Synthetic MRI in progressive MS: associations with disability

Abstract

Background and purpose: Synthetic MRI is a short-time acquisition sequence that generates different contrast-weighted images based on the measurement of tissue properties and provides quantitative volumetric, relaxation, and myelin maps. It has been used as an alternative to conventional MRI sequences in relapsing-remitting MS for the detection of focal lesions and volumetric analysis. This study aimed to find a Synthetic MRI variable that would predict EDSS ≥ 6 in progressive patients. 

Materials and methods: 24 patients with progressive MS underwent SyMRI using a 2D axial QRAPMASTER pulse sequence. We have analyzed the segmentation map for volumetric parameters, global myelin fraction (MyCF). And, quantitative values derived from maps of PD, R1, R2, and myelin for the following masks: normal-appearing white and grey matter, lesion, and corpus callosum. A t-test compared SyMRI variables between groups, followed by univariate binary logistic regression for significant (p< 0.05) or trending results (p < 0.09).

Results:  Patients were categorized into two groups (EDSS <6 vs ≥ 6). Variables with significant differences between groups were: BPF (p=0.05), WMF (p=0.05), MyCF (p=0.04), and corpus callosum volume (p=0.04). In the binary logistic regression analysis, the best predictor was MyCF, the p-value of 0.08 and an odd ratio of 0.59.

Conclusions: Our results corroborate the differences in volumetric parameters according to EDSS using a single MRI acquisition. Besides, our findings suggest that higher MyCF values were associated with lower odds of having an EDSS score ≥6.