Quantitative MRI measurement of superior cerebellar peduncle in progressive supranuclear palsy

Background: Postmortem studies have shown atrophy of the superior cerebellar peduncle (SCP) to distinguish progressive supranuclear palsy (PSP) from other neurodegenerative diseases. It is not clear whether MRI-based measurements can differentiate this relative atrophy of the SCP during life. Methods: Volumetric MRI was acquired prospectively in 53 subjects: 19 with PSP, 10 with multiple system atrophy (MSA), 12 with Parkinson disease (PD), and 12 healthy controls. SCP volume was assessed by detailed quantitative volumetric measurement and independently by blinded visual rating of SCP atrophy. Results: The mean SCP volume, corrected for total intracranial volume, was lower in patients with PSP than controls (p < 0.001), patients with MSA (p = 0.001), and patients with PD (p = 0.003). There was an overlap between individual SCP volume measurements in the PSP subjects and the other groups. Neuroradiologic rating correctly identified PSP cases based on the presence of SCP atrophy with a sensitivity of 74% and a specificity of 94%. Conclusions: The authors propose that together with other radiologic features of progressive supranuclear palsy (PSP) such as midbrain atrophy, a visual assessment of the superior cerebellar peduncle may help increase the clinical diagnostic accuracy in PSP.