Chan Aaron C, Hong Young-Joo, Makita Shuichi, Miura Masahiro, Yasuno Yoshiaki
Computational Optics Group, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan.
Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
Biomed Opt Express. 2017 Mar 3;8(4):2069-2087. doi: 10.1364/BOE.8.002069. eCollection 2017 Apr 1.
We propose using maximum a-posteriori (MAP) estimation to improve the image signal-to-noise ratio (SNR) in polarization diversity (PD) optical coherence tomography. PD-detection removes polarization artifacts, which are common when imaging highly birefringent tissue or when using a flexible fiber catheter. However, dividing the probe power to two polarization detection channels inevitably reduces the SNR. Applying MAP estimation to PD-OCT allows for the removal of polarization artifacts while maintaining and improving image SNR. The effectiveness of the MAP-PD method is evaluated by comparing it with MAP-non-PD, intensity averaged PD, and intensity averaged non-PD methods. Evaluation was conducted with human eyes. The MAP-PD method is found to be optimal, demonstrating high SNR and artifact suppression, especially for highly birefringent tissue, such as the peripapillary sclera. The MAP-PD based attenuation coefficient image also shows better differentiation of attenuation levels than non-MAP attenuation images.
我们建议使用最大后验(MAP)估计来提高偏振分集(PD)光学相干断层扫描中的图像信噪比(SNR)。PD检测可消除偏振伪影,这种伪影在对高度双折射组织成像或使用柔性光纤导管时很常见。然而,将探测功率分配到两个偏振检测通道不可避免地会降低SNR。将MAP估计应用于PD-OCT可以在去除偏振伪影的同时保持并提高图像SNR。通过将MAP-PD方法与MAP-非PD、强度平均PD和强度平均非PD方法进行比较,评估了MAP-PD方法的有效性。使用人眼进行了评估。发现MAP-PD方法是最优的,显示出高SNR和伪影抑制能力,特别是对于高度双折射组织,如视乳头周围巩膜。基于MAP-PD的衰减系数图像也比非MAP衰减图像显示出更好的衰减水平差异。