Abstract
Purpose :
Optical coherence tomography angiography (OCTA) is a novel noninvasive imaging modality for detailed retinal vasculature evaluation. The reproducibility of vasculature image acquisitions is valuable for the follow-up of retinal disorders. We performed a prospective, observational clinical study to investigate the quantitative and qualitative reproducibility of OCTA image acquisitions of superficial (SVP), deep (DVP) and choroidal (CP) vascular plexus.
Methods :
Six eyes from four healthy young patients (25-35 years-old) were imaged four times using OCTA (Spectralis, Heidelberg Engineering). All scans followed the same acquisition protocol (10x10, ART5 frames, 512 sections, 6μm) and were prospectively collected using the follow-up software from Heidelberg. The time elapsed between each scan was a few seconds. Standardized images from SVP, DVP and CP were extracted using projection artifact removal option. Quantitative analysis included vascular density (VD) and fractal dimensions (FD). VD was estimated by calculating the black to total pixels ratio in binary images (ImageJ). For FD images were skeletonized and fractal box-counting analyses were conducted using Fractalyse (ThéMA). Intraclass correlation coefficient (ICC) (SPSS 22) was used to evaluate reliability of ratios and FD. Qualitative analysis was performed by creating overlapped colored layers (one color per image acquisition).
Results :
The overall ICC for VD was 0.91 (CI95%0.80-0.96). VD ICC was 0.97 (CI95%0.91-0.99) for SVP, 0.79 (CI95%0.22-0.97) for DVP and 0.86 (CI95%0.49-0.98) for CP. Overall ICC for FD was 0.96 (CI95%0.90-0.99). FD ICC was 0.89 (CI95%0.64-0.98) for SVP and 0.81 (CI95%0.33-0.97) for DVP. Qualitative analysis showed overall overlapping of vascular structures between scans. However, there are small differences between the acquired scans that can be identified.
Conclusions :
OCTA is a reliable technique for the follow-up of retinal vessels diseases in SVP. However, reliability decreases for DVP and CP where few small vessels may not be correctly identified in all scans. Small changes in vasculature must be identified with caution as they may be the result of acquisition artifacts. VD and FD were not significantly different for vascular changes monitoring.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.