CT Scan, MR Imaging Scan, and Pedal Lymphangiography. Patients with a PSA greater than 25 ng/mL, a Gleason score greater than 6, and a positive DRE should undergo CT scan with FNA of lymph nodes at least 6 mm in size. Otherwise, CT scan, MR imaging scan, and pelvic lymphangiogram are not indicated. This should eliminate use of these staging studies in over 90% of patients with newly diagnosed adenocarcinoma of the prostate. Pelvic Lymph-Node Dissection. Pelvic lymph-node dissection can be safely eliminated in patients who meet the following predictive criteria: 1. PSA not more than 5 ng/mL or 2. Gleason score not more than 5 or 3. A combination of the following: PSA not more than 25 ng/mL, Gleason score not more than 7, and negative DRE. Following these criteria should eliminate the need for pelvic lymphadenectomy in 60% of patients with newly diagnosed prostate cancer.