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NyoezBq14vE | but this gives you the basic concept at the simplest level so for photoacoustic CT the first thing we do is to expand the laser beam very different from a common use of laser where you want to use a very high intensity to drill a piece of metal for example so when we talk about laser you say well that would be dangerous you know this is a laser beam here I want to have high | 1,639 | 1,664 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1639s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | collimation this is not very high power so the first thing we have to guarantee is safety what we do is to broaden the laser beam make sure the light intensity is within the safety limit so there's this institute called ANSI that regulates the safety of laser use if you stay within the safely safety element you're very very safe light will be scattered around so if you want to image | 1,664 | 1,697 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1664s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | deep you have to tolerate light scattering we actually allow photons to scatter so you can penetrate multiple millimeters even multiple centimeters in biological tissue when light is absorbed it generates some heating we use very short laser pulses nanosecond right one nanosecond is a 1 1 billionth of a second right very very short laser pulses so this heating is very very rapid and we | 1,697 | 1,728 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1697s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | don't need a lot of heating milli degrees right so one one thousandth of a degree would be adequate that will give you a detectable signal already so if you generate hundred hundreds of milli henries of million agrees then you have a very good signal to work with that allows you to form a bright image so this transiting allows us to generate ultrasonic emission is going to generate | 1,728 | 1,753 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1728s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | Christic wave through the photo acoustic effect okay so this is the bells effect and because of the acoustic transparency we can detect all the acoustic signals and form a very sharp image outside however the contrast comes from optical absorption so we're combining optical contrast without drisana krez Ellucian these one common question is why don't we use ultrasound tomography why do you | 1,753 | 1,782 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1753s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | have to use photo acoustics so you notice on tomography as you know you actually fire ultrasound pulse into tissue then listen to the echoes right so medical ultrasound imaging originated from sauna of sonar right so after the Second World War scientists and physicians started to borrow that technique in a pointer for a human imaging so what ultrasound imaging | 1,782 | 1,809 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1782s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | does not provide is the optical contrast we want to have the optical mechanism as the contrast so we have access to molecular level information for example using light later I'm going to show you we can see the color differences of the two forms of blood oxygenated blood and deoxygenated blood red versus blue our veins you know look blue right the arteries will look red so ultrasound | 1,809 | 1,837 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1809s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | will not be able to tell the difference that's just one example this is the first set of functional photoacoustic images it's also the first set of in vivo images acquired using photo acoustic CT this was reported in 2003 by our lab and we can see actually brain activation if he we go one side of the whiskers of assam animal and the contralateral side of the brain would be hemodynamically | 1,837 | 1,868 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1837s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | activated so the blood flow will change and we can detect that change to show the brain activation on one side and those images were acquired now evasively so this work really started the growth of our field you know if you look at after 2003 our field really doubled roughly every three years in size after 2010 the conference on this topic became the largest in photonics West which is a | 1,868 | 1,901 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1868s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | twenty thousand attendee gathering right so this has surpassed a lot of the competing technologies or you know peer technologies a natural question is why is this technology so exciting well this is probably the only technology that allows us to image from organelles all the way to organs in vivo and we use the same contrast right so we use the optic absorption as the contrast mechanism so | 1,901 | 1,934 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1901s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | I'm plotting different implementations of this technology right we actually have far more than that can pot here but this says this is a highly scalable technology we can image at very much microscopic level but we can also scale to the macroscopic level this type of multi scale imaging can be very very important because in current medical practice or biomedical practice for | 1,934 | 1,962 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1934s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | cells and below we use optical microscopy so we're acquiring optical contrast but for tissues and above we switched to now optics we're gonna use MRI ultrasound x-ray CT what have you so we're talking about two different contrast mechanisms mechanisms preventing us from correlating images across all the lens skills as we know to understand about the problem we have to have a multiscale | 1,962 | 1,990 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1962s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | understanding you have to correlate information across the learn skills so photo tomography can potentially allows us to do so by enabling multi scale biological research and enabling translation of microscopic discovery to macroscopic clinical practice at least accelerate the pace of such translation so for the 2003 work we actually use a single element transducer that took like | 1,990 | 2,027 | https://www.youtube.com/watch?v=NyoezBq14vE&t=1990s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | 20 minutes to get a 2d image now we have ultrasone arrays with 512 elements within 2 seconds so we can get a 2d image in fact now in our lab we're building a system that allows us to get an image within one millisecond so the technology is really getting faster and faster in terms of data acquisition so we can image the whole body of its Manimal right without without injecting | 2,027 | 2,055 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2027s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | any contrast agents we can see the internal organs we've got 10 defined boundaries detect tumors detect functions the farmers are very interested in in this type of technology because what is the alternative to see this type of contrast they have to use x-ray CT the radiation dose is a big problem to monitor the same animal for development of a new drug you have to monitor the animal | 2,055 | 2,081 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2055s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | multiple time points over a time course of a couple months at least so the radiation dose can kill the animal and it doesn't give you enough information as well because x-rays sometimes does not provide enough information right you have to have the functional information to make your to test the efficacy of the drug further acoustic tomography is simultaneously analogous to MRI in | 2,081 | 2,113 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2081s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | pet so this is one example on this site we can see the hemodynamic contrast right so this is the concentration of hemoglobin we detect the brain again in response to electric stimulation of the pause of the animal on one side you can see the counter lateral side of the brain activate so on this side we're showing why this is analogous to PET imaging so we're using a glucose analog | 2,113 | 2,144 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2113s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | that mimics glucose so when there's glucose uptake you can see stronger signals right this is very much like PET imaging so this can be potentially very powerful in the future as well because photo acoustics can serve as a backbone to connect with other standard modalities like MRI and PET we're trying to push bring image into the ultimate level human brain imaging this is extremely | 2,144 | 2,175 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2144s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | challenging problem because human skull is a lot thicker than animal skull so that causes problems because the skull has a different speed of sound and soft tissue so this is like a photograph of the x-ray CT image X X we go a tall skull and this is a photograph and we put this k9 brain inside this skull which are the image using photo acoustic tomography actually some of the | 2,175 | 2,205 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2175s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | colleagues predicted this will not be possible because the skull is so thick we got very very encouraging data so we got a image that shows certain structures which match the structures in the photograph very well the next big step is to push this to in vivo imaging of human brain unlike x-ray CT which always works in transmission mode because x-ray doesn't scatter much further acoustic waves | 2,205 | 2,240 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2205s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | propagate essentially in all directions so that means we're very flexible in terms of actually implementation I just talked about the circular geometry for detection but we can also do it using a linear geometry so this is a hand hold ultrasound probe that you might have seen the hospital we have like hundreds of ultrasound detectors along this probe we use optical fibers optical fiber | 2,240 | 2,269 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2240s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | bundles to deliver light with a single laser shot we can illuminate a volume below this linear probe it allows us to form a two-dimensional image so all the data will be acquired within say 100 microseconds so your boy motion artifacts when you acquire this type of images and you can see this is actually a standard ultrasound machine we worked in cooperation with Philips to modify this | 2,269 | 2,297 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2269s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | clinic ultrasound system for concurrent photoacoustic imaging yogic dual contrasts for the acoustic contrast in ultrasonic contrast so this system works around this point allows you to penetrate multiple centimeters and get hundreds of microns resolution this is a one example where we can see a tiny absorber buried at a depth of five centimeters right this was not possible | 2,297 | 2,329 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2297s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | using standard optical imaging right at this type of resolution in fact this is a form of reporter gene imaging or a form of molecular imaging again three colleagues receive the Nobel Prize in 2008 for their discovery of force and proteins you might have heard of you know this is a huge discovery that allows us to follow gene expressions but it's all fluorescence based by using | 2,329 | 2,360 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2329s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | standard optical imaging you cannot penetrate these so all of the applications are limited to cells or animals at a very shallow depth now we're talking about multiple centimeters of penetration for this type of imaging so this is going to extend the capability of fluorescent proteins and some of the derivatives this technology is being tested at Washington University | 2,360 | 2,392 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2360s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | for a human studies for human applications and this is one example where a breast tumor was imaged using standard ultrasound imaging and photoacoustic imaging we can see the CM tumor using a very safe light dose the laser intensity is one-half of the safety limit and a safety light safety limit is less than one-tenth of the dams threshold so this is extremely safe level light those we're | 2,392 | 2,424 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2392s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | also targeting something that might have a more immediate application which is breast cancer staging you might have heard that the standard breast cancer staging is invasive you have to surgically remove the first draining node or the central nerve node what we want to do is to inject organic dye near the tumor it's gonna flow toward a central enough node then we use the | 2,424 | 2,450 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2424s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | photo acoustics to detect us in the lymph node and use a needle which is guided by the photo acoustic technology to take cells out of the simple nerves node do you test if there's any presence of cancer cells so once this is a proven we can convert the surgical surgical procedure into a needle biopsy procedure this is some of the initial test results in humans you can see the central nodes | 2,450 | 2,477 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2450s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | note we can see the needle here at as well in there another clinical problem is to monitor the brain oxygen consumption in the surgery you want to do it in the war but there's no non-invasive technique allows us to do that well so the current technique is invasive you have to insert into the carotid artery and jugular vein some sensors to detect the oxygen content so | 2,477 | 2,507 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2477s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | can we do this now you massively we can use photo cosec tomography to quantify the oxygen saturation we use so2 to represent the oxygen saturation level at both the caudate artery in the jugular vein and you'll see that they have different values the difference in so2 tells you how much oxygen has been extracted by the brain so this is an indicator that tells you how well our | 2,507 | 2,536 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2507s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | brain is consuming the oxygen if this difference is too small that means the patient is not consuming enough oxygen are you going to do something about it otherwise the patient might wake up from the surgery bring that so we've tested seven healthy volunteers that reach so2 is very similar to the expected range so this is very good news for us as a initial test the next | 2,536 | 2,564 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2536s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | natural step is to move this into the war to work on real patients let me move on to the microscopy domain unlike the photoacoustic CT you will have to use math to form an image you know you have hundreds of sensors that Christic sensors you get all the signals then you send the data to a computer use your algorithm to form a image someone like x-ray CT image reconstruction but it's | 2,564 | 2,596 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2564s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | actually more sophisticated because it deals with extra dimension so here we're gonna use acoustical lens very much too like lenses like I'm wearing a pair of lenses and everybody has a pair of lenses Eve even if you don't wear glasses right our eyeballs actually have lenses inside as well these are biologically made so here we're gonna use the acoustic version of | 2,596 | 2,622 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2596s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | lenses to firmly image it directly let's just assume there's a target you know a piece of tissue we want an image we fire a light pulse to illuminate the tissue to generate photo acoustic waves and then we use this focused ultrasound transducer to receive the signals and you're gonna get a time trace like this so this is your time axis you get a voltage like this you'll see a spike | 2,622 | 2,651 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2622s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | corresponding to where the target is so if this guide is deeper then this spike is gonna appear later if you have multiple absorbers or targets you'll see multiple spikes because we know the speed of sound in tissue we can convert this time of arrival into depth so this time trace is essentially a one dimensional image we call that a scan right or 1d image if we scan the system | 2,651 | 2,681 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2651s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | across the Tish we got a 2d image you would call that be Skinner right now if you're Astros game on a tissue surface you got a 3d image so that's the basic concept and this is the detail now maybe I should skip this is this photograph shows the first 3d photo microscope which we published in 2005 so this is used to implement the idea I just described right so we focus light into tissue | 2,681 | 2,716 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2681s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | right to penetrate deep beyond like a millimeter which is the limit how far how well we can focus right beyond a millimeter you can't really focus so well and so we use this what's called a dark field we use a done' beam on a surface to minimize the surface interference and then the ultrasound transducer is comfo wholly located you just want to maximize your signal | 2,716 | 2,743 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2716s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | strength with a single laser shot you get a 1d image in the depths duration so this head is raster scan XY scan in its water tray to get a 3d image so this is the map rates around this point it penetrates three millimeters we can scale to a few more millimeters if we won't add expensive resolution everybody you can get tens of microns resolution so the resolution is getting better this | 2,743 | 2,774 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2743s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | is an image of our own skin in this area of the palm there you can see blood vessels without injecting any contrast agents if you want to get the same type of images use x-ray you have to inject iodine base contrast or some other heavy metal phase contrast even then you'll miss some of the smaller vessels because x-ray does not give you enough contrast for vessel imaging so we all know the | 2,774 | 2,800 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2774s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | importance of blood vessels this is a depth result or be scanned image showing you some of the standard skin structures now we're working with our dermatology department you apply this technology for melanoma imaging we've also miniaturized the probe so we can use this technology in the GI tract all right so you have to make the device tiny in order to be inserted into the | 2,800 | 2,834 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2800s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | standard endoscope so unlike standard endoscopy like colonoscopy for example which only detects the surface of the lumen or the colon right so here we want to image beyond the surface these standard colonoscopy or upper GI endoscopy will miss anything beyond the surface we want to see deeper right seven millimeters is sufficiently deep in terms of the GI wall right so that | 2,834 | 2,869 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2834s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | allows us to see the deeper structures by providing both photo acoustic and ultrasonic contrast mechanisms so this technology has been licensed to a large company for human translational commercialization I'll skip some of the details on the engineering side and this is by the way this is the first photo Costa endoscope we can also implement a photo acoustic microscopy at even finer | 2,869 | 2,903 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2869s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | resolution so if we sacrifice the penetration now we're back within one millimeter penetration these we do want to cover the very top layer of the of the thickness so you can focus light more tightly that allows you to get finer resolution and you do have to somehow collect the ultrasound wave so we have to engineer this transducer or beam combine or what we call light some | 2,903 | 2,929 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2903s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | combiner that allows us to combine the light optical axis and acoustic axis make them coaxial right so with a single laser shot you get an image 1d image and then you can raster scan to get a 3d image so this technology works around this point right so your penetration is about one point two millimeters but you're getting a single-digit micron resolution so this is one example where you can | 2,929 | 2,959 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2929s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | monitor the same animal over time so this is angiogenesis meaning new growth of blood vessels right so we can monitor this process because angiogenesis is a hallmark of cancer cancer cannot grow without growing more blood vessels so it's a very important process of cancer growth and of course this is just the one side of the story the flip side of the story is we can potentially we're | 2,959 | 2,987 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2959s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | actually doing that we're using the same technology to monitor drug the targets angiogenesis so we can use this as a therapeutic technology now therapeutic you use the anti-angiogenic drug to treat into genesis and we can monitor the efficacy of the drug this is another example we can see essentially every single blood vessel in the skin including the smallest capillaries you | 2,987 | 3,021 | https://www.youtube.com/watch?v=NyoezBq14vE&t=2987s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | can see here these are capillary pads you know the lines are single capillaries that are actually single of ourselves so we're looking at single cell lab already using this technology without injecting any contrast agents this is all what we coin dodged in this contrast we can also detect the color you know because our C and D arcy hemoglobin molecules have different | 3,021 | 3,046 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3021s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | colors right so we can quantify the concentrations of both forms from which we can compute their oxygen saturation of hemoglobin right this is a very important parameter and we can detect arteries and veins by looking at the colors and this is actually coming out of our finger cuticle so we can image a human capillary loops and watch the color of the blood vessels and that | 3,046 | 3,075 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3046s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | tells you where oxygen is released the most it turned out at the tip of the capillary loop seems to release most of the oxygen right so this is very interesting physiology in one day we can potentially use this to monitor some of the diseases involved in in human capillary level even some of the diabetic applications we're trying to push this photoacoustic oximetry to the | 3,075 | 3,107 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3075s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | ultimate level right this is the device working at 1 Hertz just for demonstration purposes this is 20 Hertz and we actually work at 200 Hertz at this rate we can see single red blood cells traveling right so you can resolve single red blood cells in real time in vivo and watch how red blood cells bifurcate at this Junction we can also look at the color of each red blood cell | 3,107 | 3,138 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3107s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | and look at how oxygen is released from red blood cells as we know red blood cells are oxygen carriers so this is the ultimate level oximetry it allows us to study some of the fundamental biology related to oxygen delivery and of course this is very much relevant to to cancer metabolism now this is very recent the data is unpublished as we know cancer primary tumor will not normally kill | 3,138 | 3,174 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3138s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | patients is the metastasis that kills the patients so when the primary tumor somehow transported to a distant site that grows a new tumor and a grow to grow everywhere that kills the patient so CTC or circulating tumor cells are very important because this is one mechanism where cancer cells spread now we're able to monitor you'll see these flashes of white ash these are | 3,174 | 3,205 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3174s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | circulating tumor cells if we can man identify them in the bloodstream right you can do multiple things to stop the metastasis right you could well you can imagine that potentially you can simply zap there's circulating tumor cells using a higher energy laser pulse that would be a Wang approach there are certain other pharmaceutical approaches you can think of I talked about | 3,205 | 3,239 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3205s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | histology right so how can we make standard histology now invasive in vivo and we can actually detect the cell nuclei directly by using photo cosa microscopy we get an image that looks almost like standard HD staining histology so this is the standard histology this is the same piece of tissue that we acquired using our native contrast we use the optical contrast so | 3,239 | 3,267 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3239s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | we can potentially move this into the o.r and find out brain tumor margin for example right so that can potentially improve patient survival we also try to beat that wavelength limit for resolution so you can see here this is the stander microscopy at a very fine resolution already but we improve that further to a resolution of 19 an au meters so this is sometimes called super | 3,267 | 3,298 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3267s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | resolution imaging we break through this wave lens however to limit for resolution now we're detecting mitochondrion we can see some of the internal structures of a single metal counterion so now we're talking about this regime of resolution so so far I've demonstrated the scalability of photoacoustic tomography has applications in animals cells all the way to humans but we're also working on | 3,298 | 3,331 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3298s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | time reversal because eventually wanna beat the penetration limit the photo acoustic tomography go even beyond what's available right now so time reversal is possibly one solution this is a very very interesting concept you know the we are actually inspired by astronomy the astronomers started something very similar because they want to observe the stars clearly | 3,331 | 3,356 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3331s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | but our atmosphere is going to distort the wave coming onto the earth so that allows actually pours the images what they do is the fire a laser beam to generate some sparks the sparks in the sky will serve as a guide star there is its artificial Chi star it allows us to correct the wavefront distortion as a result you can form a sharp image like this so it's very striking difference | 3,356 | 3,388 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3356s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | all right can we do the same thing in biological tissue right so we don't have first of all we don't have a guys there how do we solve that problem in biological tissue well let me illustrate the time reversal concept using this cartoon let's say we have a tiger this there's a bottle of liquid right that's gonna cause way front distortion so if you have plane wave way from very nice | 3,388 | 3,417 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3388s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | way from on this side as a propagates through this bottle it becomes this wavy way from right this wave wave wave away from if it's reflected by this standard mirror like the mirror you use every morning it's gonna cause basically return its way from it'll stay wavy and when you go through this bottle again it'll become even more wavy alright so the conventional mirror is not gonna | 3,417 | 3,446 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3417s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | give you anything that's reasonable it's not gonna give you a sharp image in fact you know by going through the bottle twice you get twice distorted you get an image that looks like a distorted tiger but if you use this special mirror something called the face conjugating mirror that's going to return the way frown in assert in the same direction right so you notice here this way from | 3,446 | 3,473 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3446s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | curvatures are complementary to the from here right but this phase conjugate mirror is gonna return away from a in the same direction this is almost like a time reversal right the concept is like a time reversal you record some scene right if the person walks forward you play it backward the person is gonna walk backward so we want a wave we want an optical waves to walk backwards right | 3,473 | 3,502 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3473s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | so that's why the phase can't you mirror does right when you go through the bottle the wavefront distortion is gonna be canceled through this bottle you get a very nice way from now you can see a very sharp image so that's the power of time reversal how do we implement the same concept in biological tissue we knew the guy star first of all to begin with which is really hard to do in | 3,502 | 3,527 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3502s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | tissue in the early days our field actually embedded some molecules into tissue that provides it guys that are the trouble is that's invasive you have to poke the tissue to you eject some dye or floor force and it's also not very flexible because once you have that molecule in the location that's fixed you can only focus light to that position so what we do here is to focus | 3,527 | 3,552 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3527s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | ultrasound to a given point and that ultrasound is going to attack light passing through the outside of tissue we detect attacked photons and time reverse the tagged photons back and it will come back to the outer assumed focal point so this technology is called time reversed ultrasound coded or true optical focusing in other technologies to use photo quistis as a guy star right so | 3,552 | 3,581 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3552s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | this this is called optical speckle right if you have a camera embedded in a piece of tissue this is what you would see in general yeah you got bright spots everywhere there there are actually a lot of photons down there even when it's deep but they're all spread all over the place so using this optical focus we can actually collect a lot of the bright spots and concentrate them onto this | 3,581 | 3,606 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3581s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | ultrasound focal spot if we were to use an your higher-order effect we catch you coalesce all of them into a single spot so this can be extremely powerful right so you here's the signal by 6000 times it's a huge enhancement one more possibility of finding a guy star is to use motion right so when there's blood flow freaks for example the blood flow can be used to serve as a guy starts | 3,606 | 3,641 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3606s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | moving so we have this cartoon if you have a plane behind a child for example can we actually track that plane right so using the motion of the object as a guy star itself all right let me spend a couple more slides talk about one last technology we're working on in fact this paper up here today I knew actually this our work made cover of the nature as we know this is the best scientific journal | 3,641 | 3,675 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3641s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | so we developed the technology that allows us to literally detect the fastest phenomenon possible right allowed by physics as we know Einstein's relativity theory says nothing can travel beyond the speed of light so we're detecting the light pulse itself and the light pulses are traveling in space at a speed of light we're capturing the light pulses as the light | 3,675 | 3,705 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3675s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | propagates in space get reflected by this mirror and if the my rate bends as a crosses interface of two media you can see the angles will change right or you've had two pulses in two media and we can watch them a race and see which one will fly will travel faster and here you know what I saw a green pulse traveling here it'll excite some fluorescence and this red spot is | 3,705 | 3,743 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3705s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | actually a fluorescent light so we're watching this fluorescent light to decay and with a single laser shot we observed this phenomenon even the force and decay is on the nanosecond scale because we have picosecond resolution so that nanosecond looks like eternity for us so this can be used for very high speed microscopy or you can potentially use this in combination with the Hubble | 3,743 | 3,770 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3743s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | telescope for example to look at very large phenomenon right like supernovae for example so this has very broad applications potentially and this is the technology we just developed I don't know how much detail we need to get into this maybe I should skip at this late hour you can ask me questions later if you're curious about this so I've covered a lot of different technologies | 3,770 | 3,803 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3770s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | here started with the motivation and challenges in your field I talked about photoacoustic CT photo QC microscopy in two forms time reversal and what we call cup compressed ultra-fast photography Washington University requires me to discuss my financial financial interest with two companies which have commercialized the photo because it photoacoustic tomography and | 3,803 | 3,834 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3803s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | we're funded by NIH through various projects thank you very much I'll be happy to entertain any questions if there's any oh it's hard for me to see so tissue imaging is the main goal for our research but you can potentially use it for some other applications even non biomedical right you can imagine robotic vision for underwater right so photo if there's turbidity what we call when | 3,834 | 3,917 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3834s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | there's a muddy water for example right you can't really see very far underwater so using photo acoustics so you can overcome the turbidity you fire some light pulses if your goal is to see a couple meters beyond you right so potentially like and propagate that for our generate acoustic waves then you can pick them pick that up and form an image does that answer your question | 3,917 | 3,944 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3917s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | okay and there was yeah back there please so it hurt you a light-induced sound so what happens is light is first absorbed so you generate a transient heating a very short temperature rice right so on the order of nano second scale because we use nanosecond laser pulses and so that temperature rises as you can imagine is gonna cause thermo elastic expansion and that pushes tissue even | 3,944 | 3,988 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3944s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | though this is very my new every milli degree gives you eight millibars or 800 Pascal's of pressure rice which is already detectable so if you generate hundreds of million degrees temperature rise then you get a very bright signal to detect and that allows us to form a image so this is called a photo acoustic effect so basically it's a photo thermal and thermal acoustic in the end that we | 3,988 | 4,012 | https://www.youtube.com/watch?v=NyoezBq14vE&t=3988s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | just call that photo acoustic affect the standard detectors has to be coupled acoustically to the tissue you can direct it touch it just like when you perform ultrasound imaging in the hospital they typically apply some gel on the skin to to ensure acoustic coupling water coupling is one way gel coupling is more convenient for a lot of applications however our field is also | 4,012 | 4,046 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4012s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | developing non-contact sensing of acoustic waves through optical interferometry so if you shine light on to the tissue surface if there's vibration on the surface that displacement can be picked up through optical interferometry and that can be translated into acoustic wave as well so that's a potential non-contact version for now most of the implementations are | 4,046 | 4,069 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4046s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | based on the contact version it's more traditional and it's better developed there's yeah please mm-hm so right now for breast cancer image in extra mammography is still the gold standard so we're still sticking with that one there are two types of directions that our field is taken one is to supplement extra mammography because x-ray mammography you know as | 4,069 | 4,125 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4069s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | since it's as sensitive as it is they have trouble with young women with reader graphically dense breast so where they really feel miserable the other flaw with x-ray mammography is the very high false positive rate so that causes a lot of you know biopsies you know subsequent tests which turned out to be unnecessary eventually so can we use photo acoustics to supplement right if | 4,125 | 4,157 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4125s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | x-ray detects this as positive can we confirm if this is truly positive or not by detecting the functional information another way that's more takes longer it's going to take longer to validate is to star from breast cancer screening to begin with so can we use photoacoustic tomography to screen for breast cancer without using ionizing radiation at all just start from from the functional | 4,157 | 4,187 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4157s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | contrast provided by photo acoustics the reason I said is going to take longer it's because even though breast cancer is a huge problem the rate of incidence is still relatively low you know you have to test like a thousand patients to get enough patients with breast cancer so you can establish the statistics so it's a more difficult problem any more questions | 4,187 | 4,214 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4187s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | yeah please all right images right yeah so it's a very good question your temp is still talking about photoacoustic tomography right so there are two different ways of getting an image with the microscopy technique with a single laser shot you get a 1d image which is depth resolved so you eliminate along the vertical axis for example then you generally the essentially a volumetric acoustic source | 4,214 | 4,265 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4214s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | but then we use ultrasound transducer to pick up the signals so the acoustic time of rival is gonna tell you the depth information you get a 1d image with a single laser shot then you have to use scan linearly to get a 2d image then you have the if you want to get a 3d image then you have the raster scan that's one way of getting an image 3d image another way is to use a ray of transducers so | 4,265 | 4,291 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4265s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | for example like the ringing array I showed right so we basically for the reign of 512 elements surrounding the head of animal or a body of animal or wherever we want an image like the breast then we use a broad field light illumination we don't focus light here at all we just light light photons basically bathe the tissue you generate the 3d volumetric source then your ring | 4,291 | 4,319 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4291s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | is going to detect signals from a slice because we acoustically focus in the elevational direction the height direction and then we detect signal from the from this slice then we use image reconstruction to form a 2d image and if you want to get a third dimension of course you do the scan now this is a way the 1d array now if budget is not a problem then we can potentially get a 2d | 4,319 | 4,346 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4319s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | array I mean in the ideal world that you imagine we could surround the brass or the head with a lot of transducers in that case with a single laser shot you should be able to get a 3d image but right now the the technology allows us to get a ring array or 1d array at a reasonable price but a two-dimensional array is I know quite expensive in fact the ultrasound world has been working on | 4,346 | 4,373 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4346s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | that for quite some time and they're talking about one happy in other words one dimensional density is high the second dimensional density is much lower because you simply cannot have that many transducers ultrasound transducers and still maintain the cost yeah please mm-hmm so I I was trained in laser physics so I got my PhD from rice and I my PhD thesis was actually on my chemistry project | 4,373 | 4,429 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4373s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | after I got my PhD I decided to switch to something more applied so I worked for MD Anderson Cancer Center there was a laser lab I think that was a very good fit for my career goal so for applications in ori i think there are several potential applications so one of them is the cancer demarcation as I mentioned can we have a complete removal tumor so you minimize the recurrence | 4,429 | 4,462 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4429s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | rate another application as summation is the bring oxygen consumption monitoring we want to do that now you basically so this is what's so good about Wash U right so even though most of my lab spaces in the hilltop or Danforth campus I have a lab in the medical school as well we have a lot of collaborators you know so physicians Wash U physicians are very eager to work with engineers they | 4,462 | 4,496 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4462s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | want to work with us the knock on my door come to my office want to work with engineers to apply our technology to their problems so we're targeting multiple problems it GI tract breast you know breast cancer staging melanoma you name it so we want to see the real impact in the human side the photo acoustic tomography has been commercialized by several companies now | 4,496 | 4,525 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4496s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
NyoezBq14vE | I personally work with two of them so for preclinical imaging it has been you know established so there are products available they are being sold for a human imaging it's not there yet so I was not allowed to mention the name of the company which has licensed our IP for human imaging but so we're very happy that this is moving forward so it's going to take some time eventually I'd like to | 4,525 | 4,555 | https://www.youtube.com/watch?v=NyoezBq14vE&t=4525s | Reversing Time, Photoacoustics and Other Optical Breakthroughs in Biomedical Imaging | |
5QaOt56cWhg | John I believe a lot of things everything I believe I think is true but if I stop to think about it what do I mean by a belief what is the nature of belief yeah well I think as you know the mind is a biological phenomenon so belief is part of the biology of the mind and you won't understand belief unless you see it in relation to other parts of the biology of the mind now I | 0 | 22 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=0s | John Searle - What is Belief? | |
5QaOt56cWhg | have to introduce an ugly word here intentionality and that sounds like it's a fancy thing it just means the capacity by which the mind represents objects and states of affairs so beliefs and hopes and fears and desires and love and hate and lust and discussion those are all intentional now that suggests they've got something to with intending but that's just an accident of history we | 22 | 41 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=22s | John Searle - What is Belief? | |
5QaOt56cWhg | got this word from the Germans and like most of our confused words in philosophy I and in German intentionality doesn't sound like a position that's the word for intention so forget about the connection with intending and just think there is this capacity that the mind has to represent and it does that in a variety of ways and belief is one of the most important a belief in desire are | 41 | 62 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=41s | John Searle - What is Belief? | |
5QaOt56cWhg | kind of matching concepts here because with belief we represent how things are or how we think they are and that has the mind to world direction of v am I supposed to fit the world but with desires we represent not how we think things are but how we want them to be and that desire has the world to mind direction of it the world is supposed to change to match the mind now how then | 62 | 85 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=62s | John Searle - What is Belief? | |
5QaOt56cWhg | does all of this work as a totality all of these intentional States well I can't ask that question briefly it's too big a question but I can tell you some features beliefs are characteristically I justified beliefs required justification in a way that desires and hunches don't and beliefs are currently justified by their position within a network of other beliefs and other | 85 | 111 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=85s | John Searle - What is Belief? | |
5QaOt56cWhg | intentional states and above all a network that contains perception so you see that the dog is in the living room and that is a kind of a boring belief but you come to the believing the dog is in the living room so you have beliefs that are both related to your perceptions and also many of your beliefs are derived related to other beliefs I believe that Barack Obama is active in the government | 111 | 140 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=111s | John Searle - What is Belief? | |
5QaOt56cWhg | because I also believe he's president the United States but now the remarkable thing is that with beliefs there's a peculiar rational constraint in that the belief is not only caused by perception which is often the case but the belief is itself subject to rational assessment depending on not just what you've seen but what you've read and what you know otherwise and what seems reasonable and | 140 | 166 | https://www.youtube.com/watch?v=5QaOt56cWhg&t=140s | John Searle - What is Belief? |
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