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. 2019 Jun 24;9:9096. doi: 10.1038/s41598-019-43958-1

Figure 4.

Figure 4

Illustration of cross-sectional, en face, and orthoplane approaches for artifact detection in an eye from a 68 year-old with mild NPDR; same eye as in Fig. 3. (A) 12 mm × 12 mm en face OCTA of retinal vasculature. (B) Corresponding en face OCT. (C–F) OCT B-scans extracted from the dashed blue lines labelled (c–f), respectively. In panels (A,B), the orange arrowheads point to the boundaries of segmentation artifacts (i.e., transitions from valid to invalid segmentation); note the abrupt change in the en face OCT at these locations (panel B). Yellow arrowheads point to the boundaries of thresholding artifacts; note the characteristic low signal in the en face OCT (panel B); red asterisks indicate regions of low OCTA signal caused by low-OCT-signal artifacts (either thresholding or segmentation artifacts), and green asterisks correspond to regions of low OCTA signal that correspond to true regions of low/no blood flow (i.e., areas of non-perfusion). In panels (C–F), orange arrows point to segmentation errors, and yellow arrows point to regions that generate thresholding artifacts as a result of low OCT signal. In the cross-sectional approach for artifact detection, only panels C–F are used; in the en face approach, only panels A and B are used; and, in the orthoplane approach, suspect regions are flagged using panels A and B, and cross-sectional OCT B-scans are taken through these locations (panels C–F).