1. Articles from Homayoun Bagherinia

    1-13 of 13
    1. A machine learning method for optical coherence tomography scan quality assessment

      A machine learning method for optical coherence tomography scan quality assessment

      Purpose : The reliability of automated analysis of optical coherence tomography (OCT) scans depends on the scan quality. Quality indicators in commercial instruments only provide an overall score and do not provide localized information. Here we demonstrated a quality map using a semi-supervised machine learning technique which can aid with identifying local areas of poor quality. Methods : Our method first computes a set of feature maps using signal strength, signal-to-noise ratio (SNR), and contrast for individual or a group of neighboring A-scans of 580 6x6x2mm OCT volumes with good and poor quality (Fig 1A shows one volume). It then combines the ...

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    2. Correction of decorrelation tail artifacts in a whole OCT-A volume

      Correction of decorrelation tail artifacts in a whole OCT-A volume

      A method and system for correction of decorrelation tail artifacts in optical coherence tomography (OCT) angiography volumetric data defines a movable target subvolume within the OCT-A volumetric data. The target subvolume is axially moveable within the OCT-A volumetric data in discrete axial steps. At each axial step, a reference subvolume corresponding to a depth location in the OCT A volumetric data is defined axially offset from the target subvolume. The reference subvolume may be defined within the OCT A volumetric data, or defined within a different (previously corrected) OCT-A volume. Irrespective, corrected OCT-A data that corrects for decorrelation tail artifacts ...

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    3. Systems and methods for reducing artifacts in OCT angiography images

      Systems and methods for reducing artifacts in OCT angiography images

      Various methods for reducing artifacts in OCT images of an eye are described. In one exemplary method, three dimensional OCT image data of the eye is collected. Motion contrast information is calculated in the OCT image data. A first image and a second image are created from the motion contrast information. The first and the second images depict vasculature information regarding one or more upper portions and one or more deeper portions, respectively. The second image contains artifacts. Using an inverse calculation, a third image is determined that can be mixed with the first image to generate the second image ...

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    4. Evaluation of Corneal Epithelial Thickness Imaged by the High Definition Optical Coherence Tomography in Healthy Eyes

      Evaluation of Corneal Epithelial Thickness Imaged by the High Definition Optical Coherence Tomography in Healthy Eyes

      Purpose: To evaluate corneal epithelial thickness (CET) and corneal thickness (CT) in healthy eyes using spectral domain optical coherence tomography. Methods: Thirty-six healthy eyes were imaged using the Cirrus high-definition (HD)-optical coherence tomography device. The average CET and CT were assessed using Cirrus Review Software within predefined concentric corneal ring-shaped zones. Specific regions of CET (superior, inferior, temporal, nasal, superonasal, inferotemporal, superotemporal, and inferonasal) were also assessed. The difference between zones was compared between males and females. Results: The average CET was 48.3, 47.1, 46.1, and 45.8 μm in the 4 concentric zones (0–2 ...

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    5. Evaluation of optical coherence tomographic data prior to segmentation

      Evaluation of optical coherence tomographic data prior to segmentation

      An efficient method of evaluating the level of contrast of an OCT dataset is presented. The method develops a metric to segregate useful and not-so-useful data in one or more OCT B-scans, in order to reduce spurious subsequent analyses of the data by downstream segmentation algorithms. It is designed to be fast and efficient and is applied to determining autofocus of an OCT instrument real-time and in identifying a real image from its complex conjugate twin.

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    6. Segmentation and enhanced visualization techniques for full-range fourier domain optical coherence tomography

      Segmentation and enhanced visualization techniques for full-range fourier domain optical coherence tomography

      Presented here are new processing techniques for optical coherence tomography (OCT) data that allow for improved visualization and use of full-range OCT images. These techniques minimize the central line artifact and the complex conjugate artifact without requiring additional system hardware or significantly increasing post-processing time. The central line artifact is minimized by normalizing each A-scan to account for ripples at the zero-delay position. The complex conjugate artifact is minimized by segmentation of a layer or layers that cross the zero-delay position, and in some embodiments by further segmentation of other surfaces based on the segmentation of the initial layer or ...

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    7. Systems & Methods For Ocular Anterior Segment Tracking, Alignment, And Dewarping Using Optical Coherence Tomography

      Systems & Methods For Ocular Anterior Segment Tracking, Alignment, And Dewarping Using Optical Coherence Tomography

      The present application discloses methods and systems to track the anterior segment while establishing a position of the delay which will permit good control of the placement of anterior segment structures. This allows accurate dewarping by maximizing the amount of corneal surface that is imaged as well as reducing or eliminating overlap between real and complex conjugate images present in frequency-domain optical coherence tomography. A method to dewarp surfaces given partial corneal surface information is also disclosed.

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    8. Systems And Methods For Variable Mode Optical Coherence Tomography Imaging

      Systems And Methods For Variable Mode Optical Coherence Tomography Imaging

      Systems and methods for improvements to optical coherence tomography systems for operating in different imaging modes are presented. In one embodiment, a system for identifying the presence and type of an adjunct lens operably connected to the OCT instrument for changing between imaging modes in the system is described. In a second embodiment, a system for dynamically autofocusing the OCT system depending on the layer of interest is presented.

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    9. Segmentation And Enhanced Visualization Techniques For FULL-RANGE Fourier Domain Optical Coherence Tomography

      Segmentation And Enhanced Visualization Techniques For FULL-RANGE Fourier Domain Optical Coherence Tomography

      Presented here are new processing techniques for optical coherence tomography (OCT) data that allow for improved visualization and use of full-range OCT images. These techniques minimize the central line artifact and the complex conjugate artifact without requiring additional system hardware or significantly increasing post-processing time. The central line artifact is minimized by normalizing each A-scan to account for ripples at the zero-delay position.

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    10. Systems And Methods For Enhanced Accuracy In OCT Imaging Of The Cornea

      Systems And Methods For Enhanced Accuracy In OCT Imaging Of The Cornea

      Systems and methods for enhanced accuracy in optical coherence tomography imaging of the cornea are presented, including approaches for more accurate corneal surface modeling, pachymetry maps, keratometric values, and corneal power. These methods involve new scan patterns, an eye tracking mechanism for transverse motion feedback, and advanced motion correction algorithms. In one embodiment the methods comprise acquiring a first sparse set of data, using that data to create a corneal surface model, and then using the model to register a second set of denser data acquisition. This second set of data is used to create a more accurate, motion-corrected model ...

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    11. Automated Detection of the Foveal Center Improves SD-OCT Measurements of Central Retinal Thickness

      Automated Detection of the Foveal Center Improves SD-OCT Measurements of Central Retinal Thickness

      BACKGROUND AND OBJECTIVE: To investigate the performance of an automated foveal center detection algorithm on spectral-domain optical coherence tomography (SD-OCT). PATIENTS AND METHODS: Fifty normal eyes and 50 eyes with early stage dry age-related macular degeneration (AMD) were analyzed. The actual scan center (SC), automatically detected foveal center (AF), and manually identified foveal center (MF) were compared. RESULTS: The mean of the radial distances was 89 ± 120 μm from MF to SC and 54 ± 41 μm from MF to AF for normal eyes and 179 ± 125 μm from SC to MF and 104 ± 62 μm from AF to MF for ...

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    12. Method for finding the lateral position of the fovea in an SDOCT image volume

      Method for finding the lateral position of the fovea in an SDOCT image volume
      Embodiments of the present invention provide methods for finding the lateral position of the fovea in an OCT image volume. In one instance, a cost function is developed whose minimum is located at or near the foveal center. This cost function includes one or more measures of retinal layer thickness and/or measures of distance from blood vessels or a priori locations.
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    1-13 of 13
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    Method for finding the lateral position of the fovea in an SDOCT image volume Automated Detection of the Foveal Center Improves SD-OCT Measurements of Central Retinal Thickness Systems And Methods For Enhanced Accuracy In OCT Imaging Of The Cornea Segmentation And Enhanced Visualization Techniques For FULL-RANGE Fourier Domain Optical Coherence Tomography Systems And Methods For Variable Mode Optical Coherence Tomography Imaging Systems & Methods For Ocular Anterior Segment Tracking, Alignment, And Dewarping Using Optical Coherence Tomography Segmentation and enhanced visualization techniques for full-range fourier domain optical coherence tomography Apparatus and methods for detecting optical components and their misalignment in optical coherence tomographic systems Evaluation of optical coherence tomographic data prior to segmentation Evaluation of Corneal Epithelial Thickness Imaged by the High Definition Optical Coherence Tomography in Healthy Eyes Optical coherence tomography angiography in glaucoma Handheld optical coherence tomography for clinical assessment of dental plaque and gingiva