1. Ji Yi

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    1. Mentioned In 44 Articles

    2. Visible light optical coherence tomography angiography (vis-OCTA) facilitates local microvascular oximetry in the human retina

      Visible light optical coherence tomography angiography (vis-OCTA) facilitates local microvascular oximetry in the human retina
      We report herein the first visible light optical coherence tomography angiography (vis-OCTA) for human retinal imaging. Compared to the existing vis-OCT systems, we devised a spectrometer with a narrower bandwidth to increase the spectral power density for OCTA imaging, while retaining the major spectral contrast in the blood. We achieved a 100 kHz A-line rate, the fastest acquisition speed reported so far for human retinal vis-OCT. We rigorously optimized the ...
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    3. Special Section Guest Editorial: Advances in Retinal Imaging

      Special Section Guest Editorial: Advances in Retinal Imaging
      The guest editorial provides an introduction to the Special Section on Advanced Retinal Imaging: Instrumentation, Methods, and Applications. The retina is a peripheral part of the central nerve system (CNS) and shares many similarities with the cerebral cortex. They both have layered anatomy, the same types of functional elements and neurotransmitters, and similar vascular organization and blood-tissue barriers. With far fewer neuronal cell types and simpler anatomical structures, the retina ...
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    4. Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification

      Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification
      Measurement of blood oxygen saturation ( s O 2 ) by optical imaging oximetry provides invaluable insight into local tissue functions and metabolism. Despite different embodiments and modalities, all label-free optical-imaging oximetry techniques utilize the same principle of s O 2 -dependent spectral contrast from haemoglobin. Traditional approaches for quantifying s O 2 often rely on analytical models that are fitted by the spectral measurements. These approaches in practice suffer from uncertainties ...
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    5. Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model

      Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model
      The retina, as part of the central nervous system, has distinct anatomical and structural properties for its visual function. Light scattering spectroscopy, while widely used for tissue structural characterization and disease diagnosis, has been relatively unexplored in the living retina. Recently, we have developed a fiber-based visible and near-infrared optical coherence tomography system (vnOCT) for in vivo retinal imaging, to uniquely measure a spectroscopic marker (VN ratio) sensitive to nanoscale ...
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    6. Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence

      Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence
      Purpose : Advanced imaging is increasingly important in the diagnosis of ocular surface malignancy. Inverse spectroscopic optical coherence tomography (ISOCT) and two-photon autofluorescence microscopy (2P-AF) are emerging techniques capable of quantifying ultrastructural and metabolic changes, respectively. We aimed to detect malignancy in ocular surface lesions using ISOCT and 2P-AF. Methods : Portions of excised specimens from patients undergoing conjunctival biopsy at Boston Medical Center were imaged by ISOCT and/or 2P-AF, and ...
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    7. Quantitative quality-control metrics for in vivo oximetry in small vessels by visible light optical coherence tomography angiography

      Quantitative quality-control metrics for in vivo oximetry in small vessels by visible light optical coherence tomography angiography
      Biological functions rely on local microvasculature to deliver oxygen and nutrients and carry away metabolic waste. Alterations to local oxygenation levels are manifested in diseases including cancer, diabetes mellitus, etc. The ability to quantify oxygen saturation (sO 2 ) within microvasculature in vivo to assess local tissue oxygenation and metabolic function is highly sought after. Visible light optical coherence tomography (vis-OCT) angiography has shown promise in reaching this goal. However, achieving ...
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    8. Retinal blood flow reduction after panretinal photocoagulation in Type 2 diabetes mellitus: Doppler optical coherence tomography flowmeter pilot study

      Retinal blood flow reduction after panretinal photocoagulation in Type 2 diabetes mellitus: Doppler optical coherence tomography flowmeter pilot study
      ...graphy flowmeter pilot study. PLoS ONE 13(11): e0207288. https://doi.org/10.1371/journal.pone.0207288 Editor: Ji Yi, Boston Medical Center, Boston University School of Medicine, UNITED STATES Received: June 17, 2018; Acc...
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    9. Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography

      Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan inverse spectroscopic optical coherence tomography
      Measuring capillary oxygenation and the surrounding ultrastructure can allow one to monitor a microvascular niche and better understand crucial biological mechanisms. However, capillary oximetry and pericapillary ultrastructure are challenging to measure in vivo. Here, we demonstrate a novel optical imaging system, Dual-band Dual-scan Inverse Spectroscopic Optical Coherence Tomography (D2- ISOCT), that, for the first time, can simultaneously obtain the following metrics in vivo using endogenous contrast: (1) capillary-level oxygen saturation ...
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    10. Multimodal Volumetric Retinal Imaging by Oblique Scanning Laser Ophthalmoscopy (oSLO) and Optical Coherence Tomography (OCT)

      Multimodal Volumetric Retinal Imaging by Oblique Scanning Laser Ophthalmoscopy (oSLO) and Optical Coherence Tomography (OCT)
      While fluorescence imaging is widely used in ophthalmology, a large field of view (FOV) three-dimensional (3D) fluorescence retinal image is still a big challenge with the state-of-the-art retinal imaging modalities because they would require z-stacking to compile a volumetric dataset. Newer optical coherence tomography (OCT) and OCT angiography (OCTA) systems overcome these restrictions to provide three-dimensional (3D) anatomical and vascular images, but the dye-free nature of OCT cannot visualize leakage ...
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    11. Fiber-based visible and near infrared optical coherence tomography (vnOCT) enables quantitative elastic light scattering spectroscopy in human retina

      Fiber-based visible and near infrared optical coherence tomography (vnOCT) enables quantitative elastic light scattering spectroscopy in human retina
      Elastic light scattering spectroscopy (ELSS) has been proven a powerful method in measuring tissue structures with exquisite nanoscale sensitivity. However, ELSS contrast in the living human retina has been relatively underexplored, primarily due to the lack of imaging tools with a large spectral bandwidth. Here, we report a simple all fiber-based setup to implement dual-channel visible and near infrared (NIR) optical coherence tomography (vnOCT) for human retinal imaging, bridging over ...
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    12. Measurement of Flow‐Mediated Dilation of Mouse Femoral Artery in vivo by Optical Coherence Tomography

      Measurement of Flow‐Mediated Dilation of Mouse Femoral Artery in vivo by Optical Coherence Tomography
      Flow‐mediated vasodilation (FMD) is used for assessment of vascular endothelial function in humans as a predictor of cardiovascular events. It has been challenging to carry it on preclinical murine models due to the diminutive size of the femoral artery. Here, we present a new approach to accurately measure the blood velocity and femoral artery diameters of mice by acquiring Doppler optical coherence tomography (DOCT) and optical coherence tomography angiography ...
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      Mentions: Ji Yi
    13. In vivo broadband visible light optical coherence tomography probe enables inverse spectroscopic analysis

      In vivo broadband visible light optical coherence tomography probe enables inverse spectroscopic analysis
      We report the design and characterization of a 6 mm outer diameter pull-back circumferential scanning visible optical coherence tomography probe. The probes large visible bandwidth (500695 nm) allowed for inverse spectroscopic analysis and an axial resolution of 1.1 m 1.1m in tissue. We verify spectral imaging capabilities by measuring microsphere backscattering spectra and demonstrate in vivo spatial nanoscale characterization of tissue.
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    14. 1-15 of 44 1 2 3 »
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  2. About Ji Yi

    Ji Yi

    Ji Yi is an assistant professor of biomedical engineering and ophthalmology at Johns Hopkins University and Wilmer Eye institute. His specialty is ophthalmic imaging, and multimodal microscopy. He developed various imaging methods to characterize biological structures and functions. By applying those techniques, he demonstrated the detection of the earliest form of retinal diseases, and cancers.