1. Articles from Andreas Maier

    1-10 of 10
    1. Compressed Sensing for Optical Coherence Tomography Angiography Volume Generation

      Compressed Sensing for Optical Coherence Tomography Angiography Volume Generation

      Optical coherence tomography angiography (OCTA) is an increasingly popular modality for imaging of the retinal vasculature. Repeated optical coherence tomography (OCT) scans of the retina allow the computation of motion contrast to display the retinal vasculature. To the best of our knowledge, we present the first application of compressed sensing for the generation of OCTA volumes. Using a probabilistic signal model for the computation of OCTA volumes and a 3D median filter, it is possible to perform compressed sensing reconstruction of OCTA volumes while suppressing noise. The presented approach was tested on a ground truth, averaged from ten individual OCTA ...

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    2. Noise reduction in optical coherence tomography images using a deep neural network with perceptually-sensitive loss function

      Noise reduction in optical coherence tomography images using a deep neural network with perceptually-sensitive loss function

      Optical coherence tomography (OCT) is susceptible to the coherent noise, which is the speckle noise that deteriorates contrast and the detail structural information of OCT images, thus imposing significant limitations on the diagnostic capability of OCT. In this paper, we propose a novel OCT image denoising method by using an end-to-end deep learning network with a perceptually-sensitive loss function. The method has been validated on OCT images acquired from healthy volunteers’ eyes. The label images for training and evaluating OCT denoising deep learning models are images generated by averaging 50 frames of respective registered B-scans acquired from a region with ...

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    3. Application of Corneal Optical Coherence Tomography Angiography for Assessment of Vessel Depth in Corneal Neovascularization

      Application of Corneal Optical Coherence Tomography Angiography for Assessment of Vessel Depth in Corneal Neovascularization

      Purpose: To map and measure the depths of corneal neovascularization (NV) using 3-dimensional optical coherence tomography angiography (OCTA) at 2 different wavelengths. Methods: Corneal NV of varying severity, distribution, and underlying etiology was examined. Average NV depth and vessel density were measured using 840-nm spectral-domain OCTA and 1050-nm swept-source OCTA. The OCTA results were compared with clinical slit-lamp estimation of NV depth. Results: Twelve eyes with corneal NV from 12 patients were imaged with OCTA. Clinically “superficial,” “midstromal,” and “deep” cases had an average vessel depth of 23%, 39%, and 66% on 1050-nm OCTA, respectively. Average vessel depth on OCTA ...

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    4. A Framework for Multiscale Quantitation of Relationships Between Choriocapillaris Flow Impairment and Geographic Atrophy Growth

      A Framework for Multiscale Quantitation of Relationships Between Choriocapillaris Flow Impairment and Geographic Atrophy Growth

      Purpose To develop a multiscale analysis framework for investigating the relationships between geographic atrophy (GA) growth rate and choriocapillaris (CC) blood flow impairment using optical coherence tomography (OCT) and OCT angiography (OCTA). Design Retrospective case series. Methods We developed an OCT/OCTA analysis framework that quantitatively measures GA growth rates at global and local scales, and CC impairment at global, zonal, and local scales. A geometric GA growth model was used to measure local GA growth rates. The utility of the framework was demonstrated on 7 eyes with GA imaged at two time points using a prototype 400 kHz, 1050 ...

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    5. Medical Imaging Systems An Introductory Guide

      Medical Imaging Systems An Introductory Guide

      This open access book gives a complete and comprehensive introduction to the fields of medical imaging systems, as designed for a broad range of applications. The authors of the book first explain the foundations of system theory and image processing, before highlighting several modalities in a dedicated chapter. The initial focus is on modalities that are closely related to traditional camera systems such as endoscopy and microscopy. This is followed by more complex image formation processes: magnetic resonance imaging, X-ray projection imaging, computed tomography, X-ray phase-contrast imaging, nuclear imaging, ultrasound, and optical coherence tomography.

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    6. Optical Coherence Tomography (Book Chapter)

      Optical Coherence Tomography (Book Chapter)

      OCT is an interferometry based three-dimensional imaging modality that can be used on scattering media, including several types of body tissues. It provides physicians with in-situ image data in micrometer resolution within seconds. OCT’s working principle is similar to ultrasound but uses light instead of sound waves and is also free of potentially harmful ionizing radiation while being non-invasive. OCT in ophthalmology (the branch of medicine concerned with the eyes) has been pioneered by David Huang, Eric Swanson, and James G. Fujimoto and has since become a standard modality and is widely used by clinicians on a daily basis ...

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    7. A Joint Probabilistic Model for Speckle Variance, Amplitude Decorrelation and Interframe Variance (IFV) Optical Coherence Tomography Angiography

      A Joint Probabilistic Model for Speckle Variance, Amplitude Decorrelation and Interframe Variance (IFV) Optical Coherence Tomography Angiography

      Optical Coherence Tomography Angiography (OCTA) is a general method to visualize blood flow in biological tissue. Despite its good results in practice, the commonly used Amplitude Decorrelation OCTA (AD-OCTA) measure suffers from a well-understood objective function, which makes it challenging to mathematically model post processing tasks like, e.g., denoising. In this paper, a probabilistic model is developed for the three OCTA measures Speckle Variance OCTA, ADOCTA and the newly proposed Interframe Variance OCTA (IFV-OCTA) to enable further tasks like regularization-based denoising. From a theoretical point of view, IFV-OCTA is shown to be in-between the other two methods and can ...

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    8. Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

      Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography

      Purpose : To examine outer retinal band changes after flash stimulus and subsequent dark adaptation with ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods : Five dark-adapted left eyes of five normal subjects were imaged with 3-μm axial-resolution UHR-OCT during 30 minutes of dark adaptation following 96%, 54%, 23%, and 0% full-field and 54% half-field rhodopsin bleach. We identified the ellipsoid zone inner segment/outer segment (EZ[IS/OS]), cone interdigitation zone (CIZ), rod interdigitation zone (RIZ), retinal pigment epithelium (RPE), and Bruch's membrane (BM) axial positions and generated two-dimensional thickness maps of the EZ(IS/OS) to the four bands. The ...

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    9. Optical Coherence Tomography Angiography Characteristics of Iris Melanocytic Tumors

      Optical Coherence Tomography Angiography Characteristics of Iris Melanocytic Tumors

      Purpose To evaluate tumor vasculature with optical coherence tomography angiography (OCTA) in malignant iris melanomas and benign iris lesions. Design Cross-sectional observational clinical study. Participants Patients with iris lesions and healthy volunteers. Methods Eyes were imaged using OCTA systems operating at 1050- and 840-nm wavelengths. Three-dimensional OCTA scans were acquired. Iris melanoma patients treated with radiation therapy were imaged again after I-125 plaque brachytherapy at 6 and 18 months. Main Outcome Measures OCT and OCTA images, qualitative evaluation of iris and tumor vasculature, and quantitative vessel density. Results One eye each of 8 normal volunteers and 9 patients with iris ...

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    10. TOWARD QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Visualizing Blood Flow Speeds in Ocular Pathology Using Variable Interscan Time Analysis

      TOWARD QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Visualizing Blood Flow Speeds in Ocular Pathology Using Variable Interscan Time Analysis

      Purpose: Currently available optical coherence tomography angiography systems provide information about blood flux but only limited information about blood flow speed. The authors develop a method for mapping the previously proposed variable interscan time analysis (VISTA) algorithm into a color display that encodes relative blood flow speed. Methods: Optical coherence tomography angiography was performed with a 1,050 nm, 400 kHz A-scan rate, swept source optical coherence tomography system using a 5 repeated B-scan protocol. Variable interscan time analysis was used to compute the optical coherence tomography angiography signal from B-scan pairs having 1.5 millisecond and 3.0 milliseconds ...

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    1-10 of 10
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  2. Topics in the News

    1. (8 articles) James G. Fujimoto
    2. (7 articles) Massachusetts Institute of Technology
    3. (4 articles) University of Erlangen
    4. (3 articles) Tufts University
    5. (3 articles) David Huang
    6. (3 articles) Nadia K. Waheed
    7. (3 articles) National Institutes of Health
    8. (2 articles) Center for Ophthalmic Optics and Lasers
    9. (2 articles) Oregon Health & Science University
    10. (2 articles) Yan Li
    11. (2 articles) Jay S. Duker
    12. (1 articles) University of Erlangen
    13. (1 articles) Peking University
    14. (1 articles) Universidade Federal de São Paulo
    15. (1 articles) Massachusetts Institute of Technology
    16. (1 articles) Joel Ramjist
    17. (1 articles) James G. Fujimoto
    18. (1 articles) Victor X. D. Yang
    19. (1 articles) Heidelberg Engineering
    20. (1 articles) Heidelberg Spectralis
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    TOWARD QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Visualizing Blood Flow Speeds in Ocular Pathology Using Variable Interscan Time Analysis Optical Coherence Tomography Angiography Characteristics of Iris Melanocytic Tumors Photoreceptor Layer Thickness Changes During Dark Adaptation Observed With Ultrahigh-Resolution Optical Coherence Tomography A Joint Probabilistic Model for Speckle Variance, Amplitude Decorrelation and Interframe Variance (IFV) Optical Coherence Tomography Angiography Optical Coherence Tomography (Book Chapter) Medical Imaging Systems An Introductory Guide A Framework for Multiscale Quantitation of Relationships Between Choriocapillaris Flow Impairment and Geographic Atrophy Growth Application of Corneal Optical Coherence Tomography Angiography for Assessment of Vessel Depth in Corneal Neovascularization Noise reduction in optical coherence tomography images using a deep neural network with perceptually-sensitive loss function Compressed Sensing for Optical Coherence Tomography Angiography Volume Generation Three-dimensional detection and quantification of defects in SiC by optical coherence tomography University of Illinois at Chicago Receives NIH Grant for Functional Tomography of Neurovascular Coupling Interactions in Healthy and Diseased Retinas