The radiologist will read the scan..and that should not be more than several days. I had an increase in PSA over the years and requested a PET scan. As you know, the PET scan uses a radioactive elements which is injected into the blood stream. Medically, the cancer, if any, if high in protein nodules and shows up like a "match" in a dark room. The higher the "light" the more intense the cancerous portion of the prostate is.. The PET scan will absolutely validate yes or not as to prostate cancer.