1. Articles from Yu Chen

    1-24 of 69 1 2 3 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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      Mentions: Wei Wang
    10. 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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    11. 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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    12. 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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    13. Validation of Human Small Airway Measurements Using Endobronchial Optical Coherence Tomography

      Validation of Human Small Airway Measurements Using Endobronchial Optical Coherence Tomography

      PURPOSE: To evaluate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessing small airways morphology in vivo. METHODS: Twelve patients with pulmonary nodules scheduled for lung resection underwent spirometry, multidetector computed tomography (MDCT) and EB-OCT. We measured Dmean (mean luminal diameter), Ai (inner luminal area), Aw (airway wall area) and Aw% [Aw/(Ai+Aw) ×100%] from the 3rd to 5th generation bronchi of RB9 segment by MDCT. Dmean, Ai, Aw and Aw% from the 3rd to 9th generation bronchi of RB9 segment were measured by EB-OCT and histology. The correlations of these 4 parameters, measured by the three methods ...

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    14. OCT imaging of myocardium extending to pulmonary vein

      OCT imaging of myocardium extending to pulmonary vein

      In this study, we propose to use optical coherence tomography to enable a direct visualization of myocardium extending into the pulmonary vein (PV). The results showed that there are obvious differences in the morphology of myocardium and fibrous tissue in the transition region of myocardial sleeve, which is in agreement with the histological analysis. In addition, the myocardial area in transition point has three layers in the depth of 1 mm, and the depth-resolved myocardial fiber show different orientation in the different layers. This characteristic was applied for segmentation of the structures of myocardium extending into PV.

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    15. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

      A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2–5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish ...

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    16. Optical Coherence Tomographic Elastography Reveals Mesoscale Shear Strain Inhomogeneities in the Annulus Fibrosus

      Optical Coherence Tomographic Elastography Reveals Mesoscale Shear Strain Inhomogeneities in the Annulus Fibrosus

      Study Design. Basic science study using in vitro tissue testing and imaging to characterize local strains in annulus fibrosus (AF) tissue. Objective. To characterize mesoscale strain inhomogeneities between lamellar and inter-/translamellar (ITL) matrix compartments during tissue shear loading. Summary of Background Data. The intervertebral disc (IVD) is characterized by significant heterogeneities in tissue structure and plays a critical role in load distribution and force transmission in the spine. In particular, the AF possesses a lamellar architecture interdigitated by a complex network of extracellular matrix components that form a distinct ITL compartment. Currently, there is not a firm understanding of ...

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    17. Validation of human small-airway measurements using endobronchial optical coherence tomography: an observational study

      Validation of human small-airway measurements using endobronchial optical coherence tomography: an observational study

      Background Small-airway remodelling is the cardinal pathological feature underlying chronic obstructive pulmonary disease (COPD). Identification of early-stage pathological changes is crucial for the diagnosis, treatment, and prognosis of respiratory diseases. Our study aimed to investigate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessment of small-airways morphology in patients with pulmonary nodules who were scheduled for lung resection surgery (four had COPD, four were smokers with normal lung function, and four were life-long non-smokers). Patients with respiratory diseases other than COPD were excluded. Methods 12 patients with pulmonary nodules scheduled for lung resection underwent spirometry, multidetector CT (MDCT), and ...

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      Mentions: Yu Chen Wei Wang
    18. Validation of human small airway measurements using endobronchial optical coherence tomography

      Validation of human small airway measurements using endobronchial optical coherence tomography

      Background Small airway remodeling is the cardinal feature underlying chronic airway diseases. There is no modality which identifies small airway pathological changes, which is crucial for early diagnosis, efficacy and prognostic assessment. Objective To evaluate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessing small airways morphology in vivo . Methods Twelve patients with pulmonary nodules scheduled for lung resection underwent spirometry, multi-detector computed tomography (MDCT) and EB-OCT. We measured D mean (mean luminal diameter), Ai (inner luminal area), Aw (airway wall area) and Aw% [Aw/(Ai + Aw) × 100%] from the 3rd to 5th generation bronchi of RB9 segment by ...

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    19. Apparatus And Methods For NON-INVASIVE Assessment Of Transplant Kidney Viability

      Apparatus And Methods For NON-INVASIVE Assessment Of Transplant Kidney Viability

      A kidney viability assessment system (KVAS) is disclosed which provides objective and reliable tests to assess the viability of transplant or donor kidneys in vivo and predict their post-transplant outcomes. KVAS includes an optical device augmented by an intelligent algorithm that can evaluate the viability or quality of the donor kidney in a real-time, non-invasive way. In particular, it includes a handheld optical coherence tomography (OCT) imaging device and at least one processor configured for executing a set of instructions corresponding to an automatic image processing algorithm for quantification of kidney microstructures and functions. Handheld OCT can survey the entire ...

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    20. Quantitative single-mode fiber based PS-OCT with single input polarization state using Mueller matrix

      Quantitative single-mode fiber based PS-OCT with single input polarization state using Mueller matrix

      We present a simple but effective method to quantitatively measure the birefringence of tissue by an all single-mode fiber (SMF) based polarization-sensitive optical coherence tomography (PS-OCT) with single input polarization state. We theoretically verify that our SMF based PS-OCT system can quantify the phase retardance and optic axis orientation after a simple calibration process using a quarter wave plate (QWP). Based on the proposed method, the quantification of the phase retardance and optic axis orientation of a Berek polarization compensator and biological tissues were demonstrated.

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    21. Technology developments and biomedical applications of polarization-sensitive optical coherence tomography

      Technology developments and biomedical applications of polarization-sensitive optical coherence tomography

      Polarization-sensitive optical coherence tomography (PS-OCT) enables depth-resolved mapping of sample polarization information, such as phase-retardation and optical axis orientation, which is particularly useful when the nano-scale organization of tissue that are difficult to be observed in the intensity images of a regular optical coherence tomography (OCT). In this review, we survey two types of methods and systems of PS-OCT. The first type is PS-OCT with single input polarization state, which contain bulk optics or polarization maintaining fiber (PMF) based systems and single-mode fiber (SMF) based systems. The second type is PS-OCT with two different input polarization states, which contain SMF ...

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    22. Real-time epidural anesthesia guidance using optical coherence tomography needle probe

      Real-time epidural anesthesia guidance using optical coherence tomography needle probe

      Epidural anesthesia is one of the most widely used anesthesia methods. Due to lack of visual feedback to guide needle navigation, failure rate of epidural anesthesia is up to 20%, and the complication rate of peripheral nerve block approaches 10%, with the potential of permanent nerve damage. To address these difficulties, needle insertion under ultrasound guidance and fluoroscopy has been introduced. However, they do not provide adequate resolution and contrast to distinguish the tissue layers that the needle travels through or to specifically identify the epidural space. To improve the accuracy of epidural space identification, we developed a small hand-held ...

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    23. Three dimensional mesoscale analysis of translamellar cross-bridge morphologies in the annulus fibrosus using optical coherence tomography

      Three dimensional mesoscale analysis of translamellar cross-bridge morphologies in the annulus fibrosus using optical coherence tomography

      The defining characteristic of the annulus fibrosus (AF) of the intervertebral disc (IVD) has long been the lamellar structures that consist of highly ordered collagen fibers arranged in alternating oblique angles from one layer to the next. However, a series of recent histologic studies have demonstrated that AF lamellae contain elastin- and type VI collagen-rich secondary “cross-bridge” structures across lamellae. In this study, we use optical coherence tomography (OCT) to elucidate the three-dimensional (3-D) morphologies of these translamellar cross-bridges in AF tissues. Mesoscale volumetric images by OCT revealed a 3-D network of heterogeneously distributed cross-bridges. The results of this study ...

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    24. PhD Student and/or Postdoc Position at University of Maryland

      PhD Student and/or Postdoc Position at University of Maryland

      The Biophotonics Imaging Lab at the University of Maryland (College Park, USA) is looking for motivated PhD students and/or postdoc associates to join our group. UMD Engineering School ranks top 20 in the US. Our research program integrates basic optical imaging technology development, translational imaging/sensing devices, pre-clinical / clinical applications, and regulatory sciences. The specific research project will be jointly developed between the PI and the interested student/postdoc. Projects may be chosen from one or the combination of the following topics: • Optical Imaging Technologies o Optical Coherence Tomography (OCT) o Multiphoton Microscopy (MPM) o Needle-based Endoscopy • Biomedical Applications ...

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    1-24 of 69 1 2 3 »
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    1. (63 articles) Yu Chen
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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 Integrated Optical Coherence Tomography (OCT) and Fluorescence Laminar Optical Tomography (FLOT) 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 Dutch Health-Care Startup Scinvivo to present at DMD 2017 Europe on "Improving bladder cancer diagnostics with an Optical Coherence Tomography imaging catheter" Conavi Medical and China Grand Pharmaceutical and Healthcare Enter into Distribution Agreement for Minimally Invasive Imaging Technologies in China Detecting Structural Progression in Glaucoma with Optical Coherence Tomography Simulating optical coherence tomography for observing nerve activity: a finite difference time domain bi-dimensional model