Department of Bioengineering, University of Washington, Seattle, Washington.
Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA.
Am J Ophthalmol. 2019 Dec;208:111-123. doi: 10.1016/j.ajo.2019.07.003. Epub 2019 Jul 16.
To demonstrate the variation in quantitative choriocapillaris (CC) metrics with various binarization approaches using optical coherence tomography angiography (OCTA).
Retrospective, observational, cross-sectional case series.
Macular OCTA scans, 3- × 3-mm and 6- × 6-mm, were obtained from normal eyes and from eyes with drusen secondary to age-related macular degeneration (AMD). The CC slab was extracted, and the CC flow deficits (FDs) were segmented with 2 previously published algorithms: the fuzzy C-means approach (FCM method) and Phansalkar's local thresholding (Phansalkar method). Four different values for the radius were used in order to investigate the effect on the FD segmentation when using the Phansalkar method. FD density (FDD), mean FD size (MFDS), FD number (FDN), FD area (FDA) and intercapillary distance (ICD) were calculated for comparison. Repeatability was assessed as coefficient of variation (CV), and Pearson's correlation analysis was conducted.
Six eyes from 6 subjects with normal eyes and 6 eyes from 6 subjects with drusen secondary to AMD were scanned. The 3- × 3-mm scans resulted in higher repeatability than the 6- × 6-mm scans. For the Phansalkar method, larger values of the radius resulted in higher repeatability. ANOVA tests resulted in significant differences (P < 0.001) among the FCM method and the Phansalkar method with different radius options for all CC metrics and scan sizes investigated. In 3- × 3-mm scans, significant correlation was found between the FCM method and the Phansalkar method for all quantitative CC metrics other than FDN (all P < 0.001; 0.90 < r <0.99).
Quantitative CC analysis with commercially available OCTA is complicated and researchers need to pay close attention to how they conduct such analyses.
利用光相干断层扫描血管造影术（OCTA）展示各种二值化方法对脉络膜毛细血管（CC）定量指标的变化。
回顾性、观察性、病例系列的横断面研究。
从正常眼和年龄相关性黄斑变性（AMD）继发的玻璃膜疣眼中获得黄斑 OCTA 扫描，大小为 3×3mm 和 6×6mm。提取 CC 板层，使用两种已发表的算法对 CC 血流不足（FD）进行分割：模糊 C-均值方法（FCM 方法）和 Phansalkar 的局部阈值法（Phansalkar 方法）。为了研究 Phansalkar 方法中使用不同半径对 FD 分割的影响，使用了 4 个不同的半径值。计算 FD 密度（FDD）、平均 FD 大小（MFDS）、FD 数量（FDN）、FD 面积（FDA）和毛细血管间距离（ICD）进行比较。用变异系数（CV）评估重复性，并进行 Pearson 相关分析。
对 6 名正常眼受试者的 6 只眼和 6 名 AMD 继发玻璃膜疣眼受试者的 6 只眼进行了扫描。3×3mm 扫描的重复性高于 6×6mm 扫描。对于 Phansalkar 方法，半径越大，重复性越高。方差分析结果表明，在所研究的所有 CC 指标和扫描大小中，FCM 方法和不同半径选项的 Phansalkar 方法之间存在显著差异（P<0.001）。在 3×3mm 扫描中，FCM 方法和 Phansalkar 方法除了 FDN 之外，所有定量 CC 指标之间均存在显著相关性（均 P<0.001；0.90<r<0.99）。
利用商用 OCTA 进行定量 CC 分析较为复杂，研究人员需要密切关注其分析方法。
