Alten F, Lauermann J L, Clemens C R, Heiduschka P, Eter N
Department of Ophthalmology, University of Muenster Medical Center, Domagkstrasse 15, 48149, Muenster, Germany.
Graefes Arch Clin Exp Ophthalmol. 2017 Dec;255(12):2347-2355. doi: 10.1007/s00417-017-3813-8. Epub 2017 Oct 5.
To analyze signal reduction in choriocapillaris (CC) and segmentation errors in spectral domain optical coherence tomography angiography (OCT-A) caused by soft drusen due to age-related macular degeneration (AMD).
Twenty-four eyes of 24 patients underwent multimodal retinal imaging including central 3 × 3mm OCT-A (AngioVue, Optovue). Three drusen per study eye were randomly chosen and evaluated regarding drusen height, diameter, and accuracy of OCT-A layer segmentation in lesion proximity. Structural en-face OCT CC images were graded qualitatively and quantitatively regarding signal loss underneath the individual drusen area. Those drusen that showed no distinct signal loss in structural en-face OCT CC images were further evaluated in OCT-A. CC decorrelation signal index was measured within a 30-μm OCT-A CC slab in the exact area of drusen affection. Data were compared to healthy age-matched control subjects. Accuracy of layer segmentation, OCT CC data, and OCT-A CC data were correlated to morphological drusen parameters.
Mean drusen height and diameter were 91.57 ± 19.5μm and 315.17 ± 116.7μm. OCT-A layer segmentation of the inner plexiform layer (IPL) was disturbed by more than 50 μm in proximity to 26 drusen (36.1%). In these patients, drusen height was significantly higher compared to those with accurate IPL segmentation (p = 0.0126). Sixty-six out of 72 drusen (91.7%) caused a distinct signal loss in the structural en-face OCT CC image. Drusen height and drusen diameter were significantly higher in this group compared to the six drusen with a sufficient signal (p = 0.0276, p = 0.0025). CC decorrelation signal index measured in the area of these six drusen without OCT signal loss (8.3%) was reduced compared to age-matched healthy controls (73.6 vs. 100.1; p = 0.001).
Signal attenuation in CC slabs and segmentation errors of the IPL depend on drusen morphology. Both are frequent artifacts in OCT-A imaging in patients with soft drusen and must be considered during image analysis.
分析年龄相关性黄斑变性（AMD）所致软性玻璃膜疣引起的脉络膜毛细血管（CC）信号降低及光谱域光学相干断层扫描血管造影（OCT-A）中的分割误差。
24例患者的24只眼接受了多模式视网膜成像，包括中央3×3mm的OCT-A（AngioVue，Optovue）。每只研究眼随机选取3个玻璃膜疣，评估其高度、直径以及病变附近OCT-A层分割的准确性。对结构正面OCT CC图像中各个玻璃膜疣区域下方的信号损失进行定性和定量分级。在结构正面OCT CC图像中未显示明显信号损失的玻璃膜疣在OCT-A中进一步评估。在玻璃膜疣累及的确切区域内，在30μm厚的OCT-A CC层中测量CC去相关信号指数。将数据与年龄匹配的健康对照受试者进行比较。层分割的准确性、OCT CC数据和OCT-A CC数据与玻璃膜疣形态学参数相关。
玻璃膜疣的平均高度和直径分别为91.57±19.5μm和315.17±116.7μm。靠近26个玻璃膜疣（36.1%）处，内丛状层（IPL）的OCT-A层分割受干扰超过50μm。在这些患者中，玻璃膜疣高度显著高于IPL分割准确的患者（p = 0.0126）。72个玻璃膜疣中有66个（91.7%）在结构正面OCT CC图像中导致明显的信号损失。与6个信号充足的玻璃膜疣相比，该组玻璃膜疣的高度和直径显著更高（p = 0.0276，p = 0.0025）。在这6个无OCT信号损失的玻璃膜疣区域测量的CC去相关信号指数（8.3%）与年龄匹配的健康对照相比降低（73.6对100.1；p = 0.001）。
CC层中的信号衰减和IPL的分割误差取决于玻璃膜疣形态。两者都是软性玻璃膜疣患者OCT-A成像中常见的伪像，在图像分析过程中必须予以考虑。
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