Thirty six patients, who have suspicion of recurrent prostate cancer after definitive therapy such as radiotherapy, will be recruited into this study. At least half of the patients will have positive imaging findings and will undergo 2D TRUS-guided biopsy as well as PET/ultrasound fusion biopsy. The proposed study will be the first-in-human trial that uses PET/CT imaging to direct 3D ultrasound-guided biopsy of the prostate. The multimodality imaging approach will combine the high sensitivity from PET and real-time information from ultrasound for improved cancer detection.