Functional impact of subthalamotomy by magnetic resonance-guided focused ultrasound in Parkinson's disease: a hybrid PET/MR study of resting-state brain metabolism

Purpose Subthalamotomy using magnetic resonance-guided focused ultrasound (MRgFUS) has become a potential treatment option for the cardinal features of Parkinson's disease (PD). The purpose of this study was to evaluate the effects of MRgFUS-subthalamotomy on brain metabolism using different scale levels. Methods We studied resting-state glucose metabolism in eight PD patients before and after unilateral MRgFUS-subthalamotomy using hybrid [F-18]FDG-PET/MR imaging. We used statistical nonparametric mapping (SnPM) to study regional metabolic changes following this treatment and also quantified whole-brain treatment-related changes in the expression of a spatial covariance-based Parkinson's disease-related metabolic brain pattern (PDRP). Modulation of regional and network activity was correlated with clinical improvement as measured by changes in Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor scores. Results After subthalamotomy, there was a significant reduction in FDG uptake in the subthalamic region, globus pallidus internus, motor and premotor cortical regions, and cingulate gyrus in the treated hemisphere, and the contralateral cerebellum (p <0.001). Diffuse metabolic increase was found in the posterior parietal and occipital areas. Treatment also resulted in a significant decline in PDRP expression (p <0.05), which correlated with clinical improvement in UPDRS motor scores (rho = 0.760; p = 0.002). Conclusions MRgFUS-subthalamotomy induced metabolic alterations in distributed nodes of the motor, associative, and limbic circuits. Clinical improvement was associated with reduction in the PDRP expression. This treatment-induced modulation of the metabolic network is likely to mediate the clinical benefit achieved following MRgFUS-subthalamotomy.