Neuromelanin Change in the Substantia nigra for Differentiating Multiple System Atrophy from Parkinson’s Disease

Motivation: Multiple system atrophy (MSA) and Parkinson’s disease (PD) are sharing many common clinical presentations. The clinical diagnosis has been empirical due to a lack of a subjective imaging biomarker. Goal(s): To investigate possible NM change in the SN and to better facilitate differential diagnosis. Approach: 38 MSA , 38 PD patients and 38 HCs were scanned on a 3T MRI system. We calculated the relative contrast ratio (rCR) and NM volume of bilateral SN. Results: HCs had higher rCR and NM volume than patients with PD and MSA (p＜0.001). Of note, patients with MSA had lower NM volume than patients with PD (p＜0.001). Impact: Our finding suggests that NM degeneration and depigmentation of SN may be more severe in patients with MSA in comparison with PD. Hence, NM measures of the SN may provide promising insight into differentiating MSA and PD.