Repeatability and Reproducibility of Superficial Macular Retinal Vessel Density Measurements Using Optical Coherence Tomography Angiography En Face Images

Abstract

IMPORTANCEThe repeatability and reproducibility of quantitative metrics from optical coherence tomographic angiography (OCTA) must be assessed before these data can be confidently interpreted in clinical research and practice.OBJECTIVE To evaluate the repeatability and reproducibility of OCTA-derived retinal vascular quantitative metrics. DESIGN, SETTING AND PARTICIPANTSIn this cross-sectional study, 21 healthy volunteers (42 eyes) and 22 patients with retinal disease (22 eyes), including 14 with age-related macular degeneration, 3 with epiretinal membrane, 2 with diabetic retinopathy, 2 with myopic macular degeneration, and 1 with retinal vein occlusion, were enrolled. Participants were recruited from September 1 through November 31, 2016. Each eye underwent 3 repeated scans with 3 instruments for a total of 9 acquisitions. Eyes were randomly assigned to scanning with a 3 × 3-mm or 6 × 6-mm pattern. Eyes were excluded from subsequent analysis if any acquisition had a signal strength of less than 7. Repeatability (defined as the agreement in measurements within a device) and reproducibility (defined as the agreement between devices of the same type) were assessed by intraclass correlation coefficient (ICC) and coefficient of variation.EXPOSURES All eyes underwent scanning using 3 separate devices. MAIN OUTCOMES AND MEASURES Vessel length density (VLD) and perfusion density (PD) of the superficial retinal vasculature.RESULTS A total of 21 healthy volunteers (8 men and 13 women; mean [SD] age, 36 [6] years) and 22 patients with retinal disease (15 men and 7 women; mean [SD] age, 79 [9] years) underwent evaluation. Of these, 40 of 42 normal eyes and 15 of 22 eyes with retinal disease met signal strength criteria and were included in this analysis. The ICC among the 3 consecutive scans ranged from 0.82 to 0.98 for VLD and from 0.83 to 0.95 for PD. The coefficient of variation (CV) ranged from 2.2% to 5.9% for VLD and from 2.4% to 5.9% for PD. For reproducibility, the ICC ranged from 0.62 to 0.95 and the CV was less than 6% in all groups. The agreement was highest for the 3 × 3-mm pattern in the inner ring (ICC range, 0.92 [95% CI, 0.85-0.96] to 0.96 [95% CI, 0.93-0.98]) and 6 × 6-mm pattern in the outer ring (ICC range, 0.93 [95% CI, 0.86-0.97] to 0.96 [95% CI, 0.92-0.98]).CONCLUSIONS AND RELEVANCE Vessel length density and PD of the superficial retinal vasculature can be obtained from OCTA images with high levels of repeatability and reproducibility but can vary with scan pattern and location.

Repeatability of vessel density measurements using optical coherence tomography angiography in retinal diseases

“…14 Lei et al reported that the difference in signal strength between scans was positively correlated with the difference in VD and PD measurements and also reported that if the signal strength increased by one unit, the VD increased by 1.4 mm -1 when the signal strength was at least 7. 10 Similarly, we found a statistically significant correlation between signal strength and the mean VD (B, 1.16; p<0.001), and the signal strength and repeatability of the VD were also significantly correlated using univariate regression (table 3). Although they did not show a statistically significant result in multivariate regression, the signal strength and VD seem to have a tendency towards a positive correlation.…”

“…3 OCTA also provides quantitative metrics about the retinal microvasculature, so it can help identify subclinical retinal vascular diseases and can assist in the diagnoses and follow-ups of many types of retinal diseases. 4 5 The Cirrus HD-OCT 5000 with AngioPlex software (Carl Zeiss Meditec, Dublin, California, USA; V. 10.0) automatically provides quantitative measurements of the vessel density (VD), perfusion density (PD) and foveal avascular zone (FAZ) area of the superficial capillary plexus. These metrics can be useful in clinical practice for patients with many types of retinal diseases, but establishing the repeatability of these measurements is critical for its use in clinical situation.…”

“…Various studies have reported the repeatability of OCTA measurements in the normal eye, but studies seem insufficient regarding the repeatability in patients with retinal diseases. [6][7][8][9][10][11] Therefore, in the present study, we determined the repeatability of VD measurements using OCTA in patients with diabetic macular oedema (DME), retinal vein occlusion (RVO) with macular oedema, epiretinal membrane (ERM) and wet age-related macular degeneration (AMD), which are relatively common in clinical field, and identified factors affecting the repeatability of these measurement.…”

Wide-field en face swept-source optical coherence tomography angiography using extended field imaging in diabetic retinopathy

“…It should be noted that VD showed significantly lower values in EFI SS-OCTA than in SS-OCTA images acquired without EFI. This is not surprising as we have seen lower VD values in 6×6 mm field images compare to 3×3 mm field images in a prior study—this was thought to be due to differences in transverse resolution between difference scan patterns 17. One would expect EFI scans that cover a larger territory (with the same number of A-scans) would have an effective lower resolution, which would translate to a lower VD.…”

Quantifying vascular density and morphology using different swept-source optical coherence tomography angiographic scan patterns in diabetic retinopathy

“…Previously, we observed lower VDs in 6×6 mm vs 3×3 mm spectral-domain OCTA images, likely because 6×6 mm scans cover a larger territory with the same number of A-scans, and thus have a lower effective resolution and lower VDs, than do 3×3 mm scans 18. Similarly, since 6×6 mm and 12×12 mm SS-OCTA images have lower resolutions than do 3×3 mm SS-OCTA images, they may also have a lower resolution with which to identify microvasculature damage.…”