Conversion Between CT and MRI Images Using Diffusion and Score-Matching Models
This addresses the need for cost-effective and aligned multi-modality imaging in medical diagnosis and treatment, such as radiotherapy planning, but is incremental as it applies existing deep learning frameworks to a known bottleneck.
The paper tackled the problem of converting MRI to CT images to reduce costs and misalignment in medical imaging by using diffusion and score-matching models, showing they generate better synthetic CT images than CNN and GAN models with improved results from uncertainty averaging.
MRI and CT are most widely used medical imaging modalities. It is often necessary to acquire multi-modality images for diagnosis and treatment such as radiotherapy planning. However, multi-modality imaging is not only costly but also introduces misalignment between MRI and CT images. To address this challenge, computational conversion is a viable approach between MRI and CT images, especially from MRI to CT images. In this paper, we propose to use an emerging deep learning framework called diffusion and score-matching models in this context. Specifically, we adapt denoising diffusion probabilistic and score-matching models, use four different sampling strategies, and compare their performance metrics with that using a convolutional neural network and a generative adversarial network model. Our results show that the diffusion and score-matching models generate better synthetic CT images than the CNN and GAN models. Furthermore, we investigate the uncertainties associated with the diffusion and score-matching networks using the Monte-Carlo method, and improve the results by averaging their Monte-Carlo outputs. Our study suggests that diffusion and score-matching models are powerful to generate high quality images conditioned on an image obtained using a complementary imaging modality, analytically rigorous with clear explainability, and highly competitive with CNNs and GANs for image synthesis.