Quantitative Susceptibility Mapping Changes Relate to Gait Issues in Parkinson’s Disease

ABSTRACT: Background: Quantitative susceptibility mapping (QSM) demonstrates elevated iron content in Parkinson’s disease (PD) patients within the basal ganglia, though it has infrequently been studied in relation to gait difficulties including freezing of gait (FOG). Our purpose was to relate QSM of basal ganglia and extra-basal ganglia structures with qualitative and quantitative gait measures in PD. Methods: This case–control study included PD and cognitively unimpaired (CU) participants from the Comprehensive Assessment of Neurodegeneration and Dementia study. Whole brain QSM was acquired at 3T. Region of interests (ROIs) were drawn blinded manually in the caudate nucleus, putamen, globus pallidus, pulvinar nucleus of the thalamus, red nucleus, substantia nigra, and dentate nucleus. Susceptibilities of ROIs were compared between PD and CU. Items from the FOG questionnaire and quantitative gait measures from PD participants were compared to susceptibilities. Results: Twenty-nine participants with PD and 27 CU participants were included. There was no difference in susceptibility values in any ROI when comparing CU versus PD ( p > 0.05 for all). PD participants with gait impairment ( n = 23) had significantly higher susceptibility in the putamen ( p = 0.008), red nucleus ( p = 0.01), and caudate nucleus ( p = 0.03) compared to those without gait impairment ( n = 6). PD participants with FOG ( n = 12) had significantly higher susceptibility in the globus pallidus ( p = 0.03) compared to those without FOG ( n = 17). Among quantitative gait measures, only stride time variability was significantly different between those with and without FOG ( p = 0.04). Conclusion: Susceptibilities in basal ganglia and extra-basal ganglia structures are related to qualitative measures of gait impairment and FOG in PD.