The Role of Transrectal Power Doppler Ultrasonography in the Detection of Prostate Cancer

Objective: This study aimed to evaluate the clinical utility of power Doppler ultrasonography (PDUS) in the detection of prostate cancer and determine its predictive ability compared to digital rectal examination, serum PSA levels and gray-scale transrectal ultrasonography, using biopsy as the reference standard. Materials and Methods: This is a prospective cross-sectional study of 100 consecutive patients, who underwent prostate needle biopsies at the National Kidney and Transplant Institute. All patients were seen at the Out-patient Department, suspected of having prostate cancer because of abnormally high serum PSA levels (>4 ng/ml) and/or abnormal digital rectal examination. Patients previously diagnosed with prostate cancer were excluded in the study. All patients underwent gray-scale TRUS before power Doppler imaging of the prostate using the Siemens Sonoline Elegra high resolution digital ultrasound with a 6.5 MHz endocavitary probe. After power Doppler imaging, a systematic 12-core and lesion-directed TRUS-guided biopsy of the prostate was performed. Results: A total of 100 patients (mean age 65, SD 7, range 41-83) were included in this study. Prostate needle biopsy confirmed 37 prostate cancer cases. Of the 37 patients diagnosed with prostate cancer, 18 had an abnormal DRE, 26 had abnormal TRUS findings, and 14 had positive power Doppler flow. PDUS has a positive predictive value of 66.7% and a specificity of 88.9%. Logistic regression analysis with the odds ratio computed at 95% C.I. showed that the probability of having prostate cancer when DRE is positive, PSA is elevated, hypoechoic lesion is present on Gray-scale TRUS and hypervascularity of the peripheral zone is present on PDUS are significantly higher than if all of these tests were negative with PDUS in combination with DRE showing the highest predictive ability for prostate cancer. Conclusion: Power Doppler imaging increases the specificity and positive predictive value of Gray-scale transrectal ultrasound in prostate cancer detection. The addition of PDUS to the screening tool of digital rectal exam increases the probability of the patient having cancer when both tests are positive, thus increasing its predictive power.