1. Articles from Yali Jia

    1-24 of 88 1 2 3 4 »
    1. Signal strength reduction effects in optical coherence tomographic angiography

      Signal strength reduction effects in optical coherence tomographic angiography

      Objective To elucidate the relationship between vessel density (VD) measurements and signal strength in optical coherence tomography angiography (OCTA). Design Cross-sectional study. Subjects: Healthy volunteers. Methods OCTA images obtained from healthy volunteers were analyzed to demonstrate the relationship between signal strength index (SSI) and VD. Experiments were performed to determine the effects of signal strength reduction on VD measurements on the Optovue/AngioVue and Cirrus/AngioPlex OCTA systems. Signal strength reduction was generated by either neutral density filters (NDF) or defocus. Main Outcome Measures Regression analysis of signal strength effects on VD. Results VD decreased linearly with signal strength with ...

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    2. Maximum value projection produces better en face OCT angiograms than mean value projection

      Maximum value projection produces better en face OCT angiograms than mean value projection

      Optical coherence tomography angiography (OCTA) images rely on en face data projections for both qualitative and quantitative interpretation. Both maximum value and mean value projections are commonly used, and many researchers consider them essentially interchangeable approaches. On the contrary, we find that maximum value projection achieves a consistently higher signal-to-noise ratio and higher image contrast across multiple vascular layers, in both healthy eyes and for each disease examined.

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    3. Systems and methods for automated segmentation of retinal fluid in optical coherence tomography

      Systems and methods for automated segmentation of retinal fluid in optical coherence tomography

      Disclosed herein are methods and systems for the identification and characterization of fluid accumulation in the retina using OCT imaging. The disclosed methods and systems are directed to the automated segmentation of retinal fluid using 2D or 3D structural OCT scan images. Approaches for visualization and quantification of both intraretinal and subretinal fluid are presented. Methods are also disclosed for using OCT angiography data to improve the quality of retinal fluid segmentation, and to provide combined visualization of fluid accumulation and retinal vasculature to inform clinical interpretation of results.

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    4. Detection of Non-exudative Choroidal Neovascularization and Progression to Exudative Choroidal Neovascularization Using Optical Coherence Tomography Angiography

      Detection of Non-exudative Choroidal Neovascularization and Progression to Exudative Choroidal Neovascularization Using Optical Coherence Tomography Angiography

      Objective To detect non-exudative choroidal neovascularization (CNV) in age-related macular degeneration with optical coherence tomography angiography (OCTA) and determine risk of developing exudative CNV compared to eyes without non-exudative CNV. Design Prospective longitudinal observational study Participants Consecutive patients with drusen and pigmentary changes in the study eye and exudative neovascular AMD in the fellow eye. Methods Study participants underwent spectral domain OCTA (AngioVue, Optovue, Inc), clinical exam, and structural OCT at baseline and six-month intervals for two years. OCTA images were exported for custom processing to remove projection artifact and calculate CNV vessel area. Main Outcome Rate of developing exudation ...

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    5. Real-time cross-sectional and en face OCT angiography guiding high-quality scan acquisition

      Real-time cross-sectional and en face OCT angiography guiding high-quality scan acquisition

      Defocusing, vignetting, and bulk motion degrade the image quality of optical coherence tomography angiography (OCTA) more significantly than structural OCT. The assessment of focus, alignment conditions, and stability of imaging subjects in commercially available OCTA systems are currently based on OCT signal quality alone, without knowledge of OCTA signal quality. This results in low yield rates for further quantification. In this Letter, we developed a novel OCTA platform based on a graphics processing unit (GPU) for a real-time, high refresh rate, B-san-by-B-scan split-spectrum amplitude-decorrelation angiography. The GPU provides a real-time display of both cross-sectional and en face images to assist ...

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    6. DETECTION OF CLINICALLY UNSUSPECTED RETINAL NEOVASCULARIZATION WITH WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      DETECTION OF CLINICALLY UNSUSPECTED RETINAL NEOVASCULARIZATION WITH WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To evaluate wide-field optical coherence tomography angiography (OCTA) for detection of clinically unsuspected neovascularization (NV) in diabetic retinopathy (DR). Methods: This prospective observational single-center study included adult patients with a clinical diagnosis of nonproliferative DR. Participants underwent a clinical examination, standard 7-field color photography, and OCTA with commercial and prototype swept-source devices. The wide-field OCTA was achieved by montaging five 6 × 10-mm scans from a prototype device into a 25 × 10-mm image and three 6 × 6-mm scans from a commercial device into a 15 × 6-mm image. A masked grader determined the retinopathy severity from color photographs. Two trained readers ...

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    7. Automated detection of shadow artifacts in optical coherence tomography angiography

      Automated detection of shadow artifacts in optical coherence tomography angiography

      Frequently, when imaging retinal vasculature with optical coherence tomography angiography (OCTA) in diseased eyes, there are unavoidable obstacles to the propagation of light such as vitreous floaters or the pupil boundary. These obstacles can block the optical coherence tomography (OCT) beam and impede the visualization of the underlying retinal microcirculation. Detecting these shadow artifacts is especially important in the quantification of metrics that assess retinal disease progression because they might masquerade as regional perfusion loss. In this work, we present an algorithm to identify shadowed areas in OCTA of healthy subjects as well as patients with diabetic retinopathy, uveitis and ...

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    8. Automated phase unwrapping in Doppler optical coherence tomography

      Automated phase unwrapping in Doppler optical coherence tomography

      Phase wrapping is a crucial issue in Doppler optical coherence tomography (OCT) and restricts its automatic implementation for clinical applications that quantify total retinal blood flow. We propose an automated phase-unwrapping technique that takes advantage of the parabolic profile of blood flow velocity in vessels. Instead of inspecting the phase shift manually, the algorithm calculates the gradient magnitude of the phase shift on the cross-sectional image and automatically detects the presence of phase wrapping. The voxels affected by phase wrapping are corrected according to the determined flow direction adjacent to the vessel walls. We validated this technique in the rodent ...

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    9. Rodent retinal circulation organization and oxygen metabolism revealed by visible-light optical coherence tomography

      Rodent retinal circulation organization and oxygen metabolism revealed by visible-light optical coherence tomography

      Visible light optical coherence tomography (vis-OCT) is an emerging label-free and high-resolution 3-dimensional imaging technique that can provide retinal oximetry, angiography, and flowmetry in one modality. In this paper, we studied the organization of the arterial and venous retinal circulation in rats using vis-OCT. Arterioles were found predominantly in the superficial vascular plexus whereas veins tended to drain capillaries from the deep capillary plexus. After that, we determined the oxygen metabolic rate supported by retinal microcirculation by combining retinal vessel oxygen saturation and blood flow measurements. The ability to visualize and monitor retinal circulation organization and oxygen metabolism by vis-OCT ...

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    10. Quantitative evaluation of retinal artery occlusion using optical coherence tomography angiography: A case report

      Quantitative evaluation of retinal artery occlusion using optical coherence tomography angiography: A case report

      Rationale: Retinal artery occlusion (RAO) results in painless, catastrophic vision loss in a period of seconds. Optical coherence tomography angiography (OCTA) can image retinal microcirculation, which is helpful to evaluate treatment response during the follow-up period. Using a single case with central RAO, we report its retinal perfusion changes before and after treatment using OCTA. Patient concerns: A 36-year-old Chinese man came to our clinic with a sudden, painless loss of vision (hand motion) in his left eye. A vasodilator (nicotinic acid) was used as the primary treatment. OCTA imaging and a visual field examination were performed to assess the ...

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    11. Automated segmentation of retinal layer boundaries and capillary plexuses in wide-field optical coherence tomographic angiography

      Automated segmentation of retinal layer boundaries and capillary plexuses in wide-field optical coherence tomographic angiography

      Advances in the retinal layer segmentation of structural optical coherence tomography (OCT) images have allowed the separation of capillary plexuses in OCT angiography (OCTA). With the increased scanning speeds of OCT devices and wider field images (≥10 mm on fast-axis), greater retinal curvature and anatomic variations have introduced new challenges. In this study, we developed a novel automated method to segment seven retinal layer boundaries and two retinal plexuses in wide-field OCTA images. The algorithm was initialized by a series of points forming a guidance point array that estimates the location of retinal layer boundaries. A guided bidirectional graph search ...

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    12. Classification of Choroidal Neovascularization Using Projection-Resolved Optical Coherence Tomographic Angiography

      Classification of Choroidal Neovascularization Using Projection-Resolved Optical Coherence Tomographic Angiography

      Purpose : To evaluate if projection-resolved optical coherence tomographic angiography (PR-OCTA) reduces projection artifact with less attenuation of choroidal neovascularization (CNV) flow signal compared to conventional OCTA with slab subtraction. Methods : In this retrospective cross-sectional study, participants with subfoveal treatment-naïve CNV secondary to age-related macular degeneration underwent OCTA. Scans were exported for custom processing including manual segmentation as necessary, application of slab subtraction and PR-OCTA algorithm, and calculation of CNV vascular area and connectivity. CNV was classified as type 1, minimally type 2, or predominantly type 2 based on fluorescein angiography (FA) and OCT. Two masked retina specialists independently classified ...

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    13. Systems And Methods For REFLECTANCE-BASED PROJECTION-RESOLVED Optical Coherence Tomography Angiography

      Systems And Methods For REFLECTANCE-BASED PROJECTION-RESOLVED Optical Coherence Tomography Angiography

      Embodiments provide systems and methods associated with a reflectance-based projection-resolved (rbPR) optical coherence tomography angiography (OCTA) algorithm which uses optical coherence tomography (OCT) reflectance to enhance the flow signal and suppress the projection artifacts in 3-dimensional OCTA. rbPR improves the vascular connectivity and improved the discrimination of the deeper plexus angiograms in healthy eyes, compared to prior PR-OCTA method. Additionally, rbPR removes flow projection artifacts more completely from the outer retinal slab in the eyes with age-related macular degeneration, and preserves vascular integrity of the intermediate and deep capillary plexuses in the eyes with diabetic retinopathy. Additionally, the rbPR method ...

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    14. Deep learning for the segmentation of preserved photoreceptors on en face optical coherence tomography in two inherited retinal diseases

      Deep learning for the segmentation of preserved photoreceptors on en face optical coherence tomography in two inherited retinal diseases

      The objective quantification of photoreceptor loss in inherited retinal degenerations (IRD) is essential for measuring disease progression, and is now especially important with the growing number of clinical trials. Optical coherence tomography (OCT) is a non-invasive imaging technology widely used to recognize and quantify such anomalies. Here, we implement a versatile method based on a convolutional neural network to segment the regions of preserved photoreceptors in two different IRDs (choroideremia and retinitis pigmentosa) from OCT images. An excellent segmentation accuracy (~90%) was achieved for both IRDs. Due to the flexibility of this technique, it has potential to be extended to ...

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    15. Automated Quantification of Nonperfusion Areas in 3 Vascular Plexuses With Optical Coherence Tomography Angiography in Eyes of Patients With Diabetes

      Automated Quantification of Nonperfusion Areas in 3 Vascular Plexuses With Optical Coherence Tomography Angiography in Eyes of Patients With Diabetes

      Importance Diabetic retinopathy (DR) is a leading cause of vision loss that is managed primarily through qualitative clinical examination of the retina. Optical coherence tomography angiography (OCTA) may offer an objective and quantitative method of evaluating DR. Objective To quantify capillary nonperfusion in 3 vascular plexuses in the macula of eyes patients with diabetes of various retinopathy severity using projection-resolved OCTA (PR-OCTA). Design, Setting, and Participants Cross-sectional study at a tertiary academic center comprising 1 eye each from healthy control individuals and patients with diabetes at different severity stages of retinopathy. Data were acquired and analyzed between January 2015 and ...

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    16. Evaluation of Automatically Quantified Foveal Avascular Zone Metrics for Diagnosis of Diabetic Retinopathy Using Optical Coherence Tomography Angiography

      Evaluation of Automatically Quantified Foveal Avascular Zone Metrics for Diagnosis of Diabetic Retinopathy Using Optical Coherence Tomography Angiography

      Purpose : To describe an automated algorithm to quantify the foveal avascular zone (FAZ), using optical coherence tomography angiography (OCTA), and to compare its performance for diagnosis of diabetic retinopathy (DR) and association with best-corrected visual acuity (BCVA) to that of extrafoveal avascular area (EAA). Methods : We obtained 3 × 3-mm macular OCTA scans in diabetic patients with various levels of DR and healthy controls. An algorithm based on a generalized gradient vector flow (GGVF) snake model detected the FAZ, and metrics assessing FAZ size and irregularity were calculated. We compared the automated FAZ segmentation to manual delineation and tested the within-visit ...

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    17. Fast and robust standard-deviation-based method for bulk motion compensation in phase-based functional OCT

      Fast and robust standard-deviation-based method for bulk motion compensation in phase-based functional OCT

      Phase-based optical coherence tomography (OCT), such as OCT angiography (OCTA) and Doppler OCT, is sensitive to the confounding phase shift introduced by subject bulk motion. Traditional bulk motion compensation methods are limited by their accuracy and computing cost-effectiveness. In this Letter, to the best of our knowledge, we present a novel bulk motion compensation method for phase-based functional OCT. Bulk motion associated phase shift can be directly derived by solving its equation using a standard deviation of phase-based OCTA and Doppler OCT flow signals. This method was evaluated on rodent retinal images acquired by a prototype visible light OCT and ...

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    18. Automated spectroscopic retinal oximetry with visible-light optical coherence tomography

      Automated spectroscopic retinal oximetry with visible-light optical coherence tomography

      Accurate, quantitative assessment of retinal blood oxygen saturation ( sO 2 ) may provide a useful early indicator of pathophysiology in several ocular diseases. Here, with visible-light optical coherence tomography (OCT), we demonstrate an automated spectroscopic retinal oximetry algorithm to measure the sO 2 within the retinal arteries (A- sO 2 ) and veins (V- sO 2 ) in rats by automatically detecting the vascular posterior boundary on cross-sectional structural OCT. The algorithm was validated in vitro with flow phantoms and in vivo in rats by comparing the sO 2 results, respectively, to those obtained using a blood gas analyzer and pulse oximetry. We ...

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    19. Automated detection of preserved photoreceptor on optical coherence tomography in choroideremia based on machine learning

      Automated detection of preserved photoreceptor on optical coherence tomography in choroideremia based on machine learning

      Optical coherence tomography (OCT) can demonstrate early deterioration of the photoreceptor integrity caused by inherited retinal degeneration diseases (IRD). A machine learning method based on random forests was developed to automatically detect continuous areas of preserved ellipsoid zone structure (an easily recognizable part of the photoreceptors on OCT) in sixteen eyes of patients with choroideremia (a type of IRD). Pseudopodial extensions protruding from the preserved ellipsoid zone areas are detected separately by a local active contour routine. The algorithm is implemented on en face images with minimum segmentation requirements, only needing delineation of the Bruch's membrane, thus evading the ...

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    20. Polarization-multiplexed, dual-beam swept source optical coherence tomography angiography

      Polarization-multiplexed, dual-beam swept source optical coherence tomography angiography

      A polarization-multiplexed, dual-beam setup is proposed to expand the field of view for a swept source optical coherence tomography angiography (OCTA) system. This method used a Wollaston prism to split sample path light into two orthogonal-polarized beams. This allowed two beams to shine on the cornea at an angle separation of ~ 14 degrees, which led to a separation of ~ 4.2 mm on the retina. A 3-mm glass plate was inserted into one of the beam paths to set a constant path length difference between the two polarized beams so the interferogram from the two beams are coded at different ...

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    21. Automated detection of photoreceptor disruption in mild diabetic retinopathy on volumetric optical coherence tomography

      Automated detection of photoreceptor disruption in mild diabetic retinopathy on volumetric optical coherence tomography

      Diabetic retinopathy is a pathology where microvascular circulation abnormalities ultimately result in photoreceptor disruption and, consequently, permanent loss of vision. Here, we developed a method that automatically detects photoreceptor disruption in mild diabetic retinopathy by mapping ellipsoid zone reflectance abnormalities from en face optical coherence tomography images. The algorithm uses a fuzzy c-means scheme with a redefined membership function to assign a defect severity level on each pixel and generate a probability map of defect category affiliation. A novel scheme of unsupervised clustering optimization allows accurate detection of the affected area. The achieved accuracy, sensitivity and specificity were about 90 ...

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    22. OCT Angiography Changes in the 3 Parafoveal Retinal Plexuses in Response to Hyperoxia

      OCT Angiography Changes in the 3 Parafoveal Retinal Plexuses in Response to Hyperoxia

      Purpose Use projection-resolved OCT angiography to investigate the autoregulatory response in the 3 parafoveal retinal plexuses under hyperoxia. Design Prospective cohort study. Participants Nine eyes from 9 healthy participants. Methods One eye from each participant was scanned using a commercial spectral-domain OCT system. Two repeated macular scans (3 × 3 mm 2 ) were acquired at baseline and during oxygen breathing. The split-spectrum amplitude-decorrelation algorithm was used to detect blood flow. The projection-resolved algorithm was used to suppress projection artifacts and resolve blood flow in 3 distinct parafoveal plexuses. The Wilcoxon signed-rank test was used to compare baseline and hyperoxic parameters. The ...

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    23. Automated drusen detection in dry age-related macular degeneration by multiple-depth, en face optical coherence tomography

      Automated drusen detection in dry age-related macular degeneration by multiple-depth, en face optical coherence tomography

      We introduce a method to automatically detect drusen in dry age-related macular degeneration (AMD) from optical coherence tomography with minimum need for layer segmentation. The method is based on the en face detection of drusen areas in C-scans at certain distances above the Bruch’s membrane, circumventing the difficult task of pathologic retinal pigment epithelium segmentation. All types of drusen can be detected, including the challenging subretinal drusenoid deposits (pseudodrusen). The high sensitivity and accuracy demonstrated here shows its potential for detection of drusen onset in early AMD.

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    24. Projection-resolved optical coherence tomography angiography exhibiting early flow prior to clinically observed retinal angiomatous proliferation

      Projection-resolved optical coherence tomography angiography exhibiting early flow prior to clinically observed retinal angiomatous proliferation

      Purpose The purpose of this study is to analyze early retinal angiomatous proliferation (RAP) utilizing a novel imaging modality, Projection-Resolved Optical Coherence Tomography Angiography (PR-OCTA). Observations Five months prior to the diagnosis of a RAP lesion, cross-sectional PR-OCTA demonstrated flow in the outer retina contiguous with the deep retinal capillary plexus (DCP) and adjacent to a small pigment epithelial detachment. After development of a clinically visible RAP lesion, cross-sectional PR-OCTA demonstrated the RAP lesion connecting DCP and sub-retinal pigment epithelial neovascularization. Conclusions & Importance This is the first report of PR-OCTA demonstrating abnormal flow in the outer retina prior to the ...

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    1. (87 articles) Yali Jia
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