Intra‐session repeatability of quantitative metrics using widefield optical coherence tomography angiography (OCTA) in elderly subjects

Abstract

Purpose To assess the repeatability of retinal vascular metrics using different postprocessing methods as obtained from the swept‐source optical coherence tomography angiography ( SS ‐ OCTA ). Methods Thirty‐two participants (63% males; mean [ SD ] age, 70 [7] years) underwent SS ‐ OCTA imaging ( PLEX ® Elite 9000, Carl Zeiss Meditec, Inc., Dublin, USA ). Each participant underwent 2 repeated scans of 2 scan protocols: a macular‐centred 3 × 3‐mm 2 and a widefield 12 × 12‐mm 2 for a total of 4 acquisitions. Images of superficial vascular plexuses ( SVP ) and deep vascular plexuses ( DVP ) were processed using different filters to generate the perfusion density ( PD ) and vessel density ( VD ). Vessel enhancement filters ranged from vessel targeted (Hessian and Gabor filters), classical denoising (Gaussian filter), to a scale‐selective adaption (modified Bayesian residual transform [ MBRT ]). Intra‐session repeatability of the different filters and their correlation with the original data set were calculated with the intraclass correlation coefficient ( ICC ) and Pearson's r . Results Of the 32 eyes, 17 and 15 were right and left eyes, respectively. For 3 × 3‐mm 2 scans, both MBRT and Gabor filters yielded very good repeatable PD and VD (both ICC s > 0.87) values. Gabor filter was the most correlated with the original data set for the OCTA metrics ( r = 0.95–0.97). For 12 × 12‐mm 2 scans, MBRT filter produced good‐to‐moderate ICC values for SVP ( ICC >0.89) and DVP ( ICC >0.73) metrics. Both the MBRT and Gabor filters were highly correlated with the original 12 × 12‐mm 2 scan data set ( r = 0.96–0.98). The ICC s for the agreement between 3 × 3‐mm 2 and cropped 12 × 12‐mm 2 were high only for the PD values at the SVP layer and were poor for the VD at SVP and DVP measurements ( ICC < 0.50). ...

Focal Structure–Function Relationships in Primary Open-Angle Glaucoma Using OCT and OCT-A Measurements

“…Moghimi and coworkers 8 reported fewer measurable steps from a healthy mean value to a modeled residual floor for OCT-A vascular measures, suggesting that the larger dynamic range of vascular measures was offset by increased measurement variability. Although OCT-A has been demonstrated to have good repeatability in both and normal and diseased eyes, 49 , 50 other studies have shown that OCT-A measurements can be affected by signal strength 51 and choice of vascular processing approach, 52 as well as physiological characteristics, 53 among other factors. Given these potential sources of variability, these factors should be considered in a progression study, where it may also be advantageous to include baseline parameters.…”

Are choriocapillaris flow void features robust to diurnal variations? A swept-source optical coherence tomography angiography (OCTA) study

“…Second, different hardware and scanning protocols can result in a difference in the OCTA metrics, such as scanning speed, lateral resolution, numbers of A-scan and B-scan. We have shown that using different filters can generate perfusion density, ranging from 29.8 to 45.1% in a 3 × 3 mm 2 macula scan 31 . Therefore, OCTA metrics are not comparable without considering these factors.…”

“…Thus far, there is no consensus on which filter and which parameters are optimal for extracting the OCTA metrics. We have shown previously high perfusion density reproducibility using frangi filter 31 , and the parameters were tuned so that the binarized perfusion map has highest similarity to anatomy.…”

Comparison of retinal vessel diameter measurements from swept-source OCT angiography and adaptive optics ophthalmoscope

“…OCTA imaging was performed with a prototype SS-OCT instrument (Plex Elite 9000, Carl Zeiss Meditec, USA), which employs a wavelength swept source and detects the interference signal by a photodetector. 4 The light source has a central wavelength at 1050 nm with a scanning rate of 100 000 A-scans per second. The axial and lateral resolutions in tissue are 6.3 µm and 20 µm, respectively.…”