Schmidt Taly Gilat, Linderman Rachel E, Strampe Margaret R, Chui Toco Y P, Rosen Richard B, Carroll Joseph
Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, WI, USA.
Department of Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.
Transl Vis Sci Technol. 2019 Jan 18;8(1):10. doi: 10.1167/tvst.8.1.10. eCollection 2019 Jan.
This study proposes an optical coherence tomography angiography (OCTA) frame-averaging method and investigates the effects of the number of frames acquired and averaged on metrics quantifying the foveal avascular zone (FAZ), vessel morphology, and parafoveal intercapillary area (PICA).
Ten OCTA frames were acquired for each of the 19 subjects without known retinal disease using the AngioVue OCTA system. For each subject, acquired frames were ranked by an image quality metric. A subset of frames was then registered and averaged. The effects of the number of frames acquired and averaged on FAZ segmentation and metrics of FAZ geometry, vessel morphology, and PICA were analyzed.
Frame averaging increased the accuracy of the automatically segmented FAZ region; for example, the absolute error in FAZ area decreased from 0.026 mm (1 frame) to 0.005 mm (5 frames). Averaging multiple frames exponentially decreased the estimated number of vessel endpoints and increased the average vessel length with a 32% decrease in number of endpoints and 14% increase in average vessel length when averaging five frames compared with one. Frame averaging also improved the precision of PICA estimates.
Averaging multiple OCTA frames using the Optovue AngioVue system reduced error in FAZ segmentation and improved the robustness of OCTA vessel morphology and perfusion metrics. The study demonstrated limited benefit in acquiring and averaging more than five frames.
Averaging multiple OCTA frames improved the robustness of OCTA foveal biomarkers with limited benefit when averaging more than five frames.
本研究提出一种光学相干断层扫描血管造影（OCTA）帧平均方法，并研究采集和平均的帧数对量化黄斑无血管区（FAZ）、血管形态和黄斑旁毛细血管面积（PICA）的指标的影响。
使用AngioVue OCTA系统，为19名无已知视网膜疾病的受试者每人采集10帧OCTA图像。对于每名受试者，采集的图像根据图像质量指标进行排序。然后对一部分图像进行配准和平均。分析采集和平均的帧数对FAZ分割以及FAZ几何形状、血管形态和PICA指标的影响。
帧平均提高了自动分割的FAZ区域的准确性；例如，FAZ面积的绝对误差从0.026平方毫米（1帧）降至0.005平方毫米（5帧）。平均多帧可指数级减少估计的血管端点数量，并增加平均血管长度，与1帧相比，平均5帧时端点数量减少32%，平均血管长度增加14%。帧平均还提高了PICA估计的精度。
使用Optovue AngioVue系统平均多帧OCTA图像可减少FAZ分割中的误差，并提高OCTA血管形态和灌注指标的稳健性。该研究表明，采集和平均超过5帧的益处有限。
平均多帧OCTA图像提高了OCTA黄斑生物标志物的稳健性，平均超过5帧时益处有限。
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