School of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.
Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, USA.
Transl Vis Sci Technol. 2020 Oct 7;9(11):7. doi: 10.1167/tvst.9.11.7. eCollection 2020 Oct.
The purpose of this study was to investigate the effect of device and scan size on quantitative optical coherence tomography angiography (OCT-A) metrics.
The 3 × 3 mm scans from Optovue AngioVue and Zeiss AngioPlex systems were included for 18 eyes of 18 subjects without ocular pathology. The foveal avascular zone (FAZ) was segmented manually by two observers, from which estimates of FAZ area (using both the nominal image scale and the axial length corrected image scale) and acircularity were derived. Three scan sizes (3 mm, 6 mm HD, and 8 mm) from the AngioVue system were included for 15 eyes of 15 subjects without ocular pathology. For each subject, larger image sizes were resized to the same resolution as 3 × 3 mm scans, aligned, then cropped to a common area. FAZ area, FAZ acircularity, average and total parafoveal intercapillary area, vessel density, and vessel end points were computed.
Between the devices used here, there were no significant differences in FAZ acircularity ( = 0.88) or FAZ area using scaled ( = 0.11) or unscaled images ( = 0.069). Although there was no significant difference in FAZ area across scan sizes ( = 0.30), vessel morphometry metrics were all significantly influenced by scan size.
The scan devices and sizes used here do not affect FAZ area measures derived from manual segmentations. In contrast, vessel morphometry metrics are affected by scan size. As individual differences in axial length induce differences in absolute scan size, extreme care should be taken when interpreting metrics of vessel morphometry, both between and within OCT-A devices.
A better characterization of the confounds surrounding OCT-A retinal vasculature metrics can lead to improved application of these metrics as biomarkers for retinal and systemic diseases.
本研究旨在探讨设备和扫描尺寸对定量光相干断层扫描血管造影（OCT-A）指标的影响。
纳入 18 名受试者的 18 只眼，无眼部病变，获取 Optovue AngioVue 和 Zeiss AngioPlex 系统的 3×3mm 扫描。由两名观察者手动分割黄斑中心无血管区（FAZ），从 FAZ 面积（使用标称图像比例和轴向长度校正的图像比例）和非圆度的估计值。纳入 15 名无眼部病变受试者的 15 只眼，获取 AngioVue 系统的三种扫描尺寸（3mm、6mmHD 和 8mm）。对于每个受试者，较大的图像尺寸均按与 3×3mm 扫描相同的分辨率进行调整，然后对齐并裁剪到公共区域。计算 FAZ 面积、FAZ 非圆度、平均和总旁中心毛细血管区、血管密度和血管终点。
在此使用的设备之间，FAZ 非圆度（ = 0.88）或使用缩放（ = 0.11）或未缩放图像（ = 0.069）的 FAZ 面积无显著差异。尽管扫描尺寸之间 FAZ 面积无显著差异（ = 0.30），但血管形态计量学指标均受扫描尺寸影响。
在此使用的扫描设备和尺寸不会影响手动分割得出的 FAZ 面积测量值。相反，血管形态计量学指标受扫描尺寸影响。由于眼轴长度的个体差异导致绝对扫描尺寸的差异，因此在解释 OCT-A 血管形态计量学的指标时，无论是在 OCT-A 设备之间还是内部，都应格外小心。
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