Contrast-enhanced transrectal ultrasound for assessing vascularization of hypoechoic BPH nodules in the transition and peripheral zones: comparison with pathological examination.

The purpose of this study was to investigate the vascularization of zonal location of hypoechoic benign prostatic hyperplasia (BPH) nodules and to evaluate the clinical value of contrast-enhanced transrectal ultrasound (CETRUS) for assessing vascularity of hypoechoic BPH nodules. Sixty-two patients with hypoechoic biopsy-proven BPH nodules in transition zone (TZ) (32 patients) or peripheral zone (PZ) (30 patients) of the prostate gland underwent CETRUS examination between January 2006 and September 2006. The enhancement characteristics of hypoechoic BPH nodules were observed and time to enhancement (AT), time to peak intensity (TTP) and peak intensity (PI) were measured with ACQ time-intensity curve analysis software. In addition, microvessel density (MVD) and vascular endothelial growth factor (VEGF) immunoreactivity were determined in the biopsy specimens. Microvessels were identified by immunohistochemical staining of endothelial cells for CD34. Findings were compared between hypoechoic BPH nodules located in PZ and TZ. The most common enhancement characteristic of hypoechoic BPH nodules in PZ was nonenhanced area inside (21/30), while most of hypoechoic BPH nodules in TZ appeared homogeneous enhancement (28/32). The average AT and TTP were significantly longer, the average PI was significantly lower in hypoechoic BPH nodules located in PZ than TZ (p < 0.01). The VEGF expression and MVD were significantly higher in hypoechoic BPH nodules located in TZ than PZ (p < 0.01). PI was found to be an important parameter strongly correlated with degree of vascularity of hypoechoic BPH nodules. Hypoechoic BPH nodules located in PZ and TZ showed significant difference in vascularization, which indirectly verified our finding that BPH nodule could occur in the peripheral zone. CETRUS could afford information on the vascularity of hypoechoic BPH nodules in a noninvasive manner and this could be used to improve selection of nodules for biopsy.