Unsupervised Denoising of Retinal OCT with Diffusion Probabilistic Model
This work addresses the challenge of denoising retinal OCT images for medical imaging applications, offering an unsupervised approach that is incremental over existing deep learning methods.
The paper tackles the problem of speckle noise degrading retinal OCT image quality by proposing a fully unsupervised diffusion probabilistic model that learns from noise rather than requiring clean reference images, resulting in significant image quality improvement with a simple pipeline and minimal training data.
Optical coherence tomography (OCT) is a prevalent non-invasive imaging method which provides high resolution volumetric visualization of retina. However, its inherent defect, the speckle noise, can seriously deteriorate the tissue visibility in OCT. Deep learning based approaches have been widely used for image restoration, but most of these require a noise-free reference image for supervision. In this study, we present a diffusion probabilistic model that is fully unsupervised to learn from noise instead of signal. A diffusion process is defined by adding a sequence of Gaussian noise to self-fused OCT b-scans. Then the reverse process of diffusion, modeled by a Markov chain, provides an adjustable level of denoising. Our experiment results demonstrate that our method can significantly improve the image quality with a simple working pipeline and a small amount of training data.