Magnetic resonance parkinsonism index in progressive supranuclear palsy and vascular parkinsonism.

To investigate accuracy of the magnetic resonance parkinsonism index (MRPI) in differentiating progressive supranuclear palsy (PSP) from vascular parkinsonism (VP). We retrospectively analyzed radiological data of 12 PSP patients and 17 VP patients group-matched by age and sex who performed a standardized brain magnetic resonance imaging (MRI). Analysis of selected structures morphometry was performed to all study subjects and the MRPI was calculated for each selected patient. MRI midbrain area as well as superior cerebellar peduncle width were significantly lower in PSP patients compared to VP subjects. MRPI was significantly larger in PSP patients compared to VP subjects. MRPI value ≥13 distinguished the two groups with a sensitivity of 100 % (95 % CI 69.9-100) and a specificity of 100 % (95 % CI 77.1-100). MRPI may represent an accurate tool in differentiating PSP from VP.