A Multi-sequence MRI Study in Parkinson's Disease: Association Between Rigidity and Myelin

Area of Science:

• Neuroimaging
• Neurology
• Biomedical Engineering

Background:

• The underlying mechanisms of rigidity in Parkinson's disease (PD) remain unclear.
• Advanced brain Magnetic Resonance Imaging (MRI) techniques offer potential insights into the origins of PD symptoms.

Purpose of the Study:

• To investigate the combined and distinct relationships between functional and structural MRI measures and clinical features of PD.
• To specifically explore the association of MRI markers with rigidity in Parkinson's disease.

Main Methods:

• A retrospective cross-sectional study involving 31 PD patients.
• Utilized multi-sequence MRI, including diffusion-weighted and resting-state functional MRI, on a 3T scanner.
• Assessed myelin water fraction (MWF), fractional anisotropy (FA), and functional connectivity, correlating these with motor and non-motor symptoms using multiset canonical correlation analysis (MCCA) and canonical correlation analysis (CCA).

Main Results:

• MCCA identified a joint component linking MWF, FA, and functional connectivity to age, bradykinesia, cognition, depression, and apathy, but not rigidity or tremor.
• Following adjustment for this joint component, CCA revealed a unique association between MWF and rigidity.
• No unique associations were found between FA or functional connectivity and rigidity.

Conclusions:

• Multi-sequence MRI markers like MWF, FA, and functional connectivity can characterize various PD symptoms.
• Rigidity in Parkinson's disease is uniquely associated with widespread myelin alterations, suggesting a specific pathophysiological basis.