The Application Value of Prostate Specific Membrane Antigen PET/CT in Biopsy Free of PSA Grey Area Prostate Cancer

The goal of this observational study is to establish an evaluation system for accurate identification of prostate cancer and clinical significant prostate cancer in patients in the PSA gray zone. The main questions it aims to answer are: proportion of men who could have avoided biopsy with positive PSMA-PET and no clinically significant cancer detected on biopsy. Participants will: 1. undergo PSMA PET/CT and multiparametric MRI; and 2. undergo prostate biopsy Researchers will compare the diagnostic performance of PSMA PET/CT and multiparametric MRI for prostate cancer and clinical significant prostate cancer to see if there are differences.

Prostate Specific Antigen (PSA) is a serine protease secreted by prostate epithelial cells, which is a tumor marker of prostate cancer. At present, PSA\<4 ng/ml is considered as the normal value, and PSA 4-10 ng/ml is considered as the gray value. PSA\>10 ng/ml should be highly suspected of prostate cancer. Prostate biopsy is still the gold standard for the diagnosis of prostate cancer. However, as an invasive procedure, it can cause many complications such as pain, bleeding, lower urinary tract symptoms and infection. There is a growing trend to reduce unnecessary prostate biopsies. Prostate specific membrane antigen (PSMA) is a membrane-bound enzyme that is highly expressed in more than 90% of prostate cancer lesions and has become an important target for molecular imaging of prostate cancer. In recent years, radioactive nuclide 18F labeling targeting PSMA positron emission tomography/computed tomography (PET/CT) has shown important clinical application value in prostate cancer recurrence monitoring. The goal of this observational study is to establish an evaluation system for accurate identification of prostate cancer and clinical significant prostate cancer in patients in the PSA gray zone. Participants will: 1. undergo PSMA PET/CT and multiparametric MRI; and 2. undergo biopsy Researchers will compare the diagnostic performance of PSMA PET/CT and multiparametric MRI for prostate cancer and clinical significant prostate cancer to see if there are differences.