RecruitingDiagnostic testClinical Translation of a Novel Brain PET Insert for Simultaneous PET/MRThe primary goal of this project is to study the feasibility of a brain-dedicated PET insert for an MR scanner for simultaneous acquisition of PET/MR images of human brains. The study will also allow us to compare the imaging performance of the investigator's brain-dedicated PET insert against a commercial whole-body permanently integrated PET/MRI system using a common radiopharmaceutical.