1. Articles from Andreas Maier

    1-13 of 13

    1. Ultrahigh-Resolution Optical Coherence Tomography Investigation of Age-Related Changes in the Photoreceptors, Retinal Pigment Epithelium and Bruch’s Membrane

      Explore IOVS Journal Ophthalmology
      Ultrahigh-Resolution Optical Coherence Tomography Investigation of Age-Related Changes in the Photoreceptors, Retinal Pigment Epithelium and Bruch’s Membrane

      Purpose : Aging is the biggest risk factor for age-related macular degeneration (AMD). Previous histological and ultrastructural studies have suggested that photoreceptors (PR), retinal pigment epithelium (RPE), and Bruch’s membrane (BM) undergo changes with aging and in AMD. A new high-speed, ultrahigh-resolution optical coherence tomography (UHR OCT) prototype instrument with depth tracking and software motion correction was used to investigate PR/RPE/BM alterations in normal aging and early AMD. Methods : We developed a high-speed UHR OCT instrument with 2.7 µm axial resolution and 128 kHz A-scan rate. A galvanometer scanner actuates the OCT reference arm to match the ...

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      Mentions: Massachusetts Institute of Technology James G. Fujimoto Tufts University

    2. Correction propagation for user-assisted optical coherence tomography segmentation: general framework and application to Bruch’s membrane segmentation

      Explore OSA | OSA Publishing
      Correction propagation for user-assisted optical coherence tomography segmentation: general framework and application to Bruch’s membrane segmentation

      Optical coherence tomography (OCT) is a commonly used ophthalmic imaging modality. While OCT has traditionally been viewed cross-sectionally (i.e., as a sequence of B-scans), higher A-scan rates have increased interest in en face OCT visualization and analysis. The recent clinical introduction of OCT angiography (OCTA) has further spurred this interest, with chorioretinal OCTA being predominantly displayed via en face projections. Although en face visualization and quantitation are natural for many retinal features (e.g., drusen and vasculature), it requires segmentation. Because manual segmentation of volumetric OCT data is prohibitively laborious in many settings, there has been significant research and ...

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      Mentions: Massachusetts Institute of Technology James G. Fujimoto Tufts University

    3. Comparative study of deep learning models for optical coherence tomography angiography

      Explore OSA | OSA Publishing
      Comparative study of deep learning models for optical coherence tomography angiography

      Optical coherence tomography angiography (OCTA) is a promising imaging modality for microvasculature studies. Meanwhile, deep learning has achieved rapid development in image-to-image translation tasks. Some studies have proposed applying deep learning models to OCTA reconstruction and have obtained preliminary results. However, current studies are mostly limited to a few specific deep neural networks. In this paper, we conducted a comparative study to investigate OCTA reconstruction using deep learning models. Four representative network architectures including single-path models, U-shaped models, generative adversarial network (GAN)-based models and multi-path models were investigated on a dataset of OCTA images acquired from rat brains. Three ...

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      Mentions: University of Erlangen Gangjun Liu Peking University

    4. Compressed Sensing for Optical Coherence Tomography Angiography Volume Generation

      Explore Home - Springer Ophthalmology
      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto University of Erlangen

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

      Explore OSA | OSA Publishing
      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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      Mentions: University of Erlangen Gangjun Liu Peking University

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

      Explore LWW Online Ophthalmology
      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto David Huang

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

      Explore American Journal of Ophthalmology Ophthalmology
      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto Jay S. Duker

    8. Medical Imaging Systems An Introductory Guide

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      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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    9. Optical Coherence Tomography (Book Chapter)

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      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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      Mentions: James G. Fujimoto David Huang Eric A. Swanson

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

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      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto Tufts University

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

      Explore IOVS Journal Ophthalmology
      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto UC Davis

    12. Optical Coherence Tomography Angiography Characteristics of Iris Melanocytic Tumors

      Explore Elsevier Health Oncology , Ophthalmology
      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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      Mentions: Massachusetts Institute of Technology James G. Fujimoto David Huang

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

      Explore LWW Online Ophthalmology
      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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      Mentions: Philip J. Rosenfeld Massachusetts Institute of Technology James G. Fujimoto
    1-13 of 13
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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) 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 Comparative study of deep learning models for optical coherence tomography angiography Ultrahigh-Resolution Optical Coherence Tomography Investigation of Age-Related Changes in the Photoreceptors, Retinal Pigment Epithelium and Bruch’s Membrane Combining Deep Learning With Optical Coherence Tomography Imaging to Determine Scalp Hair and Follicle Counts Efficacy and Safety of Laser‐Assisted Combination Chemotherapy: An Explorative Imaging‐Guided Treatment With 5‐Fluorouracil and Cisplatin for Basal Cell Carcinoma