The importance of measuring the prostatic transition zone: an anatomical and radiological study

Objective To assess the accuracy and reliability of measurements of the vol ume of the transition zone (TZ, representing the hypertrophied benign compo nent) and whole prostate by TRUS in patients with BPH or cancer, by compari ng the radiological with pathological findings after surgery, Patients and methods The study comprised 36 patients with prostate cancer u ndergoing radical prostatectomy and 34 patients with symptomatic BPH treate d using retropubic adenectomy. The weights of the radical prostatectomy spe cimens and of the enucleated adenomas were correlated with the correspondin g volumes of the TZ and of the whole prostate, respectively, measured by TR US using the prolate ellipsoid method. Results The mean (SD) TZ volume measured by TRUS was 36.9 (25.48)mL, wherea s the weight of the enucleated specimen was 42.7 (33.58)g (correlation coef ficient r=0.95, P<0.001). The TRUS estimate of the volume of the whole pros tate was 29.2 (9.24) mt, while the radical prostatectomy specimens weighed 34.5 (10.76)g (r=0.78, P<0.001), The variability in the TZ volume estimate ranged from -17% to +18%, whereas the variability for whole prostate was -2 1% to +30% (P<0.05). Conclusions Measurements of the TZ of the prostate by TRUS are more accurat e than those for the whole prostate, An assessment of the TZ volume may be sufficiently reliable to be used in the clinical management of BPH and to d etect prostate cancer using the prostate-specific antigen density of the TZ as a marker.