Correlation of MRI Markers with Clinical Features in Multiple System Atrophy.

BACKGROUND AND PURPOSE: MSA is a progressive neurodegenerative disorder with two main subtypes: MSA with predominant cerebellar ataxia (MSA-C) and MSA with predominant parkinsonism (MSA-P). The latest diagnostic criteria emphasize the importance of neuroimaging markers from MRI alongside clinical symptomatology assessment. This study investigates the relationship between visual MRI markers and multiple system atrophy (MSA) subtypes, clinical features, and cerebral glucose metabolism and striatal dopaminergic degeneration.

MATERIALS AND METHODS: Eighty-nine patients with MSA, 67 with predominant parkinsonism (MSA-P) and 22 with predominant cerebellar ataxia (MSA-C), underwent extensive clinical and neuropsychiatric evaluations and routine MRI scans to assess markers like the hot-cross bun (HCB) sign, putaminal iron deposition, midbrain to pons (M/P) ratio, and cerebellar atrophy. PET imaging with 18F-fluorodeoxyglucose (18F-FDG) and 11C-2β-carbomethoxy-3β-(4-fluorophenyl) tropane (11C-CFT) was performed to evaluate brain metabolism and striatal dopaminergic uptake abnormalities.

RESULTS: Canonical correlation analysis revealed significant associations between clinical symptoms and MRI markers, particularly the HCB sign, M/P ratio, and putaminal iron deposition. The HCB sign and M/P ratio correlated with cerebellar dysfunction, while putaminal iron deposition correlated with parkinsonism severity, particularly in MSA-P. Cerebellar and putaminal metabolism negatively correlated with their respective structural changes. However, putaminal iron deposition showed no significant correlation with striatal dopaminergic uptake.

CONCLUSIONS: Visual MRI markers are crucial for diagnosing MSA and delineating disease subtype and symptom severity. Supratentorial and infratentorial MRI markers reflect the severity of parkinsonism and cerebellar dysfunction, respectively. Putaminal iron deposition reflects the severity of parkinsonism, suggesting that iron deposition plays an important role in the pathophysiological mechanisms contributing to parkinsonism in MSA.