Current Neuroimaging Modalities to Distinguish Parkinson's Disease from its Mimics: Imaging Features and Implications...

Parkinson's disease (PD) is a chronic progressive neurodegenerative disorder characterized by tremors, rigidity, and bradykinesia. This is primarily attributed to loss of nigrostriatal dopaminergic neurons to varying degrees. Many conditions that present similar classic motor symptoms of PD, known as atypical parkinsonian syndromes (APS), have also been identified. These encompass multiple system atrophy (MSA), progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB), and corticobasal degeneration (CBD). On the other hand, causes of non-neurodegenerative parkinsonism include vascular parkinsonism, drug-induced parkinsonism, and essential tremors. Neuroimaging plays a significant role in discriminating PD from its mimics which may represent a significant challenge in clinical practice. This article aims to review recent developments in imaging technologies, particularly magnetic resonance imaging (MRI) and nuclear medicine imaging techniques, that have the potential to unravel characteristic morphological and metabolic changes in the brain and would aid in the early diagnosis of PD and its differentiation from its potential mimickers.Learning objectivesTo identify the peculiar structural imaging features of atypical parkinsonian syndromes and recognize the role of the current state-of-the-art neuroimaging modalities (particularly MRI and nuclear medicine techniques) in discriminating Parkinson's disease from its mimics.