Automatic estimation of retinal nerve fiber bundle orientation in SD-OCT images using a structure-oriented smoothing filter

Babak Ghafaryasl, Robert Baart, Johannes F. De Boer, Koenraad A. Vermeer, Lucas J. Van Vliet

    Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

    2 Citations (Scopus)
    52 Downloads (Pure)

    Abstract

    Optical coherence tomography (OCT) yields high-resolution, three-dimensional images of the retina. A better understanding of retinal nerve fiber bundle (RNFB) trajectories in combination with visual field data may be used for future diagnosis and monitoring of glaucoma. However, manual tracing of these bundles is a tedious task. In this work, we present an automatic technique to estimate the orientation of RNFBs from volumetric OCT scans. Our method consists of several steps, starting from automatic segmentation of the RNFL. Then, a stack of en face images around the posterior nerve fiber layer interface was extracted. The image showing the best visibility of RNFB trajectories was selected for further processing. After denoising the selected en face image, a semblance structure-oriented filter was applied to probe the strength of local linear structure in a discrete set of orientations creating an orientation space. Gaussian filtering along the orientation axis in this space is used to find the dominant orientation. Next, a confidence map was created to supplement the estimated orientation. This confidence map was used as pixel weight in normalized convolution to regularize the semblance filter response after which a new orientation estimate can be obtained. Finally, after several iterations an orientation field corresponding to the strongest local orientation was obtained. The RNFB orientations of six macular scans from three subjects were estimated. For all scans, visual inspection shows a good agreement between the estimated orientation fields and the RNFB trajectories in the en face images. Additionally, a good correlation between the orientation fields of two scans of the same subject was observed. Our method was also applied to a larger field of view around the macula. Manual tracing of the RNFB trajectories shows a good agreement with the automatically obtained streamlines obtained by fiber tracking.

    Original languageEnglish
    Title of host publicationMedical Imaging 2017
    Subtitle of host publicationImage Processing
    EditorsMartin A. Styner, Elsa D. Angelini
    Place of PublicationBellingham, WA
    PublisherSPIE
    Pages1-7
    Number of pages7
    ISBN (Electronic)9781510607118
    DOIs
    Publication statusPublished - 2017
    EventMedical Imaging 2017: Image Processing - Orlando, United States
    Duration: 12 Feb 201714 Feb 2017

    Publication series

    NameProceedings of SPIE
    Volume10133
    ISSN (Electronic)0277-786X

    Conference

    ConferenceMedical Imaging 2017: Image Processing
    Country/TerritoryUnited States
    CityOrlando
    Period12/02/1714/02/17

    Keywords

    • Normalized convolution
    • OCT
    • Retinal nerve fiber bundle
    • Semblance
    • Steerable filter

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