Abstract
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 in vivo 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.
Highlights
Standard OCT has been widely used for the imaging and diagnosis of the posterior eye for over 20 years [1, 2], due to its high resolution, speed, and sensitivity
By comparing the images made by intensity averaging and the maximum a-posteriori (MAP) images, it can be seen that the intensity averaged images show a higher noise-offset in the low intensity regions, and have lower contrast compared with the corresponding MAP images
polarization diversity (PD)-detection and image composition removed polarization artifacts that were apparent in OCT images of the peripapillary sclera
Summary
Standard OCT has been widely used for the imaging and diagnosis of the posterior eye for over 20 years [1, 2], due to its high resolution, speed, and sensitivity. There have been many functional extensions to OCT [3], such as Doppler OCT [4,5,6,7], optical coherence angiography [7,8,9,10], polarization sensitive OCT [11,12,13,14,15,16,17,18], and spectroscopic OCT [19,20,21,22]. In posterior eye imaging, the vitreous body appears with a weak random signal, where one expects a much lower signal because its purpose is to be transparent
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