Longitudinal study of multiple sclerosis lesions using ultra-high field (7T) multiparametric MR imaging.

Sanjeev Chawla,Friedemann Paul,Jens Wuerfel,Jean-Christophe Brisset,Tim Sinnecker,Ilya Kister,Yulin Ge,Quan Jiang

doi:10.1371/journal.pone.0202918

Abstract

Pathophysiology of multiple sclerosis (MS) lesions is dynamic and changes over time. The purpose of this exploratory study was to determine the longitudinal changes in MS lesions over time on ultra-high field MR imaging. Nine patients with MS underwent high-resolution 3D-susceptibility weighted imaging (SWI) and 2D-gradient-echo-T2*-weighted imaging on 7T MRI at baseline and after ~2.4 years of follow-up. Morphologic imaging characteristics, signal intensity patterns and quantitative susceptibility mapping (QSM) values of lesions were recorded at both time points. Lesions were classified as "iron-laden" if they demonstrated hypointense signal on T2*-weighted images and/or SWI as well as hyperintense signal on QSM. Lesions were considered "non-iron-laden" if they were hyperintense on T2*/SWI and isointense or hyperintense on QSM. Total of 162 non-iron-laden and 29 iron-laden lesions were observed at baseline. No change in baseline lesion size during follow up was recorded in 92.7%; no change in lesion-vessel relationship in 86.5%; and no change in signal intensity pattern in 96.9% of lesions. Three lesions which were non-iron-laden at baseline, exhibited iron at follow-up. In two iron-laden lesions, redistribution of iron content was observed at follow-up. Two-thirds of these iron-laden lesions showed an increase in QSM at follow-up relative to baseline, and the remaining one-third exhibited decrease in QSM. Most of the newly formed lesions (11/13, 84.6%) at follow-up were iron-laden. 7T multiparametric MRI is a useful tool for tracking the evolution of MS lesions, especially with regard to changes in iron content.

Highlights

Multiple sclerosis (MS), a chronic autoimmune disease, causes lesions in the central nervous system that are characterized by variable degree of inflammation, demyelination, axonal injury, and iron accumulation [1]
In a recent crosssectional study, four distinct patterns of MS lesions were described based on signal intensity pattern on ultrahigh field (7T) gradient echo-T2Ã (GRE-T2Ã), susceptibility weighted imaging (SWI) and quantitative susceptibility mapping (QSM) [2]
This study demonstrated that all lesions could be defined by MRI changes consistent with demyelination and inflammation, but that only a small number of lesions had evidence of iron accumulation either in nodular or ring-like pattern

Summary

Introduction

Multiple sclerosis (MS), a chronic autoimmune disease, causes lesions in the central nervous system that are characterized by variable degree of inflammation, demyelination, axonal injury, and iron accumulation [1]. MR imaging is routinely used to support the clinical diagnosis of MS, characterize disease activity, and monitor response to therapy. This study demonstrated that all lesions could be defined by MRI changes consistent with demyelination and inflammation, but that only a small number of lesions had evidence of iron accumulation either in nodular or ring-like pattern. These findings are consistent with previous histochemical studies [3, 4] that have shown that iron deposits were present only in a small subset of MS lesions. Advancing our understanding of the longitudinal pathophysiological changes of MS lesions may provide new opportunities to monitor disease progression and to suggest novel therapeutic interventions

Methods

Results

Conclusion