Are cerebral perfusion and atrophy linked in multiple sclerosis? Evidence for a multifactorial approach to assess neurodegeneration

Background: Grey Matter (GM) atrophy has been extensively described in Multiple Sclerosis (MS) patients, while cerebral hypoperfusion has been less consistently reported. Since hypoperfusion might be related to atrophy, we evaluated the presence of both damages. Objective: We aimed to assess if the regions of altered perfusion and atrophy overlapped with one another and if the two parameters were locally related. Method: 3D-T1 weighted and arterial spin labelling sequences were acquired using a 1.5T Magnetic Resonance Imaging scanner from 26 relapsing remitting MS patients and 26 Healthy Controls (HC). GM volume and Cerebral Blood Flow (CBF) differences and their correlation were tested with a voxel-wise approach. Results: MS patients (41.4±12.5 years; 14 females) had a median [25th-75th percentile range] Expanded Disability Status Scale of 1.0[1.0-2.4] and a median [25 th -75 th percentile range] disease duration of 8.0 [4.0-16.5] years. HC were age- and sex-matched (43.9±17.4 years; 11 females). GM atrophy was detected for MS group in the right parahippocampal gyrus, thalami and left caudate (pFWE≤0.05). Areas of significant (after family-wise error -FWE- correction for multiple comparisons) (pFWE≤0.05) hypoperfusion were found for MS in the anterior cingulate and paracingulate gyri, supplementary motor cortex, precentral and superior frontal gyrus. GM volume and CBF showed a significant correlation (pFWE≤0.05) in the right lateral occipital cortex and precuneus in the MS group. Conclusions: GM atrophy and hypoperfusion in MS were located in different areas. Perfusion estimate might be used as a further marker of tissue damage, in addition to GM volume.