Optical Coherence Tomography Angiography (OCTA) is a novel, non-invasive imaging modality of retinal capillaries at micron resolution. Recent studies have correlated macular OCTA vascular measures with retinal disease severity and supported their use as a diagnostic tool. However, these measurements mostly rely on a few summary statistics in retinal layers or regions of interest in the two-dimensional (2D) en face projection images. To enable 3D and localized comparisons of retinal vasculature between longitudinal scans and across populations, we develop a novel approach for mapping retinal vessel density from OCTA images. We first obtain a high-quality 3D representation of OCTA-based vessel networks via curvelet-based denoising and optimally oriented flux (OOF). Then, an effective 3D retinal vessel density mapping method is proposed. In this framework, a vessel density image (VDI) is constructed by diffusing the vessel mask derived from OOF-based analysis to the entire image volume. Subsequently, we utilize a non-linear, 3D OCT image registration method to provide localized comparisons of retinal vasculature across subjects. In our experimental results, we demonstrate an application of our method for longitudinal qualitative analysis of two pathological subjects with edema during the course of clinical care. Additionally, we quantitatively validate our method on synthetic data with simulated capillary dropout, a dataset obtained from a normal control (NC) population divided into two age groups and a dataset obtained from patients with diabetic retinopathy (DR). Our results show that we can successfully detect localized vascular changes caused by simulated capillary loss, normal aging, and DR pathology even in presence of edema. These results demonstrate the potential of the proposed framework in localized detection of microvascular changes and monitoring retinal disease progression.

中文翻译：

---

使用 OCT 血管造影进行 3D 视网膜血管密度测绘


光学相干断层扫描血管造影 (OCTA) 是一种新型、非侵入性的微米分辨率视网膜毛细血管成像方式。最近的研究将黄斑 OCTA 血管测量与视网膜疾病的严重程度相关联，并支持将其用作诊断工具。然而，这些测量主要依赖于二维 (2D) 视网膜层或感兴趣区域的一些汇总统计数据面对面投影图像。为了能够对纵向扫描之间和人群之间的视网膜血管系统进行 3D 和局部比较，我们开发了一种从 OCTA 图像中绘制视网膜血管密度的新方法。我们首先通过基于曲线的去噪和最优定向通量 (OOF) 获得基于 OCTA 的血管网络的高质量 3D 表示。然后，提出了一种有效的 3D 视网膜血管密度映射方法。在此框架中，通过将基于 OOF 的分析得出的血管掩模扩散到整个图像体积来构建血管密度图像 (​​VDI)。随后，我们利用非线性 3D OCT 图像配准方法来提供受试者视网膜脉管系统的局部比较。在我们的实验结果中，我们展示了我们的方法在临床护理过程中对两名水肿病理受试者进行纵向定性分析的应用。此外，我们使用模拟毛细血管脱落的合成数据定量验证我们的方法，该数据集是从分为两个年龄组的正常对照（NC）人群获得的数据集，以及从糖尿病视网膜病变（DR）患者获得的数据集。我们的结果表明，即使存在水肿，我们也可以成功检测由模拟毛细血管损失、正常衰老和 DR 病理引起的局部血管变化。 这些结果证明了所提出的框架在局部检测微血管变化和监测视网膜疾病进展方面的潜力。