inside blood vessels. This is commonly used to measure the size of blood vessels and to measure the internal diameter of the blood vessel. For example, this can be used in a coronary angiogram to assess the narrowing of the coronary artery. If the catheter is retraced in a controlled manner, then an internal map can be generated to see the contour of the vessel and its branches. Modes The various modes listed below essentially describe how the ultrasound crystals are used to obtain information. These modes are common to all types of echocardiography. A-mode Amplitude mode is not a mode used in modern echocardiography. B-mode / 2D Brightness mode is often synonymous with "2D" and is very commonly used in echocardiography. M-mode Motion mode is infrequently used in modern echocardiography. It has specific uses and has the benefit of very high temporal fidelity (e.g., measuring LV size at end diastole). Strain rate imaging (deformation echocardiography) Strain rate imaging is an ultrasound method for imaging regional differences in contraction (dyssynergy) in for instance ischemic heart disease or dyssynchrony due to Bundle branch block. Strain rate imaging measures either regional systolic deformation (strain) or the rate of regional deformation (strain rate). The methods used are either tissue Doppler or Speckle tracking echocardiography. Three-dimensional echocardiography Three-dimensional echocardiography (also known as four-dimensional echocardiography when the picture is moving) is now possible, using a matrix array ultrasound probe and an appropriate processing system. It enables detailed anatomical assessment of cardiac pathology, particularly valvular defects, and cardiomyopathies. The ability to slice the virtual heart in infinite planes in an anatomically appropriate manner and to reconstruct three-dimensional images of anatomic structures make it unique for the understanding of the congenitally malformed heart. Real-time three-dimensional echocardiography can be used to guide the location of bioptomes during right ventricular endomyocardial biopsies, placement of catheter-delivered valvular devices, and in many other intraoperative assessments. Three-dimensional echocardiography technology may feature anatomical intelligence, or the use of organ-modeling technology, to automatically identify anatomy based on generic models. All generic models refer to a dataset of anatomical information that uniquely adapts to variability in patient anatomy to perform specific tasks. Built on feature recognition and segmentation algorithms, this technology can provide patient-specific three-dimensional modeling of the heart and other aspects of the anatomy, including the brain, lungs, liver, kidneys, rib cage, and vertebral column. Contrast echocardiography Contrast echocardiography or contrast-enhanced ultrasound is the