Induced current effects on functional magnetic resonance imaging interpretability during monopolar deep brain stimulation

MRI-induced current substantially alters the effective output of monopolar DBS, introducing uncertainty into any concurrent fMRI acquisition. Although functional imaging was not directly performed in human subjects, these findings imply that the observed blood oxygen level-dependent (BOLD) response during monopolar stimulation likely reflects the distorted, not programmed, stimulation. Bipolar configurations avoid this confounder and should be preferred when interpreting fMRI data acquired during DBS.