What the doctor is trying to detect is if the prostate cancer has metastasized. If it has that will change the treatment plan. It might be a local spread to seminal or lymph nodes or more distal if anything is found. The doctors grading the test know where accumulations occur such as bladder that are not cancer. Actually, the PSMA is more likely to have a miss than a false positive. Since it is a scan from neck to mid-thigh they will report on any other abnormal or benign items they find. The grade group is always the highest one. Group 3 is a 4+3 which means that over 50% was Gleason type 4. Other factors would be how high your PSA was. Was anything else mentioned in the biopsy (EPI, Cribform, etc.) that indicates a more aggressive cancer.

Almost everyone with group 3 or above has had a PMSA PET scan if diagnosed in the last few years. It takes about 2 hours with the first hour waiting after the injection and about 20 minutes of actual scan.