Lu Yifan, Wang Jay C, Cui Ying, Zhu Ying, Zeng Rebecca, Lu Edward S, Katz Raviv, Husain Deeba, Vavvas Demetrios G, Kim Leo A, Miller Joan W, Miller John B
Harvard Retinal Imaging Lab, Massachusetts Eye and Ear, Boston, MA, USA.
Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
Graefes Arch Clin Exp Ophthalmol. 2021 Jun;259(6):1493-1501. doi: 10.1007/s00417-020-04945-9. Epub 2020 Sep 25.
Optical coherence tomography angiography (OCT-A) is a novel imaging modality for the diagnosis of chorioretinal diseases. A number of FDA-approved OCT-A devices are currently commercially available, each with unique algorithms and scanning protocols. Although several published studies have compared different combinations of OCT-A machines, there is a lack of agreement on the consistency of measurements across OCT-A devices. Therefore, we conducted a prospective quantitative comparison of four available OCT-A platforms.
Subjects were scanned on four devices: Optovue RTVue-XR, Heidelberg Spectralis OCT2 module, Zeiss Plex Elite 9000 Swept-Source OCT, and Topcon DRI-OCT Triton Swept-Source OCT. 3 mm × 3 mm images were utilized for analysis. Foveal avascular zone (FAZ) area was separately and independently measured by two investigators. Fractal dimension (FD), superficial capillary plexus (SCP), and deep capillary plexus (DCP) vessel densities (VD) were calculated from binarized images using the Fiji image processing software. SCP and DCP VD were further calculated after images were skeletonized. Repeated measures ANOVA, post hoc tests, and interclass correlation coefficient (ICC) were performed for statistical analysis.
Sixteen healthy eyes from sixteen patients were scanned on the four devices. Images of five eyes from the Triton device were excluded due to poor image quality; thus, the authors performed two sets comparisons, one with and one without the Triton machine. FAZ area showed no significant difference across devices with an ICC of > 95%. However, there were statistically significant differences for SCP and DCP VD both before and after skeletonization (p < 0.05). Fractal analysis revealed no significant difference of FD at the SCP; however, a statistically significant difference was found for FD at the DCP layer (p < 0.05).
The results showed that FAZ measurements were consistent across all four devices, while significant differences in VD and FD measurements existed. Therefore, we suggest that for both clinical follow-up and research studies, FAZ area is a useful parameter for OCT-A image analysis when measurements are made on different machines, while VD and FD show significant variability when measured across devices.
光学相干断层扫描血管造影（OCT-A）是一种用于诊断脉络膜视网膜疾病的新型成像方式。目前有多种经美国食品药品监督管理局（FDA）批准的OCT-A设备在市场上销售，每种设备都有独特的算法和扫描协议。尽管已有多项研究比较了不同OCT-A机器的不同组合，但对于不同OCT-A设备测量结果的一致性尚无定论。因此，我们对四种可用的OCT-A平台进行了前瞻性定量比较。
对受试者使用四种设备进行扫描：Optovue RTVue-XR、海德堡Spectralis OCT2模块、蔡司Plex Elite 9000扫频光学相干断层扫描（SS-OCT）以及拓普康DRI-OCT Triton扫频光学相干断层扫描。使用3mm×3mm的图像进行分析。由两名研究人员分别独立测量中心凹无血管区（FAZ）面积。使用Fiji图像处理软件从二值化图像中计算分形维数（FD）、浅表毛细血管丛（SCP）和深部毛细血管丛（DCP）的血管密度（VD）。在图像进行骨架化处理后进一步计算SCP和DCP的VD。进行重复测量方差分析、事后检验以及组内相关系数（ICC）分析以进行统计分析。
对16名患者的16只健康眼睛使用这四种设备进行扫描。由于图像质量差，排除了Triton设备的5只眼睛的图像；因此，作者进行了两组比较，一组包含Triton机器，另一组不包含。FAZ面积在各设备之间无显著差异，ICC>95%。然而，在骨架化处理前后，SCP和DCP的VD均存在统计学显著差异（p<0.05）。分形分析显示SCP处的FD无显著差异；然而，在DCP层发现FD存在统计学显著差异（p<0.05）。
结果表明，所有四种设备测量的FAZ一致，而VD和FD测量存在显著差异。因此，我们建议，对于临床随访和研究，当在不同机器上进行测量时FAZ面积是OCT-A图像分析的一个有用参数，而跨设备测量时VD和FD显示出显著的变异性。
