Clinical efficacy of prostate cancer detection using power doppler imaging in American and Japanese men

PURPOSE: The aim of this study was to compare the detection rates of tumor vascular flow as measured by power Doppler imaging (PDI) in 2 populations and to determine whether PDI can reduce the number of unnecessary prostate biopsies in men with serum prostate-specific antigen (PSA) concentrations less than 10.1 ng/ml. METHODS: The patient populations were Japanese (group 1) and American (group 2) men with either serum PSA concentrations of 4.1-10.0 ng/ml or abnormal findings on digital rectal examination (DRE) plus PSA concentrations less than 4.1 ng/ml. We compared the overall diagnostic accuracy of DRE, gray-scale transrectal sonography (TRUS), and PDI between the 2 groups. RESULTS: In total, 275 men were studied, 154 in group 1 and 121 in group 2. Cancer was identified in 27% of men in group 1 and in 60% of group 2. Men with cancer in both groups differed significantly in age, peripheral zone volume, and mean number of positive biopsy cores. The sensitivity and specificity of PDI in group 2 were significantly inferior to those in group 1. The negative predictive value (NPV) of PDI was significantly higher for group 1 than for group 2. The NPV of PDI in group 1 was equivalent to that for the combination of DRE and TRUS, whereas the NPV for PDI in group 2 was significantly inferior to that of DRE and TRUS.CONCLUSIONS: Tumor vascularity could be detected by PDI more effectively in Japanese men with cancer than in American men with cancer. We hypothesize that this difference was a result of larger cancer volumes and smaller prostates in the Japanese men. PDI did not provide any performance advantage over DRE and TRUS in avoiding unnecessary biopsies.