Objective: With 7T MRI, we aimed to study the relationship between the initial motor phenotype of Parkinson’s disease (PD) and normal-sized PVSs (nPVSs) burden in basal ganglia, thalamus, midbrain and centrum semiovale.

Background: More evidence has indicated that changes in perivascular spaces (PVSs) in basal ganglia are related to motor symptoms and cognitive changes in PD. However, the correlation between the initial motor phenotype and PVSs distribution and burden in PD freezing of gait (FOG) remains unclear. In addition, limited by low-resolution images, previous studies have mainly focused on enlarged PVSs. nPVSs are typically invisible due to small size in the range of 0.13-0.96 mm, and have not been well-studied. With increased spatial resolution and signal-to-noise ratio, 7T MRI increases the detection of nPVSs. The 7T sequences have been optimized to provide detailed assessment of distributions of nPVSs in the white matter and subcortical nuclei.

Method: In this pilot study, 10 PD patients without FOG (FOG-), 20 PD patients with FOG, 10 tremor dominant, FOG(TD), and 10 non-TD type, FOG(TD-), along with 10 healthy controls were recruited. The numbers and volume of nPVSs were assessed with 7T MRI. Correlations between the nPVS number and burdens and clinical features (UPDRS, cognition, New FOG questionnaire, Hamilton Depression and Anxiety Scale, levodopa equivalents daily dose) were further analyzed.

Results: 7T MRI can reliably assess nPVSs. The nPVS burden of bilateral and right basal ganglia were significantly higher in PD freezers. With subgroup analysis, a significantly negative correlation existed between the tremor score and basal ganglia nPVSs count, and a positive correlation was found between the levodopa equivalent daily dose and nPVSs count of basal ganglia.

Conclusion: The nPVS in basal ganglia may contribute to the progression to FOG in PD patients, but the distribution and burden of nPVS may differ in people with or without tremor as initial motor presentation. High resolution 7T MRI is a sensitive and reliable tool to evaluate basal ganglia nPVS, and may be a useful imaging marker for predicting gait impairment that may evolve into FOG in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/normal-sized-perivascular-space-in-basal-ganglia-related-to-motor-phenotypes-in-parkinson-freezers/