1. Articles from Lei Zhang

    1-8 of 8
    1. Calibration-free time-stretch optical coherence tomography with large imaging depth

      Calibration-free time-stretch optical coherence tomography with large imaging depth

      We demonstrate a calibration-free time-stretch optical coherence tomography (TS-OCT), based on an optical higher order dispersion compensation scheme, which substitutes the digital calibration with optical dispersion compensation. As a result, the acquired raw data can directly perform the Fourier transform, and data processing time is greatly reduced by 82%, compared with the digital calibration. Moreover, because of the high-sensitivity and calibration-free characteristics, the high-order dispersion compensation-based TS-OCT can increase sensitivity roll-off by 2.6 times to 6.91 mm/dB and effective imaging depth by 14.2% to 16 mm. The in vivo biological tissue imaging has been demonstrated, with ...

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    2. 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 pathological changes. In the present study, we applied vnOCT in an animal model of glaucoma (dexamethasone-induced ocular hypertension mouse) and tested the capabilities of four optical markers, VN ratio, peripapillary ...

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    3. 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 submitted for histologic diagnosis. Lesions were categorized as malignant, premalignant (with dysplasia) or benign. ISOCT and 2P-AF findings were compared between categories. Results : Fourteen specimens from 13 patients were collected ...

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    4. Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Purpose . To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF) underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods . Twenty participants (4 males and 16 females, 23.0 ± 3.7 years) were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral ...

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    5. Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing

      Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing

      Bioresorbable vascular scaffolds are new-generation stents that reduce the risk of intimal hyperplasia and late stent thrombosis. Intravascular optical coherence tomography is an important technique to evaluate images about struts. Analyzing strut status, such as apposition and malapposition, is important for the follow-up treatment of patients. Traditionally, it has taken up to 8 hours to manually analyze the strut status. In this study, a new method is presented to detect and quantify struts automatically. Ten pullback runs containing 7720 struts were acquired to validate the algorithm. For apposed/malapposed stent struts, the sensitivity of the method was 93.0% and ...

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    6. Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Multi-modal three dimensional (3D) optical imaging combining both structural sensitivity and molecular specificity is highly desirable in biomedical research. In this paper, we present a method termed oblique scanning laser microscopy (OSLM) to combine optical coherence tomography (OCT), for simultaneously volumetric structural and molecular imaging with cellular resolution in all three dimensions. Conventional 3D laser scanning fluorescence microscopy requires repeated optical sectioning to create z-stacks in depth. Here, the use of an obliquely scanning laser eliminates the z-stacking process, then allows highly efficient 3D OCT and fluorescence imaging by using only one raster scan. The current setup provides ~3.6 ...

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    7. Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography

      Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography

      Abstract Purpose  To investigate the earliest histological changes of the retina after laser treatment of diabetic retinopathy by using Spectral domain optical coherence tomography (SD-OCT, Heidelberg Engineering, Heidelberg, Germany). Methods  This study examined 320 laser burns from 16 eyes of 12 patients with early severe non-proliferative diabetic retinopathy (NPDR) that underwent laser photocoagulation according to the protocol which the Early Treatment Diabetic Retinopathy Study (ETDRS) recommended. SD-OCT scan was performed before the laser treatment, then 1 hour, 24 hours, 48 hours, 72 hours and 1 week after treatment. The main outcome measure was thickness change in outer retina (OR) in ...

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    8. Ultra-broadband light source for optical coherence tomography by fiber matching

      In this paper, an ultra-broadband all fiber light source for optical coherence tomography was obtained. This light source was obtained by supercontinuum (SC) generated in matched fibers with different characteristics. It was showed that the spectrum quality was affected by dispersion and nonlinear characteristics of the fiber pumped firstly. SC spectrum flatness on the short wavelength side of pumping wavelength was affected by characteristic of the fiber pumped secondly. Dispersion shifted fiber (DSF) was connected after highly nonlinear fiber (HNLF) to optimize spectral shape. Widely broadened SC spectrum was generated in the combination of 120m HNLF+4.5km DSF+2km ...
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    1-8 of 8
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  2. Topics in the News

    1. (3 articles) Boston University
    2. (3 articles) Ji Yi
    3. (1 articles) Tianjin University
    4. (1 articles) Wenzhou Medical College
    5. (1 articles) Meixiao Shen
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    Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model Calibration-free time-stretch optical coherence tomography with large imaging depth Measurement of the Shrinkage of Natural and Simulated Lesions on Root Surfaces using CP-OCT Optic-Net: A Novel Convolutional Neural Network for Diagnosis of Retinal Diseases from Optical Tomography Images Double layer sign: A new optical coherence tomography finding in active tubercular serpiginous-like choroiditis to monitor activity Influence of Epiretinal Membranes on the Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography in Glaucoma High signal-to-noise ratio reconstruction of low bit-depth optical coherence tomography using deep learning