Participants with clinically localized, unilateral high grade prostate cancer (Gleason score 7-10 prostate cancer localized to one lobe on prior biopsies) OR at high risk for having unrecognized high grade prostate cancer (overall Gleason score 6 with > half of systematic biopsy cores positive and > 50% of core involvement in at least one core), interested in HIFU would receive both a standard mpMRI and 18F-fluciclovine PET-hrMRI.