Structural and Functional Brain Alterations in Multiple Sclerosis Patients Using Magnetic Resonance Imaging رسالة ماجستير

Abstract

Multiple sclerosis (MS) is a neurodegenerative disease that identified by the demyelination process and axonal damage, which badly affects the brain function and connectivity. Resting-state functional magnetic resonance imaging (rs-fMRI) is an effective tool that profounds useful insights into alterations in brain activity and connectivity within MS patients. Core resting-state networks (RSNs)—such as the Default Mode Network (DMN), Central Executive Network (CEN), and Salience Network (SN)—play crucial roles in cognitive and motor processes. Examining disruptions within these networks in MS can enhance the understanding of the disease's underlying mechanisms and aid in identifying potential biomarkers for its progression. Purpose This study aims to explore alterations in brain activity and functional connectivity within resting-state networks in MS patients compared to healthy controls, by focusing on three key measures of (rs-fMRI): amplitude of low-frequency fluctuations (ALFF) to assess spontaneous neural activity, degree centrality (DC) to evaluate global connectivity, and regional homogeneity (ReHo) to examine local connectivity across the brain. Methods Resting-state fMRI and structural (T1-3D ISO) data were collected from 20 MS patients and 20 age-matched healthy controls (HCs) using a 1.5 T Philips scanner. The DPABI toolbox was used to compute brain activity and connectivity, degree centrality (global connectivity), and regional homogeneity (local connectivity) after applying the preprocessing pipeline, which included mainly slice timing correction, realignment, nuisance V covariates regression, and temporal filtering between 0.01 and 0.08 Hz. The activity and connectivity matrices were extracted from RSNs, including 18 brain regions. Result The results showed a significant reduction in ReHo and DC among MS patients, especially in regions of the CEN and SN, indicating impaired local and global connectivity. Conversely, ALFF was found to be elevated in certain CEN regions in MS patients, which may reflect compensatory hyperactivity in response to network disruptions. Notably, the salience network exhibited consistent reductions across all three measures, suggesting widespread functional impairment in brain regions responsible for integrating and prioritizing stimuli. Conclusion These findings highlight the utility of rs-fMRI in detecting subtle but meaningful changes in brain function that are not always apparent through structural imaging. The study contributes to a growing body of evidence supporting the role of triple-network dysfunction in MS and reinforces the potential of functional imaging markers in the early diagnosis, clinical monitoring, and personalized treatment planning for patients with MS