Department of Ophthalmology, IRCCS Ospedale San Raffaele, University Vita-Salute, via Olgettina 60, 20132, Milan, Italy.
CNIT Research Unit, Department of Electrical and Electronic Engineering (DIEE), University of Cagliari, Cagliari, Italy.
Sci Rep. 2021 Apr 27;11(1):9094. doi: 10.1038/s41598-021-88681-y.
Optical coherence tomography (OCT) angiography (OCTA) is a non-invasive tool for the in-vivo study of the intraretinal vascular network. It is based on the analysis of motion particles within the retina to reconstruct the paths followed by the erythrocytes, i.e. retinal capillaries. To date, qualitative and quantitative information are based on the morphological features disclosed by retinal capillaries. In the present study, we proposed new quantitative functional metrics, named Total Flow Intensity (TFI), Active Flow Intensity (AFI), and Volume-related Flow Intensity (VFI), based on the processing of the blood flow signal detected by OCTA. We studied these metrics in a cohort of healthy subjects, and we assessed their clinical utility by including a cohort of age-matched patients affected by Stargardt disease. Moreover, we compared TFI, AFI, and VFI to the widely used vessel density (VD) parameter. TFI, AFI, and VFI were able to describe in detail the different properties of the retinal vascular compartment. In particular, TFI was intended as the overall amount of volumetric retinal blood flow. AFI represented a selective measure of voxels disclosing blood flow signal. VFI was developed to put in relationship the volumetric blood flow information with the not vascularized retinal volume. In conclusion, TFI, AFI, and VFI were proposed as feasible functional OCTA biomarkers based on the analysis of retinal blood flow signal.
光学相干断层扫描血管造影术（OCTA）是一种用于活体研究视网膜内血管网络的非侵入性工具。它基于对视网膜内运动粒子的分析，以重建红细胞（即视网膜毛细血管）所遵循的路径。迄今为止，定性和定量信息都是基于视网膜毛细血管所揭示的形态特征。在本研究中，我们基于 OCTA 检测到的血流信号处理，提出了新的定量功能指标，分别命名为总流量强度（TFI）、活跃流量强度（AFI）和与体积相关的流量强度（VFI）。我们在一组健康受试者中研究了这些指标，并通过纳入一组年龄匹配的患有 Stargardt 病的患者来评估它们的临床实用性。此外，我们还将 TFI、AFI 和 VFI 与广泛使用的血管密度（VD）参数进行了比较。TFI、AFI 和 VFI 能够详细描述视网膜血管腔的不同特性。特别是，TFI 被认为是视网膜总体积血流的量。AFI 代表了对显示血流信号的体素的选择性测量。VFI 旨在将血流信息与非血管化的视网膜体积联系起来。总之，TFI、AFI 和 VFI 被提议作为基于视网膜血流信号分析的可行的功能 OCTA 生物标志物。
