1. Articles from Li Zhang

    1-14 of 14
    1. Automated framework for intraretinal cystoid macular edema segmentation in three-dimensional optical coherence tomography images with macular hole

      Automated framework for intraretinal cystoid macular edema segmentation in three-dimensional optical coherence tomography images with macular hole

      Cystoid macular edema (CME) and macular hole (MH) are the leading causes for visual loss in retinal diseases. The volume of the CMEs can be an accurate predictor for visual prognosis. This paper presents an automatic method to segment the CMEs from the abnormal retina with coexistence of MH in three-dimensional-optical coherence tomography images. The proposed framework consists of preprocessing and CMEs segmentation. The preprocessing part includes denoising, intraretinal layers segmentation and flattening, and MH and vessel silhouettes exclusion. In the CMEs segmentation, a three-step strategy is applied. First, an AdaBoost classifier trained with 57 features is employed to generate ...

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    2. Evaluating Efficacy of Aflibercept in Refractory Exudative Age-Related Macular Degeneration With OCT Segmentation Volumetric Analysis

      Evaluating Efficacy of Aflibercept in Refractory Exudative Age-Related Macular Degeneration With OCT Segmentation Volumetric Analysis

      BACKGROUND AND OBJECTIVE: To use automated segmentation software to analyze spectral-domain optical coherence tomography (SD-OCT) scans and evaluate the effectiveness of aflibercept (Eylea; Regeneron, Tarrytown, NY) in the treatment of patients with exudative age-related macular degeneration (AMD) refractory to other treatments. PATIENTS AND METHODS: Retrospective chart review of 16 patients refractory to bevacizumab (Avastin; Genentech, South San Francisco, CA)/ranibizumab (Lucentis; Genentech, San Francisco, CA) treatment was conducted. Visual acuity, central foveal thickness (CFT), maximum fluid height, pigment epithelial detachment (PED) volume, sub-retinal fluid (SRF) volume, fluid-free time interval, and adverse effects were evaluated. Automated segmentation analysis was used to ...

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    3. Choroidal thickness maps from spectral domain and swept source optical coherence tomography: algorithmic versus ground truth annotation

      Choroidal thickness maps from spectral domain and swept source optical coherence tomography: algorithmic versus ground truth annotation

      Background/aims The purpose of the study was to create a standardised protocol for choroidal thickness measurements and to determine whether choroidal thickness measurements made on images obtained by spectral domain optical coherence tomography (SD-OCT) and swept source (SS-) OCT from patients with healthy retina are interchangeable when performed manually or with an automatic algorithm. Methods 36 grid cell measurements for choroidal thickness for each volumetric scan were obtained, which were measured for SD-OCT and SS-OCT with two methods on 18 eyes of healthy volunteers. Manual segmentation by experienced retinal graders from the Vienna Reading Center and automated segmentation on ...

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    4. Clinical Characteristics and Prognosis of Peri-strut Low-intensity Area Detected by Optical Coherence Tomography

      Clinical Characteristics and Prognosis of Peri-strut Low-intensity Area Detected by Optical Coherence Tomography

      Background: Peri-strut low-intensity area (PLIA) is a typical image pattern of neointima detected by optical coherence tomography (OCT) after stent implantation. However, few studies evaluated the predictors and prognosis of the PLIA; therefore, we aimed to explore the genesis and prognosis of PLIA detected by OCT in this study. Methods: Patients presenting neointimal hyperplasia documented by OCT reexamination after percutaneous coronary intervention were prospectively included from 2009 to 2011. Peri-strut intensity was analyzed and classified into two patterns: Low-intensity and high-intensity. Clinical characteristics were analyzed to assess their contribution to peri-strut intensity patterns. Follow-up were performed in patients who did ...

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    5. Validity of Automated Choroidal Segmentation in SS-OCT and SD-OCT

      Validity of Automated Choroidal Segmentation in SS-OCT and SD-OCT

      Purpose. To evaluate the validity of a novel fully automated three-dimensional (3D) method capable of segmenting the choroid from two different optical coherence tomography scanners: swept-source OCT (SS-OCT) and spectral-domain OCT (SD-OCT). Methods. One hundred eight subjects were imaged using SS-OCT and SD-OCT. A 3D method was used to segment the choroid and quantify the choroidal thickness along each A-scan. The segmented choroidal posterior boundary was evaluated by comparing to manual segmentation. Differences were assessed to test the agreement between segmentation results of the same subject. Choroidal thickness was defined as the Euclidian distance between Bruch's membrane and the ...

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    6. Fast and memory-efficient LOGISMOS graph search for intraretinal layer segmentation of 3D macular OCT scans

      Fast and memory-efficient LOGISMOS graph search for intraretinal layer segmentation of 3D macular OCT scans

      Image segmentation is important for quantitative analysis of medical image data. Recently, our research group has introduced a 3-D graph search method which can simultaneously segment optimal interacting surfaces with respect to the cost function in volumetric images. Although it provides excellent segmentation accuracy, it is computationally demanding (both CPU and memory) to simultaneously segment multiple surfaces from large volumetric images. Therefore, we propose a new, fast, and memory-efficient graph search method for intraretinal layer segmentation of 3-D macular optical coherence tomograpy (OCT) scans. The key idea is to reduce the size of a graph by combining the nodes with ...

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    7. Three-dimensional automated choroidal volume assessment on standard spectral-domain optical coherence tomography and correlation with the level of diabetic macular edema

      Three-dimensional automated choroidal volume assessment on standard spectral-domain optical coherence tomography and correlation with the level of diabetic macular edema

      Purpose To measure choroidal thickness on spectral-domain optical coherence tomography (SD-OCT) images using automated algorithms and to correlate choroidal pathology with retinal changes due to diabetic macular edema (DME). Design Post-hoc analysis of multicenter clinical trial baseline data. Methods SD-OCT raster scans/fluorescein angiograms were obtained from 284 treatment naïve eyes of 142 patients with clinically significant DME and from 20 controls. Three-dimensional (3D) SD-OCT images were evaluated by a certified independent reading center analyzing retinal changes associated with diabetic retinopathy. Choroidal thicknesses were analyzed using a fully automated algorithm. Angiograms were assessed manually. Multiple endpoint correction according to ...

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    8. Quantifying disrupted outer retina-subretinal layer in SD-OCT images in choroidal neovascularization

      Quantifying disrupted outer retina-subretinal layer in SD-OCT images in choroidal neovascularization

      Purpose: To report a fully automated method to identify and quantify the thickness of the outer retinal-subretinal (ORSR) layer from clinical spectral-domain optical coherence tomography (SD-OCT) scans of choroidal neovascularization (CNV) due to exudative age-related macular degeneration (e-AMD). Methods: 23 Subjects with CNV met eligibility. Volumetric SD-OCT scans of 23 eyes were obtained (Zeiss Cirrus, 200×200×1024 voxels). In a subset of eyes, scans were repeated. OCT volumes were analyzed using our standard parameters and using a 3D graph-search approach with an adaptive cost function. A retinal specialist graded the segmentation as generally accurate, local segmentation inaccuracies, or failure ...

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    9. Three-dimensional segmentation of fluid-associated abnormalities in retinal OCT: probability constrained graph-search-graph-cut.

      Three-dimensional segmentation of fluid-associated abnormalities in retinal OCT: probability constrained graph-search-graph-cut.

      An automated method is reported for segmenting 3-D fluid-associated abnormalities in the retina, so-called symptomatic exudate-associated derangements (SEAD), from 3-D OCT retinal images of subjects suffering from exudative age-related macular degeneration. In the first stage of a two-stage approach, retinal layers are segmented, candidate SEAD regions identified, and the retinal OCT image is flattened using a candidate-SEAD aware approach. In the second stage, a probability constrained combined graph search-graph cut method refines the candidate SEADs by integrating the candidate volumes into the graph cut cost function as probability constraints. The proposed method was evaluated on 15 spectral domain OCT images ...

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    10. Quantification of External Limiting Membrane Disruption Caused by Diabetic Macular Edema from SD-OCT

      Quantification of External Limiting Membrane Disruption Caused by Diabetic Macular Edema from SD-OCT

      Purpose. Disruption of external limiting membrane (ELM) integrity on spectral-domain optical coherence tomography (SD-OCT) is associated with lower visual acuity outcomes in patients suffering from diabetic macular edema (DME). However, no automated methods to detect ELM and/or determine its integrity from SD-OCT exist. Methods. Sixteen subjects diagnosed with clinically significant DME (CSME) were included and underwent macula-centered SD-OCT (512 × 19 × 496 voxels). Sixteen subjects without retinal thickening and normal acuity were also scanned (200 × 200 × 1024 voxels). Automated quantification of ELM disruption was achieved as follows. First, 11 surfaces were automatically segmented using our standard 3-D graph-search approach, and ...

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    11. Automated segmentation of the choroid from clinical SD-OCT

      Automated segmentation of the choroid from clinical SD-OCT

      Purpose: To develop and evaluate a fully automated three-dimensional method for segmentation of the choroidal vessels, quantification of choroidal vasculature thickness and choriocapillaris-equivalent thickness of the macula, and evaluate repeat variability in normal subjects using standard clinically available SD-OCT. Methods: normal subjects (24) were imaged twice, using clinically available, 3D spectral-domain optical coherence tomography (Cirrus, Carl-Zeiss, Dublin, CA). A novel, fully-automated three-dimensional method was used to segment and visualize the choroidal vasculature in macular scans. Local choroidal vasculature and choriocapillaris-equivalent thicknesses were determined. Reproducibility on repeat imaging was analyzed using overlapping rates, Dice coefficient, and Root Mean Square Coefficient of ...

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    12. Cotton-Wool Spot and Optical Coherence Tomography of a Retinal Nerve Fiber Layer Defect

      Cotton-Wool Spot and Optical Coherence Tomography of a Retinal Nerve Fiber Layer Defect

      A 53-year-old woman with severe arterial hypertension was concerned about flashes and a shadow in her left eye. Perimetry revealed an arc-shaped visual field defect in the superior hemisphere. Ophthalmoscopy showed a large cotton-wool spot inferior of the optic disc (Figure 1, above). Optical coherence tomography showed an edema of the retinal nerve fiber layer in the area of the cotton-wool spot. One year later, perimetry was unchanged. On ophthalmoscopy, an inferior wedge-shaped defect of the retinal nerve fiber layer was detected (Figure 2A, right, white arrows), while the cotton-wool spot completely vanished. Optical coherence tomography revealed a marked reduction ...

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    13. Evaluation of long-term follow-up with neointimal coverage and stent apposition after sirolimus-eluting stent implantation by optical coherence tomography

      Evaluation of long-term follow-up with neointimal coverage and stent apposition after sirolimus-eluting stent implantation by optical coherence tomography

      Background Late stent thrombosis related to delayed endothelialization is a major concern after drug-eluting stent (DES) implantation. The long-term vascular response towards DES implantation remains unclear. Optical coherence tomography (OCT) is a high resolution imaging modality which provides new opportunities for evaluating neointimal coverage and stent strut apposition after stent implantation. Methods Fifty two patients who accepted 64 sirolimus-eluting stents (SESs, Cypher Select) were enrolled in the study. The OCT procedure was performed in 20 patients at 12 months (group 1), 17 patients at 24 months (group 2), and 15 patients at 48 months (group 3) after SESs implantation, respectively ...

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    14. Imaging port wine stains by fiber optical coherence tomography

      Imaging port wine stains by fiber optical coherence tomography

      We develop a fiber optical coherence tomography (OCT) system in the clinical utility of imaging port wine stains (PWS). We use our OCT system on 41 patients with PWS to document the difference between PWS skin and contralateral normal skin. The system, which operates at 4 frames/s with axial and transverse resolutions of 10 and 9 µm, respectively, in the skin tissue, can clearly distinguish the dilated dermal blood vessels from normal tissue. We present OCT images of patients with PWS and normal human skin. We obtain the structural parameters, including epidermal thickness and diameter and depth of dilated ...

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    1-14 of 14
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  2. Topics in the News

    1. (9 articles) University of Iowa
    2. (9 articles) Milan Sonka
    3. (9 articles) Michael D. Abràmoff
    4. (5 articles) Kyungmoo Lee
    5. (2 articles) Medical University of Vienna
    6. (2 articles) Soochow University
    7. (2 articles) Sebastian M. Waldstein
    8. (2 articles) Christian Simader
    9. (2 articles) Carl Zeiss Meditec
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    Imaging port wine stains by fiber optical coherence tomography Evaluation of long-term follow-up with neointimal coverage and stent apposition after sirolimus-eluting stent implantation by optical coherence tomography Cotton-Wool Spot and Optical Coherence Tomography of a Retinal Nerve Fiber Layer Defect Automated segmentation of the choroid from clinical SD-OCT Quantification of External Limiting Membrane Disruption Caused by Diabetic Macular Edema from SD-OCT Three-dimensional segmentation of fluid-associated abnormalities in retinal OCT: probability constrained graph-search-graph-cut. Quantifying disrupted outer retina-subretinal layer in SD-OCT images in choroidal neovascularization Three-dimensional automated choroidal volume assessment on standard spectral-domain optical coherence tomography and correlation with the level of diabetic macular edema Fast and memory-efficient LOGISMOS graph search for intraretinal layer segmentation of 3D macular OCT scans Validity of Automated Choroidal Segmentation in SS-OCT and SD-OCT The multi-spectral signal properties of multiple reference optical coherence tomography (Thesis) Calibration-free time-stretch optical coherence tomography with large imaging depth