1. Articles from Yalin Zheng

    1-20 of 20
    1. Quasi-tomography by free space line field spectral domain optical coherence reflectometry

      Quasi-tomography by free space line field spectral domain optical coherence reflectometry

      This paper reports the development of a new technique, free space line field spectral domain optical coherence reflectometry (LF-SD-OCR), which is able to produce tomographic like (quasi) images. Furthermore, the capabilities and cost benefits of the technique are demonstrated by constructing a handheld LF-SD-OCR device. For glossy paint systems and other suitable samples, the line field format produces quasi-tomographic (cross-sectional) imaging through the layers, with axial and lateral image resolutions of 1.3 µm and 40 µm respectively. From these, the clear coat thicknesses on the bonnet of cars were measured by graph search segmentation and maximum A-scan projection. In ...

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      Mentions: Yalin Zheng
    2. Differentiating Generic versus Branded Pharmaceutical Tablets Using Ultra-High-Resolution Optical Coherence Tomography

      Differentiating Generic versus Branded Pharmaceutical Tablets Using Ultra-High-Resolution Optical Coherence Tomography

      Optical coherence tomography (OCT) has recently been demonstrated as a powerful tool to image through pharmaceutical film coatings. Majority of the existing systems can, however, resolve film coatings for thickness greater than 10 µm. Here we report on an ultra-high-resolution (UHR) OCT system, with 1 µm axial and 1.6 µm lateral resolutions, which can resolve thin coatings at approximately 4 µm. We further demonstrate a novel application of the system for differentiating generic and branded suppliers of paracetamol tablets.

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      Mentions: Yalin Zheng
    3. Sub-surface imaging of soiled cotton fabric using full-field optical coherence tomography

      Sub-surface imaging of soiled cotton fabric using full-field optical coherence tomography

      In the laundry industry, colorimetry is a common way to evaluate the stain removal efficiency of detergents and cleaning products. For ease of visualization, the soiling agent is treated with a dye before measurement. However, it effectively measures the dye removal rather than stain removal, and it cannot provide depth-resolved information of the sample. In this study, we show that full-field (FF) optical coherence tomography (OCT) technique is capable of measuring the cleaning effect on cotton fabric by imaging the sub-surface features of fabric samples. We used a broadband light-emitting diode (LED) source to power the FF-OCT system that achieves ...

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      Mentions: Yalin Zheng
    4. Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures

      Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures

      There has been a lot of interest in accurately characterising corneal biomechanical properties under intraocular pressure (IOP) to help better understand ocular pathologies that are associated with elevated IOP. This study investigates the novel use of Line-Field Optical Coherence Tomography (LF-OCT) as an elastographic tool for accurately measuring mechanical properties of porcine corneas based on volumetric deformation following varying IOPs. A custom-built LF-OCT was used to measure geometrical and corneal surface displacement changes in porcine corneas under a range of IOPs, from 0–60 mmHg. Corneal thickness, elastic properties and hysteresis were calculated as a function of pressure. In addition ...

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      Mentions: Yalin Zheng
    5. Imaging of Corneal Neovascularization: Optical Coherence Tomography Angiography and Fluorescence Angiography

      Imaging of Corneal Neovascularization: Optical Coherence Tomography Angiography and Fluorescence Angiography

      Purpose : The purpose of this study was to compare optical coherence tomography angiography (OCTA) and indocyanine green angiography (ICGA) for the assessment of corneal neovascularization (CoNV). Methods : Patients with CoNV extending at least 3 mm into the cornea were included. All patients underwent corneal imaging at the same visit. Images were recorded using the AngioVue OCTA system (Optovue, Inc.) with the long corneal adaptor module (CAM-L). ICGA images were recorded with fluorescent filters using the Heidelberg system (HRA2 Scanning Laser Ophthalmoscope; Heidelberg Engineering). Images were graded for quality by two independent observers. Vessel parameters: area, number, diameter, branch and end ...

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    6. Deformation velocity imaging using optical coherence tomography and its applications to the cornea

      Deformation velocity imaging using optical coherence tomography and its applications to the cornea

      Optical coherence tomography (OCT) can monitor human donor corneas non-invasively during the de-swelling process following storage for corneal transplantation, but currently only resultant thickness as a function of time is extracted. To visualize and quantify the mechanism of de-swelling, we present a method exploiting the nanometer sensitivity of the Fourier phase in OCT data to image deformation velocities. The technique was demonstrated by non-invasively showing during de-swelling that osmotic flow through an intact epithelium is negligible and removing the endothelium approximately doubled the initial flow at that interface. The increased functional data further enabled the validation of a mathematical model ...

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      Mentions: Yalin Zheng
    7. Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Automotive coating systems are designed to protect vehicle bodies from corrosion and enhance their aesthetic value. The number, size and orientation of small metallic flakes in the base coat of the paint has a significant effect on the appearance of automotive bodies. It is important for quality assurance (QA) to be able to measure the properties of these small flakes, which are approximately 10 μm in radius, yet current QA techniques are limited to measuring layer thickness. We design and develop a time-domain (TD) full-field (FF) optical coherence tomography (OCT) system to scan automotive panels volumetrically, non-destructively and without contact ...

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    8. Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      The measurement of the thicknesses of layers is important for the quality assurance of industrial coating systems. Current measurement techniques only provide a limited amount of information. Here, we show that spectral domain Line Field (LF) Optical Coherence Tomography (OCT) is able to return to the user a cross sectional B-Scan image in a single shot with no mechanical moving parts. To reliably extract layer thicknesses from such images of automotive paint systems, we present an automatic graph search image segmentation algorithm. To show that the algorithm works independently of the OCT device, the measurements are repeated with a separate ...

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      Mentions: Yalin Zheng
    9. Volumetric Image Classification using Homogeneous Decomposition and Dictionary Learning: A Study Using Retinal Optical Coherence Tomography for Detecting Age-related Macular Degeneration

      Volumetric Image Classification using Homogeneous Decomposition and Dictionary Learning: A Study Using Retinal Optical Coherence Tomography for Detecting Age-related Macular Degeneration

      Three-Dimensional (3D) (volumetric) diagnostic imaging techniques are indispensable with respect to the diagnosis and management of many medical conditions. However there is a lack of automated diagnosis techniques to facilitate such 3D image analysis (although some support tools do exist). This paper proposes a novel framework for volumetric medical image classification founded on homogeneous decomposition and dictionary learning. In the proposed framework each image (volume) is recursively decomposed until homogeneous regions are arrived at. Each region is represented using a Histogram of Oriented Gradients (HOG) which is transformed into a set of feature vectors. The Gaussian Mixture Model (GMM) is ...

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    10. High resolution corneal and single pulse imaging with line field spectral domain optical coherence tomography

      High resolution corneal and single pulse imaging with line field spectral domain optical coherence tomography

      We report the development of a Spectral Domain Line Field Optical Coherence Tomography (LF-OCT) system, using a broad bandwidth and spatial coherent Super-Continuum (SC) source. With conventional quasi-Continuous Wave (CW) setup we achieve axial resolutions up to 2.1 μm in air and 3D volume imaging speeds up to 213 kA-Scan/s. Furthermore, we report the use of a single SC pulse, of 2 ns duration, to temporally gate an OCT B-Scan image of 70 A-Scans. This is the equivalent of 35 GA-Scans/s. We apply the CW setup for high resolution imaging of the fine structures of a human ...

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      Mentions: Yalin Zheng
    11. Nondestructive analysis of automotive paints with spectral domain optical coherence tomography

      Nondestructive analysis of automotive paints with spectral domain optical coherence tomography

      We have demonstrated for the first time, to our knowledge, the use of optical coherence tomography (OCT) as an analytical tool for nondestructively characterizing the individual paint layer thickness of multiple layered automotive paints. A graph-based segmentation method was used for automatic analysis of the thickness distribution for the top layers of solid color paints. The thicknesses measured with OCT were in good agreement with the optical microscope and ultrasonic techniques that are the current standard in the automobile industry. Because of its high axial resolution (5.5 μm), the OCT technique was shown to be able to resolve the ...

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      Mentions: Yalin Zheng
    12. The Application of Full-Field Optical Coherence Tomography on Evaluating Film Coating of Pharmaceutical Pellets

      The Application of Full-Field Optical Coherence Tomography on Evaluating Film Coating of Pharmaceutical Pellets

      This paper focuses on the application of full-field optical coherence tomography (FF-OCT) imaging on quantifying coating thickness and characterizing coating structures of two layer pharmaceutical pellets. This FF-OCT system used aninexpensive infrared light-emitting diode (LED) as the opticalsource and a commercial high speed complementary metal-oxidesemiconductor (CMOS) camera as the detector. A total volume of700 × 50 × 200 μm3 (x-y-z) were imaged by using the FF-OCTdevice. A high spatial resolution of 4.0 × 5.0 μm2 (axial × lateral)was achieved. In the cross-sectional image the internal structuredetails can be clearly observed and in particular particle-likefeatures can be clearly ...

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    13. Reconstruction of 3D surface maps from anterior segment optical coherence tomography images using graph theory and genetic algorithms

      Reconstruction of 3D surface maps from anterior segment optical coherence tomography images using graph theory and genetic algorithms

      Automatic segmentation of anterior segment optical coherence tomography images provides an important tool to aid management of ocular diseases. Previous studies have mainly focused on 2D segmentation of these images. A novel technique capable of producing 3D maps of the anterior segment is presented here. This method uses graph theory and dynamic programming with shape constraint to segment the anterior and posterior surfaces in individual 2D images. Genetic algorithms are then used to align 2D images to produce a full 3D representation of the anterior segment. In order to validate the results of the 2D segmentation comparison is made to ...

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    14. Standardization of choroidal thickness measurements using enhanced depth imaging optical coherence tomography

      Standardization of choroidal thickness measurements using enhanced depth imaging optical coherence tomography

      AIM: To describe and evaluate a standardized protocol for measuring the choroidal thickness (ChT) using enhanced depth imaging optical coherence tomography (EDI OCT). METHODS: Single 9 mm EDI OCT line scans across the fovea were used for this study. The protocol used in this study classified the EDI OCT images into four groups based on the appearance of the choroidal-scleral interface and suprachoroidal space. Two evaluation iterations of experiments were performed:first, the protocol was validated in a pilot study of 12 healthy eyes. Afterwards, the applicability of the protocol was tested in 82 eyes of patients with diabetes. Inter-observer ...

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    15. Fast segmentation of anterior segment optical coherence tomography images using graph cut

      Fast segmentation of anterior segment optical coherence tomography images using graph cut

      BackgroundOptical coherence tomography (OCT) is a non-invasive imaging system that can be used to obtain images of the anterior segment. Automatic segmentation of these images will enable them to be used to construct patient specific biomechanical models of the human eye. These models could be used to help with treatment planning and diagnosis of patients.MethodsA novel graph cut technique using regional and shape terms was developed. It was evaluated by segmenting 39 OCT images of the anterior segment. The results of this were compared with manual segmentation and a previously reported level set segmentation technique. Three different comparison techniques ...

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      Mentions: Yalin Zheng
    16. Classification of volumetric retinal images using overlapping decomposition and tree analysis

      Classification of volumetric retinal images using overlapping decomposition and tree analysis

      Methods for the classification of volumetric three-dimensional (3D) volumes (images) play an important role in the context of medical applications. In this paper, a dedicated tree based 3D representation is proposed that serves to directly capture 3D image features in such a way that classification techniques can be applied. More specifically an Overlapping Hierarchical Decomposition (OHD) technique is presented to generate a tree representation of a given 3D volume. The OHD method recursively decomposes a given 3D volume into sub-volumes forming a tree. Once the tree has been generated, a frequent sub-graph mining algorithm is applied to mine the tree ...

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      Mentions: Yalin Zheng
    17. Automated segmentation of the choroid in retinal optical coherence tomography images

      Automated segmentation of the choroid in retinal optical coherence tomography images

      The choroid is a tissue layer at the back of the eye, which can be imaged by optical coherence tomography (OCT). Choroidal thickness has been proven to be correlated to several ophthalmic diseases in several studies. In this paper we proposed a novel segmentation technique to address this challenge. This technique firstly automatically segments the inner boundary of the choroid using a two-stage fast active contour model. It secondly allows a real-time human-supervised automated segmentation on the outer boundary of the choroid. Dice similarity coefficient (DSC) was used to evaluate the agreement between manual annotation and our automated measurements on ...

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      Mentions: Yalin Zheng
    18. Automatic segmentation of anterior segment optical coherence tomography images

      Automatic segmentation of anterior segment optical coherence tomography images

      Optical coherence tomography (OCT) images can provide quantitative measurements of the eye’s entire anterior segment. A new technique founded on a newly proposed level set-based shape prior segmentation model has been developed for automatic segmentation of the cornea’s anterior and posterior boundaries. This technique comprises three major steps: removal of regions containing irrelevant structures and artifacts, estimation of the cornea’s location using a thresholding technique, and application of the new level set-based shape prior segmentation model to improve segmentation. The performance of our technique is compared to previously developed methods for analysis of the cornea in 33 ...

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    19. Volumetric image mining based on decomposition and graph analysis: An application to retinal optical coherence tomography

      Volumetric image mining based on decomposition and graph analysis: An application to retinal optical coherence tomography

      In this paper, we introduce a method for classifying volumetric images using a decomposition and graph analysis based method. Volume decomposition plays an important role in simplifying Three-Dimensional (3-D) volumes so as to enhance their analysis. Hierarchical decomposition techniques incrementally divide a given 3-D volume into sub-volumes according to some critical function and then (typically) represent the decomposition as a tree. The issue is the nature of the critical function which dictates when the decomposition should be stopped. Broadly the decomposition should be stopped whenever homogeneous sub-volumes are reached. The question is how we define homogeneity in this context. In ...

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      Mentions: Yalin Zheng
    20. Computerized Assessment of Intraretinal and Subretinal Fluid Regions in Spectral-Domain Optical Coherence Tomography Images of the Retina

      Computerized Assessment of Intraretinal and Subretinal Fluid Regions in Spectral-Domain Optical Coherence Tomography Images of the Retina

      Purpose To evaluate a new computerized segmentation technique for the quantification of intraretinal and subretinal fluid in spectral-domain optical coherence tomography (SD OCT) images of the retina. Design Prospective, cross-sectional study. Methods Thirty-seven B-scan images of 37 patients with exudative age-related macular degeneration were chosen randomly from SD OCT volume scans (1 per volume scan). All hyporeflective areas in the image first were segmented automatically as candidate regions by the program. Researchers who were masked to the candidate region information selected each fluid region from the original image using a single mouse click. The program then delineated the boundary of ...

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      Mentions: Yalin Zheng
    1-20 of 20
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  2. Topics in the News

    1. (16 articles) Yalin Zheng
    2. (2 articles) Wenzhou Medical College
    3. (1 articles) University College London
    4. (1 articles) Meixiao Shen
    5. (1 articles) Optovue
    6. (1 articles) Heidelberg Engineering
    7. (1 articles) Medical University of Vienna
    8. (1 articles) Harbin Medical University
    9. (1 articles) Université Pierre et Marie Curie
    10. (1 articles) University of Erlangen
    11. (1 articles) Wolfgang Drexler
    12. (1 articles) Adrian G. Podoleanu
    13. (1 articles) Mengyang Liu
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    Computerized Assessment of Intraretinal and Subretinal Fluid Regions in Spectral-Domain Optical Coherence Tomography Images of the Retina Volumetric image mining based on decomposition and graph analysis: An application to retinal optical coherence tomography Automatic segmentation of anterior segment optical coherence tomography images Automated segmentation of the choroid in retinal optical coherence tomography images Classification of volumetric retinal images using overlapping decomposition and tree analysis Standardization of choroidal thickness measurements using enhanced depth imaging optical coherence tomography Reconstruction of 3D surface maps from anterior segment optical coherence tomography images using graph theory and genetic algorithms The Application of Full-Field Optical Coherence Tomography on Evaluating Film Coating of Pharmaceutical Pellets Nondestructive analysis of automotive paints with spectral domain optical coherence tomography Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation Changes in the Retinal Microvasculature Measured Using Optical Coherence Tomography Angiography According to Age Direct en-face, speckle-reduced images using angular-compounded Master-Slave optical coherence tomography