This phase II trial studies how well gallium Ga 68-labeled gastrin-releasing peptide receptor (GRPR) antagonist BAY86-7548 (68Ga-RM2) positron emission tomography (PET)/computed tomography (CT) works in detecting regional nodal and distant metastases in patients with intermediate or high-risk prostate cancer. 68Ga-RM2 PET/CT scan may be able to see smaller tumors than the standard of care CT or magnetic resonance imaging scan.