Quantitative susceptibility mapping to predict deep brain stimulation outcomes in persons with Parkinson’s disease

Abstract BACKGROUND: Brain regional mineralization, assessed by quantitative susceptibility mapping (QSM), is an emerging biomarker for disease progression in Parkinson’s disease (PD). OBJECTIVES: To study the association of regional QSM values with changes in quality of life (QOL) and motor and nonmotor symptoms 6 months after subthalamic nucleus deep brain stimulation (STN-DBS) in PD. METHODS: We recruited 20 persons with PD undergoing bilateral STN-DBS and measured preoperative QSM values at the following regions of interest (ROI): motor cortex (M1), caudate (CAUD), globus pallidus interna (GPi), putamen (PUT), STN, substantia nigra (SN), and dentate nucleus (DN). We correlated the QSM parameters with changes in the PD Quality of Life questionnaire, motor symptoms (Unified Parkinson’s Disease Rating Scale [UPDRS]), and nonmotor symptoms 6 months after surgery. RESULTS: Brain iron deposition was highest in the SN, followed by the STN, GPi, dentate, PUT, caudate, and M1. There was no correlation between QSM values at any ROI and changes in QOL at 6 months [M1, p = 0.574; CAUD, p = 0.135; GPi, p = 0.833; PUT, p = 0.560; STN, p = 0.514; SN, p = 0.271; DN, p = 0.715). We noted trends toward a correlation between increasing CAUD mineralization and less improvement in QOL (r = 0.664, p = 0.021), increasing STN mineralization and less improvement in Hospital Anxiety And Depression Scale-Anxiety (rho = −0.588, p = 0.013), and increasing DN mineralization and less improvement in UPDRS total OFF (rho = −0.523, p = 0.018). Persons with postoperative freezing of gait had higher baseline STN QSM values (p = 0.041). CONCLUSION: In this study, regional QSM values did not predict changes in QOL or motor and nonmotor outcomes after STN-DBS in PD. However, certain trends toward region-specific mineralization being associated with specific motor or nonmotor symptoms were observed.