Jiarui Yang

Choroidal morphologic and vascular features in patients with unilateral idiopathic epiretinal membranes: An optical coherence tomography analysis integrated with assessment of retinal layers

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Introduction: Integrated analysis of retinal and choroidal morphologic and vascular features is urgently needed to examine whether and how these two elements interact with each other, thus contributing to visual impairment in patients with idiopathic epiretinal membranes (iERMs). Methods: An observational retrospective study consisting of 181 patients diagnosed with unilateral iERM between August 2019 and July 2022 was carried out at Peking University Third Hospital. All patients underwent a standardized set of ophthalmologic examinations, including EDI-OCT and OCTA scanning, and were subsequently categorized into four stages according to current classification schemes based on their OCT findings. Altogether, 15 qualitative and quantitative parameters of both the retina (full-layer, inner and outer layers) and choroid were identified. Results: The results revealed variations in the choroidal vascularity index (CVI) among different stages of iERMs (p < 0.001) for the first t...

Volumetric characterization of microvasculature in ex vivo human brain samples by serial sectioning optical coherence tomography

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Objective: Serial sectioning optical coherence tomography (OCT) enables distortion-free volumetric reconstruction of several cubic centimeters of human brain samples. We aimed to identify anatomical features of the ex vivo human brain, such as intraparenchymal blood vessels and axonal fiber bundles, from the OCT data in 3D, using intrinsic optical contrast. Methods: We developed an automatic processing pipeline to enable characterization of the intraparenchymal microvascular network in human brain samples. Results: We demonstrated the automatic extraction of the vessels down to a 20 m in diameter using a filtering strategy followed by a graphing representation and characterization of the geometrical properties of microvascular network in 3D. We also showed the ability to extend this processing strategy to extract axonal fiber bundles from the volumetric OCT image. Conclusion: This method provides a viable tool for quantitative characterization of volumetric microvascular network as ...

CVIS: Automated OCT-scan-based software application for the measurements of choroidal vascularity index and choroidal thickness

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Purpose: To develop an automated image recognition software for the objective quantification of choroidal vascularity index (CVI) and choroidal thickness (CT) at different choroidal locations on images obtained from enhanced depth imaging optical coherence tomography (EDI-OCT), and to validate its reliability and investigate the difference and correlation between measurements made by manual and software. Methods: A total of 390 EDI-OCT scans, captured from 130 eligible emmetropic or myopic subjects, were categorized into four grades in terms of their accessibility to identify the choroidal-scleral interface (CSI) and were further assessed for CT and CVI at five locations (subfoveal, nasal, temporal, superior and inferior) by the newly developed Choroidal Vascularity Index Software (CVIS) and three ophthalmologists. Choroidal parameters acquired from CVIS were evaluated for its reliability and correlation with ocular factors, in comparison to manual measurements. Distribution of diff...

Choroidal Morphologic and Vascular Features in Patients With Myopic Choroidal Neovascularization and Different Levels of Myopia Based on Image Binarization of Optical Coherence Tomography

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Purpose: To characterize the choroidal morphologic and vascular features in different levels of myopes and patients with myopic choroidal neovascularization (mCNV). Methods: A total of 148 subjects were enrolled in this cross-sectional study, including 78 low-to-moderate myopes (LMM), 53 high myopes (HM), and 17 high myopic patients with mCNV. Ocular biometrics were measured using an optical low-coherence reflectometry device. Retinal and choroidal imaging was performed using enhanced depth imaging (EDI) spectral domain optical coherence tomography (OCT). Retinal parameters including retinal thickness and retinal volume were obtained from a built-in software. Binarization technique was adopted to investigate choroidal parameters including choroidal thickness (CT), vascular area, stromal area, and choroidal vascularity index (CVI). Choroidal parameters were measured at five locations to cover as much area of choroid as possible, and their patterns of distribution were further analyze...

Scalable mapping of myelin and neuron density in the human brain with micrometer resolution

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Optical coherence tomography (OCT) is an emerging 3D imaging technique that allows quantification of intrinsic optical properties such as scattering coefficient and back-scattering coefficient, and has proved useful in distinguishing delicate microstructures in the human brain. The origins of scattering in brain tissues are contributed by the myelin content, neuron size and density primarily; however, no quantitative relationships between them have been reported, which hampers the use of OCT in fundamental studies of architectonic areas in the human brain and the pathological evaluations of diseases. Here, we built a generalized linear model based on Mie scattering theory that quantitatively links tissue scattering to myelin content and neuron density in the human brain. We report a strong linear relationship between scattering coefficient and the myelin content that is retained across different regions of the brain. Neuronal cell body turns out to be a secondary contribution to the...

Ellipsoid Zone and External Limiting Membrane-Related Parameters on Spectral Domain-Optical Coherence Tomography and Their Relationships With Visual Prognosis After Successful Macular Hole Surgery

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Purpose: To compare structural diameters of the ellipsoid zone (EZ) and external limiting membrane (ELM) bands on spectral domain-optical coherence tomography (SD-OCT) images between vision-improved (group A) and vision-unimproved (group B) patients, and investigate the connection between these parameters and visual prognosis. Materials and Methods: Forty-five eyes of 43 patients with idiopathic full-thickness macular hole closed after vitrectomy were retrospectively reviewed. Best-corrected visual acuity (BCVA) and SD-OCT were conducted preoperatively and at 1 week, 1 month and 6 months postoperatively. Structural and functional parameters were then measured using ImageJ software. Results: Among structural and functional parameters, the relative reflectivity of EZ and the ratio of continuous ELM and EZ in group A were significantly higher than in group B from the 1-month postoperative visit. At the 6-month follow-up, the diameter of EZ disruption in group A was significantly smalle...

Scalable mapping of myelin and neuron density in the human brain with micrometer resolution

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Optical Coherence Tomography (OCT) is an emerging 3D imaging technique that allows quantification of intrinsic optical properties such as scattering coefficient and back-scattering coefficient, and has proved useful in distinguishing delicate microstructures in the human brain. The origins of scattering in brain tissues are contributed by the myelin content, neuron size and density primarily; however, no quantitative relationships between them have been reported, which hampers the use of OCT in fundamental studies of architectonic areas in the human brain and the pathological evaluations of diseases. To date, histology remains the golden standard, which is prone to errors and can only work on a small number of subjects. Here, we demonstrate a novel method that uses serial sectioning OCT to quantitatively measure myelin content and neuron density in the human brain. We found that the scattering coefficient possesses a strong linear relationship with the myelin content across differen...

Measuring myelin content and cell density in the human brain using optical coherence tomography

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Serial Sectioning Optical Coherence Tomography(serial sectioning OCT) has been widely used to investigate the structural and pathological features of brain samples. OCT is an optical imaging technique that provides both the 3D structure of the tissue as well as the optical properties including the scattering coefficient (μ s ) and back-scattering coefficient (μ b ). Serial sectioning OCT allows the reconstruction of distortion-free volumetric images at high contrast and high resolution, which has proven to be useful for the detection of cancerous tissue boundaries, visualizing 3D vascular structures and measuring neuron density. The tissue optical properties extracted from the OCT depth profile has been shown to be related to myelin content and neuron density. However, no quantitative correlation of the tissue optical properties with myelin content and neuron density has been reported. Establishing a quantitative relationship will potentially benefit the segmentation of anatom...

Improving the characterization of ex vivo human brain optical properties using high numerical aperture optical coherence tomography by spatially constraining the confocal parameters

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Significance: The optical properties of biological samples provide information about the structural characteristics of the tissue and any changes arising from pathological conditions. Optical coherence tomography (OCT) has proven to be capable of extracting tissue's optical properties using a model that combines the exponential decay due to tissue scattering and the axial point spread function that arises from the confocal nature of the detection system, particularly for higher numerical aperture (NA) measurements. A weakness in estimating the optical properties is the inter-parameter cross-talk between tissue scattering and the confocal parameters defined by the Rayleigh range and the focus depth. Aim: In this study, we develop a systematic method to improve the characterization of optical properties with high-NA OCT. Approach: We developed a method that spatially parameterizes the confocal parameters in a previously established model for estimating the optical properties from the ...

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