All Articles from Yu Chen -Optical Coherence Tomography News

Articles from Yu Chen

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1. 3D in vivo imaging with extended-focus optical coherence microscopy
  
  Explore Wiley Online Library Apr 25 2017
  
  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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  Mentions: University of Southern California Scott E. Fraser
2. Optical coherence microscopy with extended focus for in vivo embryonic imaging
  
  Explore Conference Proceedings Feb 16 2017 Developmental Biology , Microscopy
  
  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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  Mentions: University of Southern California Yu Chen Scott E. Fraser
3. Phase variance optical coherence microscopy for label-free imaging of the developing vasculature in zebrafish embryos
  
  Explore SPIE | Journal Jan 3 2017 Developmental Biology
  
  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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  Mentions: University of Southern California Scott E. Fraser
4. Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography
  
  Explore OSA | OSA Publishing Dec 27 2016 Gastroenterology
  
  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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  Mentions: University of Maryland University of Rochester Harvard University
5. Imaging Spinal Structures With Polarization-Sensitive Optical Coherence Tomography
  
  Explore IEEE Xplore Sep 27 2016 Neurology
  
  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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  Mentions: University of Maryland Yu Chen Fujian Normal University
6. Measuring Airway Remodeling in Patients with Different COPD Staging Using Endobronchial Optical Coherence Tomography
  
  Explore ScienceDirect Aug 16 2016 Pulmonology
  
  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
7. Multi-modality Optical Imaging of Rat Kidney Dysfunction: In Vivo Response to Various Ischemia Times
  
  Explore Home - Springer Aug 16 2016 Developmental Biology , Urology
  
  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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  Mentions: University of Maryland Yu Chen Tianjin University
8. Research Associate Position in OCT at the University of Maryland
  
  Explore Optical Coherence Tomography News Jun 13 2016 Jobs & Studentships
  
  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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  Mentions: University of Maryland Yu Chen Georgetown University
9. Optical Coherence Tomography of the Aging Kidney
  
  Explore ectrx.org May 5 2016 Urology
  
  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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  Mentions: University of Maryland Yu Chen
10. Validation of Human Small Airway Measurements Using Endobronchial Optical Coherence Tomography
  
  Explore CHEST Journal Apr 21 2016 Pulmonology
  
  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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  Mentions: University of Maryland
11. OCT imaging of myocardium extending to pulmonary vein
  
  Explore Conference Proceedings Apr 1 2016
  
  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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  Mentions: University of Maryland Yu Chen Fujian Normal University
12. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy
  
  Explore Conference Proceedings Mar 13 2016 Developmental Biology , 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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  Mentions: University of Southern California Yu Chen Scott E. Fraser
13. Optical Coherence Tomographic Elastography Reveals Mesoscale Shear Strain Inhomogeneities in the Annulus Fibrosus
  
  Explore LWW Online Feb 7 2016
  
  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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  Mentions: University of Maryland Yu Chen Chao-Wei Chen
14. Validation of human small-airway measurements using endobronchial optical coherence tomography: an observational study
  
  Explore TheLancet.com Nov 3 2015 Pulmonology
  
  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
15. Validation of human small airway measurements using endobronchial optical coherence tomography
  
  Explore Respiratory Medicine Sep 30 2015 Pulmonology
  
  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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  Mentions: University of Maryland Yu Chen Wei Wang
16. Apparatus And Methods For NON-INVASIVE Assessment Of Transplant Kidney Viability
  
  Explore patentscope.wipo.int Jul 24 2015 Urology , Patents
  
  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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  Mentions: University of Maryland Yu Chen Jeremiah Wierwille
17. Quantitative single-mode fiber based PS-OCT with single input polarization state using Mueller matrix
  
  Explore opticsinfobase.org Apr 22 2015
  
  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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  Mentions: University of Maryland Yu Chen Tianjin University
18. Technology developments and biomedical applications of polarization-sensitive optical coherence tomography
  
  Explore Home - Springer Apr 14 2015
  
  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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  Mentions: University of Maryland National Institutes of Health University of Pennsylvania
19. Real-time epidural anesthesia guidance using optical coherence tomography needle probe
  
  Explore AME Publishing Company Feb 21 2015 Probes
  
  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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  Mentions: University of Maryland Yu Chen Chia-Pin Liang
20. Three dimensional mesoscale analysis of translamellar cross-bridge morphologies in the annulus fibrosus using optical coherence tomography
  
  Explore Wiley Online Library Jan 9 2015
  
  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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  Mentions: University of Maryland National Institutes of Health Yu Chen
21. PhD Student and/or Postdoc Position at University of Maryland
  
  Explore Optical Coherence Tomography News Nov 1 2014 Jobs & Studentships
  
  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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  Mentions: University of Maryland National Institutes of Health Harvard University
22. Real-time monitoring of hemodynamic changes in tumor vessels during photoimmunotherapy using optical coherence tomography
  
  Explore SPIE | Journal Sep 26 2014
  
  Photoimmunotherapy (PIT) is a cell-specific cancer therapy based on an armed antibody conjugate that induces rapid and highly selective cancer cell necrosis after exposure to near-infrared (NIR) light. The PIT treatment also induces the superenhanced permeability and retention effect, which allows high concentrations of nanoparticles to accumulate in the tumor bed. In our pilot studies, optical coherence tomography (OCT) reveals dramatic hemodynamic changes during PIT. We developed and applied speckle variance analysis, Doppler flow measurement, bulk motion removal, and automatic region of interest selection to quantify vessel diameter and blood velocity within tumors in vivo . OCT imaging reveals that blood ...
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  Mentions: University of Maryland National Cancer Institute National Institutes of Health
23. Variations in optical coherence tomography resolution and uniformity: a multi-system performance comparison
  
  Explore opticsinfobase.org Jun 9 2014
  
  Point spread function (PSF) phantoms based on unstructured distributions of sub-resolution particles in a transparent matrix have been demonstrated as a useful tool for evaluating resolution and its spatial variation across image volumes in optical coherence tomography (OCT) systems. Measurements based on PSF phantoms have the potential to become a standard test method for consistent, objective and quantitative inter-comparison of OCT system performance. Towards this end, we have evaluated three PSF phantoms and investigated their ability to compare the performance of four OCT systems. The phantoms are based on 260-nm-diameter gold nanoshells, 400-nm-diameter iron oxide particles and 1.5-micron-diameter silica ...
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  Mentions: University of Maryland Pete H. Tomlins UK National Physical Laboratory
24. Quantitative analysis of low contrast detectability in optical coherence tomography
  
  Explore Conference Proceedings May 29 2014
  
  Optical coherence tomography (OCT) is a high resolution imaging technology that is rapidly being adopted as the standard of care for medical applications such as ocular and intravascular imaging. However, clinical translation has been hampered by the lack of standardized test methods for performance evaluation as well as consensus standards analogous to those that have been developed for established medical imaging modalities (e.g., ultrasound). In this study, we address low contrast detectability, specifically, the ability of systems to differentiate between regions exhibiting small differences in scattering coefficient. Based on standard test methods for established medical imaging modalities, we have ...
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  Mentions: University of Maryland FDA Yu Chen
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