Evolution of Chronic Lesion Tissue in RRMS patients: An association with disease progression

Abstract

AbstractBackground and ObjectiveThis study examines the long-term changes in Chronic Lesion Tissue (CLT) among relapsing and remitting MS (RRMS) patients, focusing on its impact on clinical and radiological disease progression indicators.MethodsThe study involved 72 MS patients with at least a 5-year follow-up. Annual assessments used 3D FLAIR, pre- and post-contrast 3D T1, and diffusion-weighted MRI. Lesion segmentation was conducted using iQ-MSTMsoftware, while brain structures were segmented using AssemblyNet. Volumetric changes in CLT were tracked using a custom-designed pipeline.ResultsThroughout the follow-up period, the volume of CLT in the entire cohort increased continuously and steadily, averaging 7.75±8.2% or 315±465 mm³ per year. Patients with expanding CLT experienced significantly faster brain atrophy, affecting both white and grey matter, particularly in the brain’s central area. Expanded CLT was also associated with higher and worsening EDSS scores, in contrast to the stable CLT group, where EDSS remained unchanged.ConclusionThis study demonstrates that, over a period of up to 7 years, patient-specific enlargement of CLT, where present, progresses at a constant rate and significantly influences disease progression.