Depth-resolved visualization and quantification of hyper-reflective foci on OCT scans using optical attenuation coefficients

Abstract

Purpose : Depth-resolved visualization and quantification of hyper-reflective foci in the entire 3D OCT scan corresponding to intraretinal pigment migration and pigmentation along the retinal pigment epithelium (RPE) were achieved using an OAC-based algorithm.

Methods : Subjects with intraretinal hyper-reflective foci and increased reflectivity along the RPE were imaged using a SS-OCT (PLEX® Elite 9000; ZEISS, Dublin, CA) 6×6 mm macular scan pattern. Inner limiting membrane (ILM), RPE, and Bruch’s membrane (BM) were segmented using the manufacturer’s software. OCT scans were converted to images contrasted by OACs in linear space (Fig. 1A, B). Hyper-reflective foci judged by OACs within a slab from the ILM to 10 µm above the RPE were labeled in green as intraretinal pigmentary deposits. The RPE was color-coded from yellow to red to demonstrate OAC values in which foci of increased reflectivity were highlighted in red. The total pigment burden was segmented from the en face sum projection of an OAC slab from the ILM to BM using an adaptive thresholding method. En face areas of hyper-reflective foci identified by the algorithm were compared with manual segmentations.

Results : A total of 49 eyes from 42 patients were recruited. Visualization of these hyper-reflective lesions was successfully accomplished, and intraretinal hyper-reflective foci were distinguished from increased reflectivity along the RPE (Fig. 1D, E). Hyper-reflective lesions from 24 eyes were manually segmented by identifying intraretinal lesions on B-scans and choroidal hypo-transmission defects on sub-RPE slabs extending 64 to 400 µm below BM. A significant correlation was found in area measurements of the total pigment burden between automated and manual segmentations (P<0.001, Fig. 1C).

Conclusions : An automated algorithm based on OACs was able to visualize, localize and quantify hyper-reflective foci in the retina and along the RPE, and the automated quantifications were successfully validated against manual segmentations.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Figure 1. Visualization, localization, and quantification of hyper-reflective foci in the retina and along the RPE. (A, B) B-scans of OCT and OAC with hyper-reflective foci (arrow). (C) Correlation of total pigment burden measured by automated algorithm and manual segmentations. (D, E) 3D visualizations of intraretinal pigment migration (green) and pigmentation (red) along the RPE (yellow).