A Comparative Study for Estimation of Prostatic Volume with Ultrasonography and Computerized Tomography

Shim, Bong Suck; Kwon, Sung Won

Abstract

Preoperative estimation of the volume of the prostatic gland is essential in making a decision whether to perform an open prostatectomy or a transurethral resection. But the shape of the prostate can not be revealed by X-ray because of its locational and anatomical characteristics. Several types of examinations, such as cystourethrography, cystoscopy, rectal palpation, are of value as descriptive macroscopic diagnostic methods but they can only indirectly procure representation of the prostate. Recently the anatomic structure of the prostate is visible in the form of an easily comprehensible cross sectional picture with ultrasonography and CT, which are new diagnostic, methods. Anatomical detail and cross-sectional format of ultrasonography and CT can clarify the boundary of the prostate and the relationship of the intrapelvic organs. Previously in our Department of Urology, Suprapubic ultrasonographic evaluation of the prostate had been reported and this time, we performed ultrasonography and CT simultaneously in 19 patients with BPH and 8 patients with prostatic carcinoma. And then the prostatic volume on the preoperative ultrasonographic and CT estimation were compared with the volume of the postoperative resected prostate. The following results were obtained: 1. There was no difference on the ultrasonographic and CT features of the prostate in the patients with BPH. BPH showed symmetric , round and oval shape, smooth margin and homogenous fine density within the prostate. Early prostatic carcinoma showed relatively asymmetric shape and inequal density Advanced carcinoma showed markedly irregular margin and infiltration to bladder wall and seminal vesicle. 2. The most part of the estimated prostatic volume was in 36.07-65.42 cc as 15 cases (55.6%) on ultrasonography and 16 cases (59.3%) on CT. 3. The mean prostatic volume of 19 patients with BPH was 4.44+/-0.47 cm (47 39+/-14.67 cc)- mean transverse diameter+/-standard deviation (mean volume+/-standard deviation) on ultrasonographic estimation and 4.63+/-0.46 cm (53.57+/-16. 12cc) on CT estimation. 4. The mean prostatic volume of 19 patients with prostatic carcinoma was 5.05+/-0.4 cm (68.64+/-15.1 cc) on ultrasonographic estimation and 4.96+/-0.35 cm (64.91+/-13.52 cc) on CT estimation, and it showed larger than that of 19 patients with BPH. 5. Through the comparative studies between the prostatic volume on the preoperative ultrasonographic and CT estimation and postoperative volume of the enoculated prostate, ultrasonographic estimation showed mean error rate 20.47+/-11.32%, correlation coeffcient 0.92(P<0.01) and CT estimation showed mean error rate 9.61+/-3.84%, correlation coeffcient 0.98(P<0.005). And so judging from the above result, CT was more accurate on preoperative estimation of the prostatic volume than ultrasonography.