Towards Super-Resolution CEST MRI for Visualization of Small Structures

TL;DR

This paper demonstrates that neural network-based super-resolution significantly improves the quality of CEST MRI images, potentially enabling earlier detection of rheumatic diseases by visualizing small joint structures.

Contribution

It introduces neural network approaches, specifically ResNet, for super-resolution of CEST MRI, outperforming traditional up-sampling methods in image quality metrics.

Findings

Neural networks outperform traditional methods in super-resolution of CEST MRI.

ResNet achieved a PSNR of 32.29dB, NRMSE of 0.14, SSIM of 0.85.

Improved image quality may facilitate earlier detection of rheumatic diseases.

Abstract

The onset of rheumatic diseases such as rheumatoid arthritis is typically subclinical, which results in challenging early detection of the disease. However, characteristic changes in the anatomy can be detected using imaging techniques such as MRI or CT. Modern imaging techniques such as chemical exchange saturation transfer (CEST) MRI drive the hope to improve early detection even further through the imaging of metabolites in the body. To image small structures in the joints of patients, typically one of the first regions where changes due to the disease occur, a high resolution for the CEST MR imaging is necessary. Currently, however, CEST MR suffers from an inherently low resolution due to the underlying physical constraints of the acquisition. In this work we compared established up-sampling techniques to neural network-based super-resolution approaches. We could show, that neural networks are able to learn the mapping from low-resolution to high-resolution unsaturated CEST images considerably better than present methods. On the test set a PSNR of 32.29dB (+10%), a NRMSE of 0.14 (+28%), and a SSIM of 0.85 (+15%) could be achieved using a ResNet neural network, improving the baseline considerably. This work paves the way for the prospective investigation of neural networks for super-resolution CEST MRI and, followingly, might lead to a earlier detection of the onset of rheumatic diseases.