[Assessment of prostatic weight by means of computed tomography and urethroscopy]

Preoperative determination of prostatic weight in patients with prostatic hyperplasia is important in determining the choice of the surgical technique used. Prostatic volume determination with CT scans, using the ellipsoid formula, appears to be quite accurate. CT scanning of the prostate gland was performed in 34 patients with prostatic hyperplasia (2 cases with cancer). All scans were performed with a Toshiba TCT-60A-30 scanner, and were made for 10 mm slices as follows. From the CT image the maximum transverse diameter (a) sagittal diameter (b), and the maximum transverse area (S) were easily determined. The long axis was calculated from the bladder neck to the distal edge of the vermontanum by urethroscopy (Fig.1). A rough calculation was given by formula V1 or V2. V1 = pi abc/6 or V2 = 2/3 Sc. Calculated volumes of the prostate were compared with the weight of surgical specimens (TUR-P 27 cases, open surgery 7 cases). A good correlation was obtained by this method, i.e., regression equation V1: y = 1.21x + 9.68 (gamma = 0.9376); V2: y = 1.31x + 10.58 (gamma = 0.9471). This method is considered valuable for preoperative measurement of prostatic size, and is useful when evaluating changes in prostatic volume during non-surgical treatment.