Synthetic MRI in Progressive MS: Associations with Disability.

Abstract

Background and purpose: Synthetic MRI (SyMRI) 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 detecting focal lesions and volumetric analysis. This study aimed to find an SyMRI variable associated with an Expanded Disability Status Scale (EDSS) ≥ 6 in progressive patients.

Materials and methods: Twenty-four patients with progressive MS underwent SyMRI with a 2D axial QRAPMASTER pulse sequence. We analyzed volumetric parameters, global myelin fraction (MyCF), and quantitative values derived from maps of proton density, R1, R2, and myelin for the masks: normal-appearing white and gray matter, lesion, and corpus callosum. A t test compared SyMRI variables between groups, followed by univariate binary logistic regression for significant (P < .05) or trending results (P < .09).

Results: Patients were categorized into 2 groups (EDSS < 6 versus ≥ 6). Variables with significant differences between groups were: brain parenchymal fraction (P = .05), white matter fraction (P = .05), MyCF (P = .04), and corpus callosum volume (P = .04). In the binary logistic regression analysis, the best predictor of the EDSS category was MyCF, with a P value of .08, and an OR of 0.59.

Conclusions: Our results confirm differences in volumetric parameters by EDSS by using a single MRI acquisition. Additionally, higher MyCF values were associated with lower disability, highlighting SyMRI and myelin quantification as potential tools for clinical practice.