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Luis De Sisternes, Warren Lewis, Thomas Callan, Sophie Kubach, Sophie Bonnin, Ramin Tadayoni, Mary Durbin; OCTA volume combination for montaging and averaging. Invest. Ophthalmol. Vis. Sci. 2020;61(9):PB0086.
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Combining multiple optical coherence tomography angiography (OCTA) acquisitions is a powerful technique to produce structural and flow volumes with increased field of view (FOV) and sampling density from what is available with a singular acquisition. In this work we introduce a method to combine multiple OCTA volumes of varying FOV, sampling density and location in an efficient manner
We collected retinal volumes of varying FOV (ranging 2.25x2.25mm-15x15mm) and centering offsets using a PLEX® Elite 9000 with AngioPlex OCT Angiography (ZEISS, Dublin, CA). For each set of volumes from the same eye, a reference volume is automatically chosen as the one maximizing the area of overlap with the rest of the data. Volumetric registration functions are then obtained by registering each volume to the reference both topographically, using common keypoints in projected flow data, and axially, using retinal layer information in the structural data. The resulting registrations are mapped to an enlarged FOV encompassing the region covered by the set of volumes and sampling density equal to the highest available from the set, extrapolating registrations in non-overlapping regions considering distortion effects. Singular structural and flow volumes were then generated for the enlarged FOV by combining the registrations, producing higher-quality datasets. We evaluated the algorithm performance stitching volumetric data acquired at different locations as well as enhancing quality in overlapping locations where several scans are acquired.
We processed OCTA datasets in which higher-density volumes were acquired within a larger FOV reference and montage datasets in which volumes of 12x12mm or 15x15mm FOV were acquired with varying centering offset. Visual evaluation of the combined volumes demonstrated higher image quality and increased resolution compared to the reference in regions of overlap, both in the resulting structural B-scan and flow data slabs, as well as appropriate montaging of the volumetric data in non-overlapping regions (see figure 1).
The presented method can combine OCTA volumes of different FOV and positioning, producing a combined volume that takes advantage of the area covered by scans with larger FOV and the detail of higher-density scans as well as montaging capabilities.
This is a 2020 Imaging in the Eye Conference abstract.
Structural B-scan and superficial flow slab of a reference acquisition and combined volume in two different example scenarios.
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