AI-Driven MRI Analysis Reveals Brain Atrophy Patterns in Benign Relapsing-Remitting Multiple Sclerosis

Marja Niiranen^1*Paula Bendel²Juha Koikkalainen³Jyrki Lötjönen³Tuomas Selander⁴Eino Solje¹Päivi Hartikainen¹Sakari Simula⁵Ritva Vanninen²Anne Portaankorva⁶

• ¹Neurocenter, Kuopio University Hospital, Kuopio, Finland
• ²Deparment of Clinical Radiology, Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Northern Savonia, Finland
• ³Combinostics Oy, Tampere, Pirkanmaa, Finland
• ⁴Science Service Center, Kuopio University Hospital, Kuopio, Northern Savonia, Finland
• ⁵Department of Neurology, Mikkeli Central Hospital, Mikkeli, Southern Savonia, Finland
• ⁶Clinical Neurosciences, University of Helsinki, Helsinki, Finland

The existence and definition of benign multiple sclerosis (MS) remain controversial, particularly given the discrepancy between clinical presentation and underlying imaging changes.In this study, we aimed to investigate the brain atrophy patterns related to benign relapsing-remitting MS (BRRMS), particularly regarding location and extent. We analyzed global and regional grey matter (GM) and white matter (WM) volumes, WM lesion load, corpus callosum index (CCI) and corpus callosum area (CCA) in well-defined benign relapsing-remitting MS patients (BRRMS, n = 35) compared to healthy controls (HC, n = 35). Imaging data were analyzed using an AI-based volumetric analysis MRI (cNeuro®) and confirmed visually by an experienced neuroradiologist, ensuring robust validation.Results: Total brain tissue volume was significantly smaller in patients with BRRMS compared to HC (p < 0.001), but the cortical (p = 0.011) and cerebral (p = 0.002) GM volumes, as well as cingulate gyrus (p=0.032) and entorhinal area volumes (p < 0.001), were larger in BRRMS. GM volumes in the postcentral gyrus (p = 0.001), precentral gyrus (p < 0.001), the medial segment of the precentral gyrus (p < 0.001), supplementary motor cortex (p < 0.001) and thalamus (p < 0.001) were reduced in BRRMS compared to HC. Furthermore, both CCI and CCA were significantly smaller in BRRMS (p < 0.001 and p = 0.001, respectively).Conclusions: Despite the overall reduced brain volume compared to HC, distinct cortical regions, especially within the limbic system (i.e. cingulate gyrus and entorhinal area) GM may be relatively well preserved, indicating a possible compensatory volume increase. Based on this study, the corpus callosum is a crucial structure in monitoring disease progression in BRRMS.for Merck and Sanofi, paid to his institution. ES has served on the advisory board of Novartis, EISAI and Roche, served as a consultant for Novo Nordisk, and received honoraria for lectures from Lundbeck and Roche. Other authors have no conflicts of interest.