linear algebraic equations describing a discrete model of object reconstruction is once inverted by using a modified multiplicative algebraic technique. The blurring of diffusion tomograms is eliminated by using space-varying restoration and methods of nonlinear colour interpretation of data. The optical models of the breast tissue in the form of rectangular scattering objects with circular absorbing inhomogeneities are reconstructed within the framework of the numerical experiment from optical projections simulated for time-domain measurement technique. It is shown that the quality of diffusion tomograms reconstructed by this method is close to that of tomograms reconstructed by using Newton-like multistep algorithms, while the computational time is much shorter. (special issue devoted to application of laser technologies in biophotonics and biomedical studies)
Identification of prefrontal cortex (BA10) activation while performing Stroop test using diffuse optical tomography
Stroop test is commonly used as a behavior-testing tool for psychological examinations that are related to attention and cognitive control of the human brain. Studies have shown activations in Broadmann area 10 (BA10) of prefrontal cortex (PFC) during attention and cognitive process. The use of diffuse optical tomography (DOT) for human brain mapping is becoming more prevalent. In this study we expect to find neural correlates between the performed cognitive tasks and hemodynamic signals detected by a DOT system. Our initial observation showed activation of oxy-hemoglobin concentration in BA 10, which is consistent with some results seen by positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Our study demonstrates the possibility of combining DOT with Stroop test to quantitatively investigate cognitive functions of the human brain at the prefrontal cortex.
Khadka, Sabin; Chityala, Srujan R.; Tian, Fenghua; Liu, Hanli
The correlation between rat retinal nerve fiber layer thickness around optic disc by using optical coherence tomography and histological measurements
Full Text Available AIM:To explore the correlation between the retinal nerve fiber layer (RNFL thickness by using optical coherence tomography (OCT and by histological measurements in normal adult rats and optic nerve transected rats.METHODS:The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group (n=20 rats and the optic nerve transected group (n=16 rats. The latter group included 4 groups (n=4/group surviving for 1 day, 3, 5 and 7 days. Then the RNFL thickness of the same retina area was also measured by NF-200 immunohistochemical staining method. Linear regression was used to analyze the correlation between the data obtained from these two methods.RESULTS: The RNFL thickness of normal right eyes around optic disc by OCT was 72.35�5.71?m and that of the left eyes was 72.65�5.88?m (P=0.074. The RNFL thickness of the corresponding histological section by immunohistochemistry was 37.54�4.05?m (right eyes and 37.38�4.23?m (left eyes (P=0.059. There was a good correlation between the RNFL thickness measured by OCT and that measured by histology (R2=0.8131. After optic nerve transection, the trend of the RNFL thickness was thinner with the prolonged survival time. The correlation of the thickness detected by the above two methods was approximately (R2=0.8265. Value of the RNFL thickness in rats around optic disc measured by OCT was obviously higher than that measured by common histological measurement in normal adult rats and optic nerve transected rats.CONCLUSION: The RNFL thickness measured by OCT has a strong correlation with that measured by histological method. Through OCT scanning, we found that the thickness of RNFL gradually becomes thinner in a time-dependent manner.
Ju-Fang Huang
Fracture process characterization of fiber-reinforced dental composites evaluated by optical coherence tomography, SEM and optical microscopy
Full Text Available SciELO Brazil | Language: English Abstract in english This study used optical coherence tomography (OCT) compared to scanning electron microscopy (SEM) and optical microscopy (OM) to evaluate qualitatively crack propagation and final fracture in restorative composite materials - Filtek Z250 and Filtek Z350 (3M ESPE) - with fiber reinforcement after cyc [...] lic loading. Samples were made using a split mold. Initially, 3-point bending tests were performed to determine the maximum force and tension at the fracture moment using samples without fiber reinforcement. Then, mechanical cycling tests were performed using samples with glass fiber embedded internally. The failures were analyzed using the 3 methods described before. OCT permitted good characterization of internal crack propagation of the dental composites, which, however, could not be visualized by either SEM or OM. OCT was proven to be laboratory research tool that is easy to use, does not require any specific preparation of the samples, and is less expensive than SEM.
Tib�rio C. U., Matheus; Cynthia M. F., Kauffman; Ana K. S., Braz; Cl�udia C. B. O., Mota; Anderson S. L., Gomes.
A theoretical framework for the analysis of optical anisotropy in birefringent biological tissues with polarization-sensitive optical coherence tomography
Polarization-sensitive optical coherence tomography (PSOCT) has established itself as an important non-invasive optical imaging tool to study the birefringent biological tissues. The complex 3D structure architecture of the collagen fibers in articular cartilage is investigated using a time domain PSOCT (TD-PSOCT) system and the depth-wise cumulative retardance profiles obtained are compared with a three layer cartilage model. The PSOCT result obtained from the variable incidence angle (VIA) experiment of bovine cartilage sample is found to be consistent with the proposed lamellar cartilage model based on scanning electron microscope studies. This shows potential use of PSOCT -VIA technique to obtain depth-wise information about the complex 3D architecture of collagen fibers in the cartilage. Further studies would have to be carried out to map out depth wise retardance information at different sites of the cartilage, which could establish the general validity of this approach.
Kasaragod, Deepa K.; Lu, Zenghai; Jacobs, James; Matcher, Stephen J.
Repeatability of in vivo 3D lamina cribrosa microarchitecture using adaptive optics spectral domain optical coherence tomography.
We demonstrate the repeatability of lamina cribrosa (LC) microarchitecture for in vivo 3D optical coherence tomography (OCT) scans of healthy, glaucoma suspects, and glaucomatous eyes. Eyes underwent two scans using a prototype adaptive optics spectral domain OCT (AO-SDOCT) device from which LC microarchitecture was semi-automatically segmented. LC segmentations were used to quantify pore and beam structure through several global microarchitecture parameters. Repeatability of LC microarchitecture was assessed qualitatively and quantitatively by calculating parameter imprecision. For all but one parameters (pore volume) measurement imprecision was <4.7% of the mean value, indicating good measurement reproducibility. Imprecision ranged between 27.3% and 54.5% of the population standard deviation for each parameter, while there was not a significant effect on imprecision due to disease status, indicating utility in testing for LC structural trends. PMID:24761293
Nadler, Zach; Wang, Bo; Wollstein, Gadi; Nevins, Jessica E; Ishikawa, Hiroshi; Bilonick, Richard; Kagemann, Larry; Sigal, Ian A; Ferguson, R Daniel; Patel, Ankit; Hammer, Daniel X; Schuman, Joel S
Study of continuous-wave domain fluorescence diffuse optical tomography for quality control on agricultural produce
The importance of monitoring the quality of vegetables and fruits is prosperity by giving a competitive advantage for producer and providing a more healthy food for consumer. Diffuse Optical Tomography (DOT) is offering the possibility to detect the internal defects of the agricultural produce quality. Fluorescence diffuse optical tomography (FDOT) is the development of DOT, offering the possibilities to improve spatial resolution and to contrast image. The purpose of this research is to compare FDOT and DOT in forward analysis with continuous wave approach. The scattering and absorbing parameters of potatoes are used to represent the real condition. The object was illuminated by the NIR source from some positions on the boundary of object. A set of NIR detector are placed on the peripheral position of the object to measure the intensity of propagated or emitted light. In the simulation, we varied a condition of object then we analyzed the sensitivity of forward problem. The result of this study shows that FDOT has a better sensitivity than DOT and a better potential to monitor internal defects of agricultural produce because of the contrast value between optical and fluorescence properties of agricultural produce normal tissue and defects.
Nadhira, Vebi; Kurniadi, Deddy; Juliastuti, E.; Sutiswan, Adeline
Boundary conditions in the research of stress-strain state by optical tomography method
Mechanical stresses appear in the elastic body under the influence of external loading. In these conditions optical isotropic medium becomes optical anisotropic and behaves itself as a crystal. In photoelasticity on the analogy with a classification of natural crystal anisotropy three problems of the stress strain state can be distinguished. The tasks in which the stress strain state is caused by a uniform compression or expansion belong to the first problem. It is the most common case. The plane problems belong to the second group of problems. In this case stress strain state is described by the tensor of the second order with three or four components not equal to zero. All the rest problems belong to the third group. The stress strain state of the medium is described by the second order tensor with six components different from zero. The investigation of such problems required new transillumination schemes and algorithms for the treatment of experimental results which radically differ from the classical tomography schemes and methods. The role of boundary conditions for the correct formulation photoelasticity problems based on the restoration of tensor fields by means of optical tomography is presented in this article.
Patrikeyev, I.; Shakhurdin, V. [Perm State Technical Univ. (Russian Federation)
Anterior segment optical coherence tomography for demonstrating posterior capsular rent in posterior polar cataract
Full Text Available George D Kymionis,1,2 Vasilios F Diakonis,1 Dimitrios A Liakopoulos,1 Konstantinos I Tsoulnaras,1 Nektarios E Klados,1 Ioannis G Pallikaris11Institute of Vision and Optics, Department of Medicine, University of Crete, Heraklion, Crete, Greece; 2Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USAAims/purpose: To report the preoperative use of anterior segment optical coherence tomography (AS-OCT for the determination of pre-existing posterior capsule defect in patients with posterior polar cataract.Methods: Three patients presented with posterior polar cataract and were evaluated preoperatively using AS-OCT, revealing in one patient intact posterior capsule and in the other two a pre-existing posterior capsule defect not detectable by slit-lamp evaluation. All patients underwent phacoemulsification and intraocular lens implantation.Results: Intraoperatively, AS-OCT findings were confirmed after cataract surgery in all patients. No intra- or late postoperative complications were noted.Conclusion: AS-OCT could be an additional useful imaging modality in these patients, essential for surgical planning and patient consultation.Keywords: posterior capsular cataract, phacoemulsification, cataract complications, posterior capsular rupture, anterior segment optical coherence tomography
Kymionis GD
Reconstruction methods for sound visualization based on acousto-optic tomography
The visualization of acoustic fields using acousto-optic tomography has recently proved to yield satisfactory results in the audible frequency range. The current implementation of this visualization technique uses a laser Doppler vibrometer (LDV) to measure the acousto-optic effect, that is, the interaction between sound and light, over an aperture where the acoustic field is to be investigated. By identifying the relationship between the apparent velocity of the LDV and the Radon transform of the acoustic field, it is possible to reconstruct the sound pressure distribution of the scanned area using tomographic techniques. The filtered back projection (FBP) method is the most popular reconstruction algorithm used for tomography in many fields of science. The present study takes the performance of the FBP method in sound visualization as a reference and investigates the use of alternative methods commonly used in inverse problems, e.g., the singular value decomposition and the conjugate gradient methods. A generic formulation for describing the acousto-optic measurement as an inverse problem is thus derived, and the performance of the numerical methods is assessed by means of simulations and experimental results.
Torras Rosell, Antoni; Lylloff, Oliver
Comparison of diffusion approximation and higher order diffusion equations for optical tomography of osteoarthritis
In this study, a simplified spherical harmonics approximated higher order diffusion model is employed for 3-D diffuse optical tomography of osteoarthritis in the finger joints. We find that the use of a higher-order diffusion model in a stand-alone framework provides significant improvement in reconstruction accuracy over the diffusion approximation model. However, we also find that this is not the case in the image-guided setting when spatial prior knowledge from x-rays is incorporated. The results show that the reconstruction error between these two models is about 15 and 4%, respectively, for stand-alone and image-guided frameworks.
Yuan, Zhen; Zhang, Qizhi; Sobel, Eric; Jiang, Huabei
Ultrahigh speed endoscopic optical coherence tomography using micromotor imaging catheter and VCSEL technology
We developed a micromotor based miniature catheter with an outer diameter of 3.2 mm for ultrahigh speed endoscopic swept source optical coherence tomography (OCT) using a vertical cavity surface-emitting laser (VCSEL) at a 1 MHz axial scan rate. The micromotor can rotate a micro-prism at several hundred frames per second with less than 5 V drive voltage to provide fast and stable scanning, which is not sensitive to the bending of the catheter. The side-viewing probe can be pulled back to acqu...
Tsai, Tsung-han; Potsaid, Benjamin; Tao, Yuankai K.; Jayaraman, Vijaysekhar; Jiang, James; Heim, Peter J. S.; Kraus, Martin F.; Zhou, Chao; Hornegger, Joachim; Mashimo, Hiroshi; Cable, Alex E.; Fujimoto, James G.
High-resolution frequency-domain second-harmonic optical coherence tomography
We used continuum generated in an 8.5 cm long fiber by a femtosecond Yb fiber laser to improve threefold the axial resolution of frequency domain second-harmonic optical coherence tomography (SH-OCT) to 12 ?m. The acquisition time was shortened by more than 2 orders of magnitude compared to the time-domain SH-OCT. The system was applied to image biological tissue of fish scales, pig leg tendon, and rabbit eye sclera. Highly organized collagen fibrils can be visualized in the recorded images. Polarization dependence on the SH has been used to obtain polarization resolved images.
Su, Jianping; Tomov, Ivan V.; Jiang, Yi; Chen, Zhongping
A new algorithm for speckle reduction of optical coherence tomography images
In this study, we present a new algorithm based on an artificial neural network (ANN) for reducing speckle noise from optical coherence tomography (OCT) images. The noise is modeled for different parts of the image using Rayleigh distribution with a noise parameter, sigma, estimated by the ANN. This is then used along with a numerical method to solve the inverse Rayleigh function to reduce the noise in the image. The algorithm is tested successfully on OCT images of retina, demonstrating a significant increase in the signal-to-noise ratio (SNR) and the contrast of the processed images.
Avanaki, Mohammadreza R. N.; Marques, Manuel J.; Bradu, Adrian; Hojjatoleslami, Ali; Podoleanu, Adrian G.
Optical coherence tomography following percutaneous coronary intervention with Excimer laser coronary atherectomy
The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy.
Rawlins, John, E-mail: firstname.lastname@example.com; Talwar, Suneel; Green, Mark; O�Kane, Peter
Subgingival calculus imaging based on swept-source optical coherence tomography
We characterized and imaged dental calculus using swept-source optical coherence tomography (SS-OCT). The refractive indices of enamel, dentin, cementum, and calculus were measured as 1.625 +/- 0.024, 1.534 +/- 0.029, 1.570 +/- 0.021, and 2.097 +/- 0.094, respectively. Dental calculus leads strong scattering properties, and thus, the region can be identified from enamel with SS-OCT imaging. An extracted human tooth with calculus is covered with gingiva tissue as an in vitro sample for tomographic imaging.
Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Lu, Chih-Wei; Jiang, Cho-Pei; Chuang, Ching-Cheng; Wang, Chun-Yang; Sun, Chia-Wei
Spectral domain optical coherence tomography in mouse models of retinal degeneration
Purpose: Spectral domain optical coherence tomography (SD-OCT) allows cross-sectional visualization of retinal structures in vivo. Here, we report the efficacy of a commercially available SD-OCT device to study mouse models of retinal degeneration. Methods: C57BL/6 and BALB/c wild type mice and three different mouse models of hereditary retinal degeneration (Rho(-/-), rd1, RPE65(-/-)) were investigated using confocal scanning laser ophthalmoscopy (cSLO) for en face visualization and SD-OCT fo...
Huber, G.; Beck, S. C.; Grimm, C.; Sahaboglu-tekgoz, A.; Paquet-durand, F.; Wenzel, A.; Humphries, P.; Redmond, T. M.; Seeliger, M. W.; Fischer, D.
The early-stage diagnosis of albinic embryos by applying optical coherence tomography
Albinism is a kind of congenital disease of abnormal metabolism. Poecilia reticulata (guppy fish) is chosen as the model to study the development of albinic embryos as it is albinic, ovoviviparous and with short life period. This study proposed an imaging method for penetrative embryo investigation using optical coherence tomography. By imaging through guppy mother�s reproduction purse, we found the embryo�s eyes were the early-developed albinism features. As human�s ocular albinism typically appear at about four weeks old, it is the time to determine if an embryo will grow into an albino.
Yang, Bor-Wen; Wang, Shih-Yuan; Wang, Yu-Yen; Cai, Jyun-Jhang; Chang, Chung-Hao
High-resolution frequency-domain second-harmonic optical coherence tomography.
We used continuum generated in an 8.5 cm long fiber by a femtosecond Yb fiber laser to improve threefold the axial resolution of frequency domain second-harmonic optical coherence tomography (SH-OCT) to 12 microm. The acquisition time was shortened by more than 2 orders of magnitude compared to the time-domain SH-OCT. The system was applied to image biological tissue of fish scales, pig leg tendon, and rabbit eye sclera. Highly organized collagen fibrils can be visualized in the recorded images. Polarization dependence on the SH has been used to obtain polarization resolved images. PMID:17356620
Su, Jianping; Tomov, Ivan V; Jiang, Yi; Chen, Zhongping
The use of optical coherence tomography for morphological study of scaffolds
Aimed at possible widening of the optical coherence tomography (OCT) field of application, an attempt is made to use OCT in tissue engineering and cell transplantology as a tool for morphological studies of substrate materials by the example of scaffolds. By means of the traditional fibreoptical OCT scheme the images of inner structure of scaffolds are obtained, and simultaneously the spatial distribution of the intralipid flow velocity is reconstructed using the Doppler OCT. It is shown that combined use of traditional OCT and Doppler OCT schemes allows revealing the regions of the scaffold demonstrating optimal effect of shear stress, which is a key factor of cell growth.
Veksler, B A; Kuz' min, V L; Kobzev, E D; Meglinski, I V
Full-color skin imaging using RGB LED and floating lens in optical coherence tomography
The cosmetic industry has witnessed significant growth in recent years. Conventional hand-held skin cameras allow for 2D inspection of the skin surface. This paper proposes a new model for full-color 3D imaging of the skin tissue using fiber-based optical coherence tomography (OCT). Compared to laser or LD sources, RGB LED was found more suitable and thus chosen in the low-coherence interferometry due to its wider bandwidth. A floating objective lens was used to confocalize the R, G and B ima...
Yang, Bor-wen; Chen, Xin-chang
Spectral-domain optical coherence tomography use in macular diseases: a review.
The introduction of spectral-domain optical coherence tomography (SD-OCT) has improved the clinical value for assessment of the eyes with macular disease. This article reviews the advances of SD-OCT for the diagnostic of various macular diseases. These include vitreomacular traction syndrome, cystoid macular edema/diabetic macular edema, epiretinal membranes, full-thickness macular holes, lamellar holes, pseudoholes, microholes, and schisis from myopia. Besides offering new insights into the pathogenesis of macular abnormalities, SD-OCT is a valuable tool for monitoring macular disease. PMID:20453539
Wolf, Sebastian; Wolf-Schnurrbusch, Ute
Optical Tomography for Single- and Two-Mode Squeezed Chaotic Fields
Different from the previous methods of obtaining optical tomography of quantum states, in this paper we use the Radon transform between the single- (two-)mode Wigner operator and the pure-state density operator | q> f, g f, g f, g (| ?, ? 1, ? 2>) refer to the newly introduced intermediate coordinate-momentum (entangled) states. More interestingly, we find that the tomograms of squeezed chaotic fields and those of coherent states are related by a integration. Thus, we establish a new convenient approach of obtaining tomograms for quantum states.
Meng, Xiang-Guo; Xu, Ye-Jun
Imaging limbal and scleral vasculature using Swept Source Optical Coherence Tomography
We demonstrate an application of high-speed swept source optical coherence tomography for vessel visualization in the anterior segment of the human eye. The human corneo-scleral junction and sclera was imaged in vivo. Imaging was performed using a swept source OCT system operating at the 1050nm wavelength range and 100kHz A-scan rate. High imaging speed enables the generation of 3D depth-resolved vasculature maps. The vessel visualization method revealed a rich vascular system in the conjunct...
Grulkowski, Ireneusz; Liu, Jonathan J.; Baumann, Bernhard; Potsaid, Ben; Lu, Chen; Fujimoto, James G.
Ultra-high sensitive and high resolution optical coherence tomography using a laser induced electromagnetic dipole
Utilizing an optical coherence tomography measurement, we have developed a technique that actively uses a dielectric response due to an induced dipole moment caused by a mode-locked pulsed laser light source. Irradiated laser light in the material induces a photo-induced electric dipole resulting in a refractive index change for its strong electric field. Using this technique, we obtained a highly sensitive fundus retina tomogram of a human eye in vivo with a resolution of 1.3 ?m by single scanning for 20 ms using 8 fs mode-locked pulse laser light with a 350 nm spread spectrum.
Kuroda, Hiroto; Baba, Motoyoshi; Suzuki, Masayuki; Yoneya, Shin
Spectral domain optical coherence tomography features of multiple subfoveal retinal pigment epithelial tears after intravitreal bevacizumab
Full Text Available Retinal pigment epithelial (RPE tear has been described to occur spontaneously, after laser photocoagulation and in recent times, after intravitreal injection of anti-vascular endothelial growth factor (VEGF agents. In the latter case, the rapid contraction of the choroidal vascular membrane underneath a serous RPE detachment is believed to be the underlying cause. Preservation of good visual acuity after the occurrence of RPE tear with continued use of intravitreal VEGF agents has been reported. In this case report, we describe the occurrence of multiple RPE tears with the use of intravitreal bevacizumab and also correlate the preservation of visual acuity with features seen on spectral domain optical coherence tomography.
Chalam Kakarla
Feasibility of glucose monitoring based on Brownian dynamics in time-domain optical coherence tomography
Our purpose is to investigate the feasibility of Brownian motion in time-domain optical coherence tomography (OCT) incorporated with wavelet power spectrum to monitor glucose concentration in Intralipid solution. The results show that the standard deviation (SD) of frequency in the superficial layer of single scattering region, linearly proportional to Brownian diffusion coefficient, is independent of the depth. Our preliminary results demonstrate that average SD of frequency in the single scattering region is inversely proportional to the glucose concentration in Intralipid solution, since the Brownian diffusion coefficient is a function of concentration. Thus the average SD of frequency in OCT signal is capable of differentiating the glucose concentration.
Li, Z. F.; Li, H.; Li, J. J.; Lin, X. N.
Spectral-domain optical coherence tomography imaging of macula-off rhegmatogenous retinal detachment
Full Text Available Jayanth Sridhar, Harry W Flynn Jr Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, FL, USA Abstract: The timing of repair and the utility of spectral-domain optical coherence tomography (SD-OCT for macula-off retinal detachment remains a controversial issue. Four patients who presented with macula-off retinal detachment underwent repair at various time points after symptom onset. Postoperative SD-OCT of the macula demonstrated correlation with final visual acuity. Keywords: SD-OCT, vitrectomy, scleral buckle
Sridhar J
Optical coherence tomography predicts visual outcome in macula-involving rhegmatogenous retinal detachment
Full Text Available Minhee Cho1,*, Matthew T Witmer1,*, Guilleherme Favarone2, RV Paul Chan1, Donald J D'Amico1, Szil�rd Kiss11Weill Cornell Medical College, Department of Ophthalmology, New York, NY, USA; 2Hospital do Olho Rio Preto, Department of Retina and Vitreous, S�o Jos� do Rio Preto, Brazil *These authors contributed equally to this workPurpose: Visual recovery after rhegmatogenous retinal detachment (RRD repair depends upon various anatomical factors. We investigated spectral-domain optical coherence tomography (SD-OCT abnormalities, pre- and postoperatively, in patients with nontraumatic RRD and correlated these findings with visual outcome.Methods: The medical records of all patients presenting to Weill Cornell Medical College with nontraumatic macula-involving RRD from August 2010 to September 2011 were retrospectively reviewed in this single-center, consecutive case series. All patients underwent pre- and postoperative visual acuity (VA testing, slit-lamp biomicroscopy, and dilated fundus examination. Spectral domain optical coherence tomography was obtained preoperatively in twelve patients and postoperatively in ten patients.Results: Twelve patients (12 eyes were included in the final analysis. Preoperative optical coherence tomography revealed that the inner segment/outer segment (IS/OS junction was disrupted in 10/12 eyes (83%, the external limiting membrane (ELM was disrupted in 9/12 (75% eyes, cystoid macular edema (CME was present in 10/12 (83% eyes, an epiretinal membrane (ERM was present in 2/12 eyes (17% and outer retinal corrugation was present in 7/12 (58% eyes. In postoperative imaging of 10 eyes, the IS/OS junction was disrupted in 4/10 (40%, the ELM was disrupted in 3/10 (30% eyes, CME was present in 2/10 (20%, and an ERM in 1/10 (10%. All retinas were attached postoperatively. Outer retinal corrugation was the most predictive of worse preoperative (P = 0.0016 and 1-month postoperative visual acuity (P = 0.05.Conclusion: Preoperative SD-OCT demonstrating outer retinal corrugation in macula involving RRD predicts poor visual acuity outcome in nontraumatic RRD. Such findings may have implications for the urgency for these eyes to undergo surgical repair.Keywords: macula-involving, optical coherence tomography, outer retinal corrugation, retinal detachment
Cho M
Simultaneous reconstruction of absorbed optical energy density and speed of sound distributions in photoacoustic computed tomography
An important and interesting question in photoacoustic computed tomography (PACT) is whether the absorbed optical energy density distribution, A(r), and the speed of sound distribution, c(r), can both be accurately determined from the measured photoacoustic data alone. However, in many cases c(r) is unknown or cannot be accurately estimated. Therefore, it would be practically beneficial if A(r) and c(r) can be jointly reconstructed from the measurements. In this work, we propose a reconstruction approach to the joint reconstruction of both properties in PACT.
Huang, Chao; Wang, Kun; Schoonover, Robert W.; Wang, Lihong V.; Anastasio, Mark A.
An elegant technique for ex vivo imaging in experimental research�??Optical coherence tomography (OCT)
Optical coherence tomography (OCT) is an elegant technology for imaging of tissues and organs and has been established for clinical use for around a decade. Thus, it is used in vivo but can also serve as a valuable ex vivo imaging tool in experimental research. Here, a brief overview is given with a focus on an ex vivo application of OCT. Image and video examples of freshly obtained murine lungs are included. The main advantage of OCT for ex vivo analysis is the non-contact, non-invasive, and non-destructive fast acquisition of a three-dimensional data set with micrometer-resolution.
Tschernig, T.; Thrane, Lars
Gold nanorods tailored as tracers for sentinel lymph node biopsy imaged by photothermal optical coherence tomography
Gold nanorods (GNRs) have been demonstrated as a scattering imaging agent or therapeutic agent. Because of their narrow window, biocompatibility, and uniform small size for blood circulation, GNRs are well suited to serve as imaging contrast agents. Especially, strong phothothermal (PT) effect is attractive for diagnostic (e.g. sentinel lymph node biopsy) or therapeutic (e.g. PT therapy) purposes. In this paper, we demonstrate GNRs as multipurpose agents with PT-optical coherence tomography (OCT) for imaging sentinel lymph node. The results show that GNRs are promising for imaging contrast enhancement for visualizing the detailed functions of SLN.
Jung, Yeongri; Wang, Ruikang K.
The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy
Optical coherence tomography following percutaneous coronary intervention with Excimer laser coronary atherectomy.
The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy. PMID:24238883
Rawlins, John; Talwar, Suneel; Green, Mark; O'Kane, Peter
Tomografia de coer�ncia �ptica broncosc�pica / Optical coherence tomography in conjunction with bronchoscopy
Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Avaliar a viabilidade e o potencial do uso da tomografia de coer�ncia �ptica em conjunto com um broncosc�pio convencional na avalia��o das vias a�reas. M�TODOS: Estudo piloto baseado em um modelo experimental ex vivo com tr�s animais: um coelho adulto da ra�a Nova Zel�ndia e dois su�nos da [...] ra�a Landrace. Um cateter de imagem de tomografia de coer�ncia �ptica foi inserido no canal de trabalho de um broncosc�pio flex�vel para alcan�armos a traqueia distal dos animais. As imagens foram obtidas sistematicamente em toda a traqueia ao longo das paredes, partindo da por��o distal para a proximal. RESULTADOS: O cateter de imagem se adaptou com facilidade ao canal de trabalho do broncosc�pio. Imagens em alta resolu��o de cortes transversais da traqueia foram obtidas em tempo real, sendo delineadas microestruturas, tais como epit�lio, submucosa, cartilagem e camada advent�cia nas paredes anteriores e laterais da traqueia. As camadas correspondentes do epit�lio, mucosa e cartilagens foram claramente diferenciadas. Na parede posterior, foi poss�vel identificar mucosa, submucosa e musculatura traqueal. CONCLUS�ES: O uso de tom�grafo de coer�ncia �ptica em conjunto com um broncosc�pio flex�vel � vi�vel. A tomografia de coer�ncia �ptica produz imagens de alta resolu��o que permitem visualizar a microanatomia da traqueia, inclusive estruturas que normalmente s�o visualizadas somente na histologia convencional. Abstract in english OBJECTIVE: To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways. METHODS: This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rab [...] bit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion. RESULTS: The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall. CONCLUSIONS: It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high-resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology.
Rodrigues, Ascedio Jos�; Takimura, Celso Kiyochi; Lemos Neto, Pedro Alves; Figueiredo, Viviane Rossi.
Depth-resolved blood oxygen saturation measurement by dual-wavelength photothermal (DWP) optical coherence tomography
Non-invasive depth-resolved measurement of hemoglobin oxygen saturation (SaO2) levels in discrete blood vessels may have implications for diagnosis and treatment of various pathologies. We introduce a novel Dual-Wavelength Photothermal (DWP) Optical Coherence Tomography (OCT) for non-invasive depth-resolved measurement of SaO2 levels in a blood vessel phantom. DWP OCT SaO2 is linearly correlated with blood-gas SaO2 measurements. We demonstrate 6.3% precision in SaO2 levels measured a phantom ...
Kuranov, Roman V.; Qiu, Jinze; Mcelroy, Austin B.; Estrada, Arnold; Salvaggio, Anthony; Kiel, Jeffrey; Dunn, Andrew K.; Duong, Timothy Q.; Milner, Thomas E.
Simultaneous dual wavelength eye-tracked ultrahigh resolution retinal and choroidal optical coherence tomography
We demonstrate an optical coherence tomography device that simultaneously combines different novel ultrabroad bandwidth light sources centered in the 800 and 1060 nm regions, operating at 66 kHz depth scan rate, and a confocal laser scanning ophthalmoscope-based eye tracker to permit motion-artifact-free, ultrahigh resolution and high contrast retinal and choroidal imaging. The two wavelengths of the device provide the complementary information needed for diagnosis of subtle retinal changes, while also increasing visibility of deeper-lying layers to image pathologies that include opaque media in the anterior eye segment or eyes with increased choroidal thickness.
Müller, André; Jensen, Ole Bjarlin
Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit
We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU) computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time at 120 fps for 1,024 pixels � 512 lateral A-scans. The computing time for the Doppler information was dependent on the size of the moving average window, but with a window size of 32 pixels the ODT...
Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility.
Optical coherence tomography (OCT) has the combined advantage of high temporal (�sec) and spatial (<10�m) resolution. These features make it an attractive tool to study the dynamic relationship between neural activity and the surrounding blood vessels in the spinal cord, a topic that is poorly understood. Here we present work that aims to optimize an in vivo OCT imaging model of the rodent spinal cord. In this study we image the microvascular networks of both rats and mice using speckle variance OCT. This is the first report of depth resolved imaging of the in vivo spinal cord using an entirely endogenous contrast mechanism. PMID:22567584
Cadotte, David W; Mariampillai, Adrian; Cadotte, Adam; Lee, Kenneth K C; Kiehl, Tim-Rasmus; Wilson, Brian C; Fehlings, Michael G; Yang, Victor X D
Imaging the eye fundus with real-time en-face spectral domain optical coherence tomography
Real-time display of processed en-face spectral domain optical coherence tomography (SD-OCT) images is important for diagnosis. However, due to many steps of data processing requirements, such as Fast Fourier transformation (FFT), data re-sampling, spectral shaping, apodization, zero padding, followed by software cut of the 3D volume acquired to produce an en-face slice, conventional high-speed SD-OCT cannot render an en-face OCT image in real time. Recently we demonstrated a Master/Slave (MS...
Optical coherence tomography findings of pigmented fundus lesions in familial adenomatous polyposis.
The pigmented fundus lesions associated with familial adenomatous polyposis (FAP) often resemble those characteristic of congenital hypertrophy of the retinal pigment epithelium (CHRPE). However, some fundus lesions in FAP resemble hamartomatous lesions of the retinal pigment epithelium (RPE). Intraretinal extension of the RPE is a feature not seen in CHPRE lesions that may be unique to some of the pigmented lesions of FAP. The authors report the spectral-domain optical coherence tomography findings of the pigmented ocular lesions associated with FAP in a 10-year-old boy. PMID:24266367
Tzu, Jonathan H; Cavuoto, Kara M; Villegas, Victor M; Dubovy, Sander R; Capo, Hilda
High-speed fiber based polarization-sensitive optical coherence tomography of in vivo human skin.
A high-speed single-mode fiber-based polarization-sensitive optical coherence tomography (PS OCT) system was developed. With a polarization modulator, Stokes parameters of reflected flight for four input polarization states are measured as a function of depth. A phase modulator in the reference arm of a Michelson interferometer permits independent control of the axial scan rate and carrier frequency. In vivo PS OCT images of human skin are presented, showing subsurface structures that are not discernible in conventional OCT images. A phase retardation image in tissue is calculated based on the reflected Stokes parameters of the four input polarization states. PMID:18066215
Saxer, C E; de Boer, J F; Park, B H; Zhao, Y; Chen, Z; Nelson, J S
Imaging of non-parabolic velocity profiles in converging flow with optical coherence tomography
The optical coherence tomography method was explored for two-dimensional flow mapping of a highly scattering fluid in flow with complex geometry. Converging flow (capillary entry) with 4:1 constriction was used for demonstration of non-invasive and remote methods of mapping varying velocity profiles. Downstream of the geometry was scanned with ? 10 x 10 x 10 ?m3 spatial resolution and structural imaging of the lumen and images of one particular velocity were acquired. Stable concave, blunted and parabolic profiles are obtained at different distances of the inlet length. Application of the technique for the blood circulation is also discussed
In vivo vibrometry inside the apex of the mouse cochlea using spectral domain optical coherence tomography.
Sound transduction within the auditory portion of the inner ear, the cochlea, is a complex nonlinear process. The study of cochlear mechanics in large rodents has provided important insights into cochlear function. However, technological and experimental limitations have restricted studies in mice due to their smaller cochlea. These challenges are important to overcome because of the wide variety of transgenic mouse strains with hearing loss mutations that are available for study. To accomplish this goal, we used spectral domain optical coherence tomography to visualize and measure sound-induced vibrations of intracochlear tissues. We present, to our knowledge, the first vibration measurements from the apex of an unopened mouse cochlea. PMID:23411442
Gao, Simon S; Raphael, Patrick D; Wang, Rosalie; Park, Jesung; Xia, Anping; Applegate, Brian E; Oghalai, John S
Optical computed tomography of radiochromic gels for accurate three-dimensional dosimetry
In this thesis, three-dimensional (3-D) radiochromic Ferrous Xylenol-orange (FX) and Leuco Crystal Violet (LCV) micelles gels were imaged by laser and cone-beam (Vista(TM