High-frequency Doppler US of the prostate: Effect of patient position

PURPOSE: To evaluate cancer detection with directed biopsy of the prostate on the basis of high-frequency Doppler ultrasonographic (US) findings, and to determine the effect of patient position on the observed flow pattern. MATERIALS AND METHODS: Thirty-two patients were evaluated in the left lateral decubitus position with gray-scale, color Doppler, and power Doppler transrectal US. Up to four directed biopsy specimens were obtained on the basis of gray-scale and Doppler US findings, and modified sextant biopsy followed. Analysis of variance and the Wilcoxon signed rank test were used to evaluate the distribution of Doppler signals within the prostate. Three healthy volunteers with no known prostate disease were also examined in supine and both decubitus positions. RESULTS: In the patient group, both color and power Doppler US demonstrated increased flow on the left side of the prostate, with greater flow toward the base of the gland (P < .002). Consequently, 62 of 90 directed-biopsy cores were obtained in the left base and midgland. The positive biopsy rate for directed biopsy was not significantly different from that of sextant biopsy (P = .4). Seven patients had cancer that was identified with sextant biopsy, but only four cancers were identified with directed biopsy. Each of the three healthy volunteers demonstrated increased Doppler flow on the dependent side when the subject was in the lateral decubitus position. CONCLUSION: The positive yield of directed biopsy was similar to the yield of sextant biopsy. On the basis of observations made in healthy volunteers, the authors conclude that flow asymmetry in patients who underwent biopsy may have been related to patient position.