Amirmoezzi Yalda, Ghofrani-Jahromi Mohsen, Parsaei Hossein, Afarid Mehrdad, Mohsenipoor Negar
Department of Medical Physics and Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Shiraz Neuroscience Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
J Biomed Phys Eng. 2024 Feb 1;14(1):31-42. doi: 10.31661/jbpe.v0i0.2106-1349. eCollection 2024 Feb.
Qualitative and quantitative assessment of retinal perfusion using optical coherence tomography angiography (OCTA) has shown to be effective in the treatment and management of various retinal and optic nerve diseases. However, manual analyses of OCTA images to calculate metrics related to Foveal Avascular Zone (FAZ) morphology, and retinal vascular density and morphology are costly, time-consuming, subject to human error, and are exposed to both inter and intra operator variability.
This study aimed to develop an open-source software framework for quantitative OCTA (QOCTA). Particularly, for analyzing OCTA images and measuring several indices describing microvascular morphology, vessel morphology, and FAZ morphology.
In this analytical study, we developed a toolbox or QOCTA using image processing algorithms provided in MATLAB. The software automatically determines FAZ and measures several parameters related to both size and shape of FAZ including area, perimeter, Feret's diameter circularity, axial ratio, roundness, and solidity. The microvascular structure is derived from the processed image to estimate the vessel density (VD). To assess the reliability of the software, three independent operators measured the mentioned parameters for the eyes of 21 subjects. The consistency of the values was assessed using the intraclass correlation coefficient (ICC) index.
Excellent consistency was observed between the measurements completed for the superficial layer, ICC >0.9. For the deep layer, good reliability in the measurements was achieved, ICC >0.7.
The developed software is reliable; hence, it can facilitate quantitative OCTA, further statistical comparison in cohort OCTA studies, and can assist with obtaining deeper insights into retinal variations in various populations.
使用光学相干断层扫描血管造影（OCTA）对视网膜灌注进行定性和定量评估已被证明在各种视网膜和视神经疾病的治疗与管理中是有效的。然而，通过手动分析OCTA图像来计算与黄斑无血管区（FAZ）形态、视网膜血管密度和形态相关的指标，成本高、耗时、易出现人为误差，并且存在操作者间和操作者内的变异性。
本研究旨在开发一个用于定量OCTA（QOCTA）的开源软件框架。特别是用于分析OCTA图像并测量描述微血管形态、血管形态和FAZ形态的几个指标。
在这项分析研究中，我们使用MATLAB中提供的图像处理算法开发了一个QOCTA工具箱。该软件自动确定FAZ并测量与FAZ的大小和形状相关的几个参数，包括面积、周长、费雷特直径、圆形度、轴比、圆度和紧实度。从处理后的图像中得出微血管结构以估计血管密度（VD）。为了评估该软件的可靠性，三名独立的操作者对21名受试者的眼睛测量了上述参数。使用组内相关系数（ICC）指数评估值的一致性。
在浅层测量之间观察到极好的一致性，ICC>0.9。对于深层，测量具有良好的可靠性，ICC>0.7。
所开发的软件是可靠的；因此，它可以促进定量OCTA、队列OCTA研究中的进一步统计比较，并有助于更深入地了解不同人群的视网膜变化。
