Correlation of transrectal ultrasound imaging and the results of systematic biopsy with pathological examination of radical prostatectomy specimens.

OBJECTIVE

To determine the usefulness of transrectal ultrasound (TRUS) and systematic biopsy by correlating these results with pathological findings after radical prostatectomy.

PATIENTS AND METHODS

Pre-operative TRUS examination combined with the findings on systematic biopsy in 15 patients (mean age 70.6 years, range 57-87) who underwent radical prostatectomy between October 1992 and February 1994 were compared retrospectively to the histological features of whole mount sections of the surgical specimens.

RESULTS

In all cases, the tumour was visualized as a hypoechoic area on the sonogram. In addition, in six of 15 cases the tumour was localized in an isoechoic area which was examined before the operation by systematic biopsy. In this series, a systematic biopsy before operating detected tumour grade and localization of the tumour in 14 and 15 patients, respectively. The positive predictive value of capsular penetration and seminal vesicle invasion on the sonogram was 0.71 and 1.00, respectively, while sensitivity was 1.00 and 0.33, respectively. Five of seven patients with findings of capsular penetration on the sonogram revealed capsular penetration in the resected prostate, whereas, of three patients with pathologically detected seminal vesical invasion, only one had findings of seminal vesicle invasion by ultrasonography. The serum prostate specific antigen level of all three patients was more than 30 ng/mL. Moreover, in this series of 15 patients TRUS detected the precise stage in 11 patients. In the remaining four patients, two were overstaged and two were understaged. Tumours with hypoechogenicity were of higher grade and larger than tumours with isoechogenicity. All tumours with hypoechogenicity were palpable and all with isoechogenicity were not.

CONCLUSIONS

TRUS combined with a systematic biopsy was useful in predicting tumour grade, exact location and capsular penetration. However, it was not useful for determining tumour stage or predicting seminal vesicle invasion of prostate cancer. TRUS-guided seminal vesicle biopsy must be performed in patients with a serum prostate specific antigen of more than 30 ng/mL.