New England Eye Center, Tufts Medical Center, Boston, MA, USA.
University of Hawai'i John A. Burns School of Medicine, Honolulu, HI, USA.
Graefes Arch Clin Exp Ophthalmol. 2020 May;258(5):979-986. doi: 10.1007/s00417-020-04610-1. Epub 2020 Feb 4.
To examine the effects of enhanced depth imaging (EDI) and en face averaging on global vascular measurements of optical coherence tomography angiography (OCTA) images.
All eyes were imaged with 3 mm × 3 mm fields centered at the fovea using the Carl Zeiss Cirrus 5000 spectral-domain OCTA, with and without EDI, and the Zeiss PLEX Elite 9000 swept-source OCTA. Vessel area density (VAD), vessel length (VL), and vessel diameter index (VDI) were calculated for the superficial capillary plexus (SCP) en face angiograms. For the choriocapillaris (CC), VAD and the number, total area, and average size of flow voids were calculated. These metrics were compared between SD- and SS-OCTA images, with and without en face averaging and EDI.
Both averaging and EDI had a significant effect on quantitative metrics. EDI images trended toward a decrease in SCP VAD. In the CC, EDI decreased average flow void size. Averaging increased CC VAD while decreasing number of flow voids, total flow void area, and average flow void size. With both averaging and EDI, SD-OCTA was not able to visualize as many CC flow voids, particularly of a smaller size, compared with SS-OCTA.
Averaging and EDI affect quantitative metrics from SCP and CC OCTA images. EDI resulted in a trend toward decreased VAD in SCP images. Averaging had a major effect on CC imaging. Even with the combination of EDI and en face averaging, SD-OCTA images do not appear to approximate SS-OCTA images in terms of quantitative metrics. This has implications for clinical and research use of SD-OCTA for retinal imaging.
研究增强深度成像（EDI）和共面平均对光学相干断层扫描血管造影（OCTA）图像全局血管测量的影响。
使用 Carl Zeiss Cirrus 5000 光谱域 OCTA 和 Zeiss PLEX Elite 9000 扫频源 OCTA，对黄斑中心凹 3mm×3mm 区域进行成像，分别记录有无 EDI 的情况下的浅层毛细血管丛（SCP）共面血管造影图的血管面积密度（VAD）、血管长度（VL）和血管直径指数（VDI）。对脉络膜毛细血管（CC），计算 VAD 和血流空洞的数量、总面积和平均大小。将这些指标与 SD-OCTA 和 SS-OCTA 图像进行比较，比较有无共面平均和 EDI 的情况。
平均和 EDI 对定量指标均有显著影响。EDI 图像中 SCP 的 VAD 呈下降趋势。在 CC 中，EDI 降低了平均血流空洞大小。平均化增加了 CC 的 VAD，同时减少了血流空洞的数量、总面积和平均血流空洞大小。与 SS-OCTA 相比，SD-OCTA 无论是在有无平均和 EDI 的情况下，都无法显示出那么多的 CC 血流空洞，特别是较小尺寸的血流空洞。
平均和 EDI 影响 SCP 和 CC 的 OCTA 图像的定量指标。EDI 导致 SCP 图像的 VAD 呈下降趋势。平均化对 CC 成像有重大影响。即使结合 EDI 和共面平均，SD-OCTA 图像在定量指标上似乎也无法接近 SS-OCTA 图像。这对视网膜成像的 SD-OCTA 的临床和研究应用有影响。
