Leveraging the preclinical evidence and clinical experience with MRgFUS BBB opening in human subjects, the investigators propose a phase I open-label study to determine the safety and feasibility of three biweekly delivery of Cerezyme (an analogue of the human enzyme beta-glucocerebrosidase) via MRgFUS induced BBB opening to unilateral putamen in PD. The putamen contains terminals of dopaminergic neurons from the substantia nigra, and is a critically affected brain region in PD. The primary objective is to determine the feasibility of repeated MRgFUS BBB opening for Cerezyme delivery in unilateral putamen. The secondary objective is to describe the safety and tolerability of the procedure. Another objective is to measure changes in PD relevant clinical scores and Cerezyme relevant biomarkers in the study.