White matter and cortical changes in atypical parkinsonisms: A multimodal quantitative MR study

Area of Science:

• Neuroimaging
• Neurology
• Radiology

Background:

• Parkinsonism encompasses a group of neurological disorders characterized by movement abnormalities.
• Differentiating between Parkinson's Disease (PD) and atypical parkinsonian syndromes like Progressive Supranuclear Palsy (PSP) and Multiple System Atrophy (MSA) is clinically challenging.
• Advanced Magnetic Resonance Imaging (MRI) techniques offer potential for objective biomarkers.

Purpose of the Study:

• To investigate and compare white matter and cortical alterations in patients with PSP-RS, MSA variants (MSA-C, MSA-P), and PD compared to healthy controls (HC).
• To apply both hypothesis-free and region of interest (ROI)-based advanced MRI analyses.
• To assess the utility of quantitative MRI in the differential diagnosis of parkinsonian syndromes.

Main Methods:

• A cohort of 25 PSP-RS, 9 MSA-C, 9 MSA-P, 47 PD patients, and 27 HC underwent 1.5T brain MRI.
• MRI protocol included high-resolution 3D T1-weighted and diffusion tensor imaging (DTI).
• Analyses included vertex-based cortical thickness, Tract Based Spatial Statistics (TBSS), ROI-based cortical thickness, and probabilistic tractography of the corticospinal tract (CST) and cerebellar peduncles (MCP, SCP).

Main Results:

• PSP-RS showed significant pre-central cortical thinning and diffuse white matter changes across supra- and infratentorial regions.
• PSP-RS exhibited higher mean diffusivity (MD) in the corticospinal tract (CST) within the corona radiata compared to PD and HC.
• MSA-C demonstrated predominant involvement of the middle cerebellar peduncles (MCPs), while MSA-P and PSP-RS showed alterations in MCPs and superior cerebellar peduncles (SCPs), respectively.

Conclusions:

• Distinct patterns of cortical and white matter abnormalities in atypical parkinsonism correlate with specific neuropathological and clinical features.
• Quantitative MRI techniques can detect significant neuroimaging changes relevant to the physiopathology of movement disorders.
• Advanced MRI analysis supports the differential diagnosis of parkinsonian syndromes.