1. Articles from Yu Chen

    1-24 of 81 1 2 3 4 »
    1. Digital Gonioscopy based on Three-dimensional Anterior Segment Optical Coherence Tomography: an international multicenter study

      Digital Gonioscopy based on Three-dimensional Anterior Segment Optical Coherence Tomography: an international multicenter study

      Objective: To develop and evaluate the performance of a three-dimensional deep-learning based automated digital gonioscopy system (3D DGS) in detecting two major characteristics in eyes suspected to have primary angle closure glaucoma (PACG): 1) narrow iridocorneal angles (static gonioscopy, Task I) and; 2) peripheral anterior synechiae (PAS) (dynamic gonioscopy, Task II) on optical coherence tomography scans. Design: International cross-sectional multicentre study. Subjects: A total of 1.112 million images of 8694 volume scans (2294 patients) from three centers were included in this study (Task I: training/internal validation/external testing - 4515, 1101, 2222 volume scans respectively; Task II: training/internal ...

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    2. Indoor localization of hand-held OCT probe using visual odometry and real-time segmentation using deep learning

      Indoor localization of hand-held OCT probe using visual odometry and real-time segmentation using deep learning

      Objective: Optical coherence tomography (OCT) is an established medical imaging modality that has found widespread use due to its ability to visualize tissue structures at a high resolution. Currently, OCT hand-held imaging probes lack positional information, making it difficult or even impossible to link a specific image to the location it was originally obtained. In this study, we propose a camera-based localization method to track and record the scanner position in real-time, as well as providing a deep learning-based segmentation method. Methods: We used camera-based visual odometry (VO) and simultaneous mapping and localization (SLAM) to compute and visualize the location ...

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    3. Quantitative analysis of vascular changes during photoimmunotherapy using speckle variance optical coherence tomography (SV-OCT)

      Quantitative analysis of vascular changes during photoimmunotherapy using speckle variance optical coherence tomography (SV-OCT)

      Near-infrared (NIR) photoimmunotherapy (NIR-PIT) is an emerging cancer therapy based on a monoclonal antibody and phthalocyanine dye conjugate. Direct tumor necrosis and immunogenic cell death occur during NIR irradiation. However, the alteration of tumor blood vessels and blood volume inside the blood vessels induced by the NIR-PIT process is still unknown. In our study, a speckle variance (SV) algorithm combined with optical coherence tomography (OCT) technology was applied to monitor the change of blood vessels and the alterations of the blood volume inside the blood vessels during and after NIR-PIT treatment. Vascular density and the measurable diameter of the lumen ...

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    4. Longitudinal Changes in Macular Optical Coherence Tomography Angiography Metrics in Primary Open-Angle Glaucoma With High Myopia: A Prospective Study

      Longitudinal Changes in Macular Optical Coherence Tomography Angiography Metrics in Primary Open-Angle Glaucoma With High Myopia: A Prospective Study

      Purpose : To characterize longitudinal changes in macular microvasculature as quantified from optical coherence tomography angiography (OCTA) metrics in primary open-angle glaucoma (POAG) eyes with and without high myopia. Methods : In total, 63 and 61 POAG eyes with and without high myopia, respectively, underwent swept-source OCTA imaging in at least four follow-up visits at an ophthalmic center, with a scanning protocol of 3- × 3-mm centered at the fovea. The foveal avascular zone (FAZ) area, FAZ circularity, and vessel density (VD) in both the superficial (SCP) and deep capillary plexuses (DCP) were measured. The rate of change in macular OCTA metrics over ...

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    5. Optical coherence tomography (OCT) system with improved image quality

      Optical coherence tomography (OCT) system with improved image quality

      This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to an OCT system that generates an image with improved quality. In one example, the OCT system may generate an improved Bscan image by using multiple shaping functions to shape the raw A-scans. In another example, the OCT system may generate the improved B-scan image by forming multiple apodization patterns on a detector and acquiring raw A-scans by using the apodization patterns. A better diagnosis of a health condition may be reached by using the improved images generated by the OCT system of this disclosure.

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    6. Evaluation of the normal airway morphology using optical coherence tomography

      Evaluation of the normal airway morphology using optical coherence tomography

      Background The anatomical location of small airways, the distribution of airway cartilage and their correlation with ageing have not been well elucidated. Objective To explore the morphological characteristics of small airways in vivo , and how airway structural changes correlate with age using endobronchial optical coherence tomography (EB-OCT). Methods We recruited 112 subjects with peripheral pulmonary nodules. Participants underwent computed tomography, spirometry, and EB-OCT measurements. We measured the airway internal diamaeter (D mean ), inner area (Ai), airway wall area percentage (Aw%) and the thickness of airway cartilage. EB-OCT airway structural characteristics at different age intervals were analyzed, and the association between ...

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    7. PhD Student and Postdoctoral Associate Positions at the University of Massachusetts

      PhD Student and Postdoctoral Associate Positions at the University of Massachusetts

      We are looking for highly motivated individuals to join the Biophotonics Imaging Laboratory at UMass Amherst and Worcester. Our lab has interdisciplinary biomedical engineering research programs focusing on the development of novel optical imaging methods for biomedical applications, including functional neuroimaging, early cancer detection, transplant organ evaluation, and tissue engineering. Our optical imaging technologies include optical coherence tomography (OCT), multi-photon microscopy (MPM), fluorescence molecular imaging (FMI), laminar optical tomography (LOT), and endoscopy. A detailed description of our research can be found at: http://blog.umd.edu/biophotonics/research/ Candidates with experiences on biomedical engineering, optical engineering, and/or electrical/mechanical ...

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    8. Significances of spirometry and impulse oscillometry for detecting small airway disorders assessed with endobronchial optical coherence tomography in COPD

      Significances of spirometry and impulse oscillometry for detecting small airway disorders assessed with endobronchial optical coherence tomography in COPD

      Background: Spirometry confers limited value for identifying small-airway disorders (SADs) in early-stage COPD, which can be detected with impulse oscillometry (IOS) and endobronchial optical coherence tomography (EB-OCT). Whether IOS is useful for reflecting small-airway morphological abnormalities in COPD remains unclear. Objectives: To compare the diagnostic value of spirometry and IOS for identifying SADs in heavy-smokers and COPD based on the objective assessment with EB-OCT. Methods: We recruited 59 COPD patients (stage I, n=17; stage II, n=18; stage III–IV, n=24), 26 heavy-smokers and 21 never-smokers. Assessments of clinical characteristics, spirometry, IOS and EB-OCT were performed. Receiver operation ...

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    9. Depth-resolved mapping of muscular bundles in myocardium pulmonary junction using optical coherence tomography

      Depth-resolved mapping of muscular bundles in myocardium pulmonary junction using optical coherence tomography

      Atrial fibrillation (AF) is the most common cardiac arrhythmia and has high patient morbidity. One of the root causes of AF is initiating triggers from atrial myocardium extending into the pulmonary veins. Visualizing the muscular bundles of myocardial extension is essential to guide the catheter radio-frequency ablation and confirm the curative tissue necrosis thereafter. We applied optical coherence tomography (OCT) for direct visualization of cardial muscle extension in myocardium pulmonary junction. Two perspectives (cross-sectional and en face images) are presented for imaging myocardial extensions. The results demonstrated that cross-sectional images can quickly locate the myocardium pulmonary junction. And en face ...

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    10. 3D mesoscopic fluorescence tomography for imaging micro-distribution of antibody-photon absorber conjugates during near infrared photoimmunotherapy in vivo

      3D mesoscopic fluorescence tomography for imaging micro-distribution of antibody-photon absorber conjugates during near infrared photoimmunotherapy in vivo

      As a novel low-side-effect cancer therapy, photo-immunotherapy (PIT) is based on conjugating monoclonal antibody (mAb) with a near-infrared (NIR) phthalocyanine dye IRDye700DX (IR 700). IR700 is not only fluorescent to be used as an imaging agent, but also phototoxic. When illuminating with NIR light, PIT can induce highly-selective cancer cell death while leaving most of tumor blood vessels unharmed, leading to an effect termed super-enhanced permeability and retention (SUPR), which can significantly improve the effectiveness of anti-cancer drug. Currently, the therapeutic effects of PIT are monitored using 2D macroscopic fluorescence reflectance imager, which lacks the resolution and depth information to ...

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    11. Optical coherence tomography and computer-aided diagnosis of a murine model of chronic kidney disease

      Optical coherence tomography and computer-aided diagnosis of a murine model of chronic kidney disease

      Chronic kidney disease (CKD) is characterized by a progressive loss of renal function over time. Histopathological analysis of the condition of glomeruli and the proximal convolutional tubules over time can provide valuable insights into the progression of CKD. Optical coherence tomography (OCT) is a technology that can analyze the microscopic structures of a kidney in a nondestructive manner. Recently, we have shown that OCT can provide real-time imaging of kidney microstructures in vivo without administering exogenous contrast agents. A murine model of CKD induced by intravenous Adriamycin (ADR) injection is evaluated by OCT. OCT images of the rat kidneys have ...

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    12. Multi-shaping technique reduces sidelobe magnitude in optical coherence tomography

      Multi-shaping technique reduces sidelobe magnitude in optical coherence tomography

      Shaping methods that are commonly used in Fourier-domain optical coherence tomography (FD-OCT) can suppress sidelobe artifacts in the axial direction, but they typically broaden the mainlobe of the point spread function (PSF) and reduce the axial resolution. To improve OCT image quality without this tradeoff, we have developed a multi-shaping technique that reduces the axial sidelobe magnitude dramatically and achieves better axial resolution than conventional shaping methods. This technique is robust and compatible in various FD-OCT imaging systems. Testing of multi-shaping in three experimental settings shows that it reduced the axial sidelobe contribution by more than 8 dB and improved ...

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      Mentions: UCLA
    13. Monitoring Kidney Microanatomy Changes During Ischemia-Reperfusion Process Using Texture Analysis of OCT Images

      Monitoring Kidney Microanatomy Changes During Ischemia-Reperfusion Process Using Texture Analysis of OCT Images

      Impact Statement: Tubular diameter has been developed previously as a potential biomarker for the transplant kidney. However, the tubular lumens were segmented out based on an empirically-determined threshold. In our study, a fully automatic texture analysis algorithm has been developed for OCT image analysis of kidney microanatomy during ischemia-reperfusion process. Our method can potentially be applicable in evaluating the status of donor kidneys prior to and after their transplantation. Abstract: Kidney ischemia-reperfusion (I/R) accounts for the majority of acute kidney injury cases, whose consequences are commonly encountered after kidney transplantation. Optical coherence tomography (OCT) has been applied to image ...

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    14. Postdoctoral Fellow, Bioengineering at University of Maryland - College Park

      Postdoctoral Fellow, Bioengineering at University of Maryland - College Park

      We are seeking a postdoctoral fellow to pursue research on developing novel optical imaging devices and applications on cancer diagnosis, functional brain imaging and tissue engineering. Candidates must hold a Ph.D. in engineering, physics, or related fields and have prior experience with Optics, OCT, Microscopy (e.g. fluorescence, confocal, Two-photon), and image analysis software development. Experience with cell culture and/or animals experiments is a plus. Please submit a cover letter with a brief description of research experience, interests, and career goals (≤ 2 pages), CV with complete list of publications, and contact information for 3 references in a single ...

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    15. 3D in vivo imaging with extended-focus optical coherence microscopy

      3D in vivo imaging with extended-focus optical coherence microscopy

      Optical coherence microscopy (OCM) has unique advantages of non-invasive 3D imaging without the need of exogenous labels for studying biological samples. However, the imaging depth of this technique is limited by the tradeoff between the depth of focus (DOF) and high lateral resolution in Gaussian optics. To overcome this limitation, we have developed an extended-focus OCM (xf-OCM) imaging system using quasi-Bessel beam illumination to extend the DOF to ∼100 μm, about 3-fold greater than standard OCM. High lateral resolution of 1.6 μm ensured detailed identification of structures within live animal samples. The insensitivity to spherical aberrations strengthened the capability ...

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    16. Optical coherence microscopy with extended focus for in vivo embryonic imaging

      Optical coherence microscopy with extended focus for in vivo embryonic imaging

      Optical coherence microscopy (OCM) has unique advantages of high-resolution volumetric imaging without relying on exogenous labels or dyes. It combines the coherence-gated depth discrimination of optical coherence tomography (OCT) with the high lateral resolution of confocal microscopy, offering an excellent balance between the resolutions and imaging depth. However, as the lateral resolution becomes higher, the imaging depth of OCM decreases and its three-dimensional imaging capability is greatly degraded. To overcome this limitation, we used amplitude apodization to create quasi-Bessel beam illumination in order to extend the depth of focus. The lateral and axial resolutions of our OCM system were measured ...

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    17. Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos

      Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos

      A phase variance optical coherence microscope (pvOCM) has been created to image blood flow in the microvasculature of zebrafish embryos, without the use of exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2.8    μ m 2.8  μm in tissue and imaging depth of more than 100    μ m 100  μm . Images of 2 to 5 days postfertilization zebrafish embryos identified the detailed anatomical structure based on OCM intensity contrast. Phase variance contrast offered visualization of blood flow in the arteries, veins, and capillaries. The pvOCM images of the vasculature were confirmed by direct comparisons with fluorescence ...

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    18. Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography

      Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography

      Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is difficult to detect the subsurface lesions. In this research, we investigated the feasibility of a novel multi-modal optical imaging approach including high-resolution optical coherence tomography (OCT) and high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. The C57BL/6J-Apc Min /J mice were imaged using OCT and FLOT, and the correlated histopathological diagnosis was obtained. Quantitative structural (scattering coefficient) and molecular (relative enzyme activity ...

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    19. Imaging Spinal Structures With Polarization-Sensitive Optical Coherence Tomography

      Imaging Spinal Structures With Polarization-Sensitive Optical Coherence Tomography

      Impact Statement: We investigate polarization-sensitive optical coherence tomography (PS-OCT) to obtain both intensity and polarization contrast images of in vivo and ex vivo spinal structures like subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, dura, and spinal cord in a piglet model. The PS-OCT can provide enhanced contrast characteristic structures compared to the intensity OCT; therefore it has the potential for guidance in spine interventional procedures. Abstract: We investigate polarization-sensitive optical coherence tomography (PS-OCT) to obtain both intensity and polarization contrast images of in vivo and ex vivo spinal structures like subcutaneous fat, supraspinous ligament, interspinous ligament, ligamentum flavum, dura ...

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    20. Measuring Airway Remodeling in Patients with Different COPD Staging Using Endobronchial Optical Coherence Tomography

      Measuring Airway Remodeling in Patients with Different COPD Staging Using Endobronchial Optical Coherence Tomography

      Background Although forced expiratory volume in one second (FEV 1 ) remains the gold standard for staging COPD, the association between airway remodeling and airflow limitation remains unclear. Objective Endobronchial optical coherence tomography (EB-OCT) was performed to assess the association between disorders of large- and medium-to-small-sized airways and COPD staging. We also evaluated small-airway architecture in heavy-smokers with normal FEV 1 (S NL ) and healthy never-smokers. Methods We recruited 48 COPD patients (stage Ⅰ, n=14; stage Ⅱ, n=15; stage Ⅲ-Ⅳ, n=19), 21 S NL , and 17 healthy never-smokers. Smoking history inquiry, spirometry, chest computed tomography, bronchoscopy and EB-OCT ...

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    21. Multi-modality Optical Imaging of Rat Kidney Dysfunction: In Vivo Response to Various Ischemia Times

      Multi-modality Optical Imaging of Rat Kidney Dysfunction: In Vivo Response to Various Ischemia Times

      We observed in vivo kidney dysfunction with various ischemia times at 30, 75, 90, and 120 min using multi-modality optical imaging: optical coherence tomography (OCT), Doppler OCT (DOCT), and two-photon microscopy (TPM). We imaged the renal tubule lumens and glomerulus at several areas of each kidney before, during, and after ischemia of 5-month-old female Munich-Wistar rats. For animals with 30 and 75 min ischemia times, we observed that all areas were recovered after ischemia, that tubule lumens were re-opened and the blood flow of the glomerulus was re-established. For animals with 90 and 120 min ischemia times, we observed unrecovered ...

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    22. Research Associate Position in OCT at the University of Maryland

      Research Associate Position in OCT at the University of Maryland

      Position description: A Postdoctoral Research Associate position is available at the University of Maryland, College Park. Research projects include intraoperative imaging of transplant kidney viability using OCT in collaboration with Georgetown University Medical Center, and development of automatic image processing algorithm to predict organ viability. Required expertise: Ph.D. in physics, electrical engineering, optical engineering, or biomedical/bioengineering. Hand-on experience on optical and electronic instrumentation and strong programming skills (Matlab, Labview, and C++). Prior research expertise on OCT and image processing. Application: Interested candidates should submit Curriculum vitae with a list of contact information of 3 references by email to ...

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    23. Optical Coherence Tomography of the Aging Kidney

      Optical Coherence Tomography of the Aging Kidney

      Objectives: The aging kidney exhibits a progressive decline in renal function with characteristic histopathologic changes and is a risk factor for renal transplant. However, the degree to which the kidney exhibits this decline depends on several factors that vary from one individual to the next. Optical coherence tomography is an evolving noninvasive imaging technology that has recently been used to evaluate acute tubular necrosis of living-human donor kidneys before their transplant. With the increasing use of kidneys from older individuals, it is important to determine whether optical coherence tomography also can distinguish the histopathology associated with aging. Materials and Methods ...

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    Effects of axial resolution improvement on optical coherence tomography (OCT) imaging of gastrointestinal tissues Feature Of The Week 9/6/09: Automated Quantification of Microstructural Dimensions of the Human Kidney using Optical Coherence Tomography Investigation of pore structure and cell distribution in EH-PEG hydrogel scaffold using optical coherence tomography and fluorescence microscopy Cellular resolution ex vivo imaging of gastrointestinal tissues with optical coherence microscopy Optical Coherence Tomography of Human Kidney Congratulations to Chia-Pin Liang From the University of Maryland a Winner of a 2012 Student Travel Grant Award Research Associate Position in OCT at the University of Maryland New insights from non-invasive imaging: from prospection of skin photodamages to training with mobile application Short-sighted woman assumes debilitating headaches mean she needs new glasses but discovers she has multiple sclerosis Shedding light on the impact of microplastics on lentil seedling growth Comparison of radial peripapillary capillary density results of individuals with and without Helicobacter pylori infection Ai, Oct Operate in Tandem to Detect Plaque Erosion in the Heart