The role of magnetic resonance imaging in the diff erential diagnosis of Parkinson’s disease

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases in the world. While until recently MRI was used exclusively for the diagnosis of symptomatic forms of parkinsonism, recent advances in neuroimaging allow the detection of signs of nigral degeneration (MR biomarkers of PD). The article discusses the possibilities of modern MRI modes sensitive to iron (SWI, T2*) and neuromelanin (neuromelanin-sensitive MRI); emphasis is placed on identifying false-negative and false-positive results of the study. The imaging of nigrosome-1 in the dorsal substantia nigra (SN) in MRI-SWI has been discussed since 2013. In the absence of nigral degeneration, this area is defi ned as a hyperintense ovoid area within the dorsolateral border of the hypointense SN (“swallow’s tail” sign). If the optimistic results of the fi rst studies testifi ed to the high sensitivity and specifi city of this technique in PD (the absence of the “swallow’s tail” sign), then in subsequent studies, similar changes were detected in patients with other neurodegenerations with parkinsonism. In addition, the diagnostic value of this technique occurs when using tomographs with a magnetic fi eld strength of at least 3 Tc. Similar conclusions can be drawn about the use of neuromelanin-sensitive MRI, since it is necessary to use high-fi eld magnetic tomographs of 3 Tc or more to detect nigral degeneration, and results similar to PD can also be found in atypical forms of parkinsonism. However, the search for signs of nigral degeneration may be useful in the diff erential diagnosis of PD and non-neurodegenerative disorders. In addition to MRI in the diagnosis of PD, the article discusses neuroimaging in various types of multisystem atrophy, progressive supranuclear palsy, and dementia with Lewy bodies. The article is illustrated with own MRI scans of the brains of patients with PD and other forms of parkinsonism.