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Min Gao, Tristan Hormel, Yukun Guo, Steven T. Bailey, Christina J Flaxel, David Huang, Thomas S Hwang, Yali Jia; Identification and characterization of microaneurysm in OCT and OCT angiography. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2899 – F0052.
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© ARVO (1962-2015); The Authors (2016-present)
To identify microaneurysms (MA) in optical coherence tomography (OCT) and OCT angiography (OCTA) and explore the relationship between MAs and retinal fluid.
We obtained four 3×3-mm OCT and OCTA scans with a 400×400 sampling density on one eye of each participant with diabetic retinopathy with a commercial 120-kHz spectral-domain OCT system (Solix; Optovue, Inc.). A projection-resolved algorithm suppressed projection artifacts. A subset of participants also underwent multimodal imaging with color fundus photography and fluorescein angiography, used to identify features of MAs in OCT B-scans and OCT/OCTA en face images. MAs were manually segmented in the OCT and OCTA en face images. We classified MAs as active vs. inactive based on the presence of flow signal within the MA. We compared the amount of fluid in the 0.4mm-diameter circular area including the whole thickness of the retina surrounding the active vs. inactive MAs. A deep learning-based method automatically quantified the fluid volume.
Based on features identified on five eyes that underwent multimodal imaging, [Fig .1], we identified 173 MAs in 35 eyes. MAs were very bright round or irregular spots on OCT en face images [Fig .2 (A)]. Located mainly between the inner nuclear layer and outer plexiform layer, MAs show a strongly reflective wall in OCT B-scans [Fig .2 (C)]. MAs in OCT en face images (2.94±3.20 mm2) appear larger than in OCTA (1.33±1.15 mm2, Mann-Whitney U test, P<0.001) [Fig .2 (D)]. Seventy-five of 173 had a strong flow signal in OCTA [Fig .2 (B)] and were classified as active. Active MAs had a significantly higher probability of having retinal fluid nearby compared to inactive MA (57/75, 76.00% vs. 59/98, 60.20%, Z test, P=0.013). The mean fluid volume near the active MAs (3.63±4.94 mm3) compared to the inactive MAs (1.09 ±2.46 mm3) was significantly larger (Mann-Whitney U test, P<0.001).
MAs have distinct features on OCT and OCTA images that correlate with observations on multimodal imaging. MAs with flow signals on OCTA are more likely to have associated retinal fluid than those without, suggesting OCTA may identify MAs associated with more leakage.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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