The role of transrectal ultrasound in diagnosing prostate cancer.

The availability of the prostate-specific antigen test to screen for prostate cancer has caused a significant workload burden for urologists and radiologists alike. Prostate cancer is common in our aging population and most cancers are now definitively detected by transrectal ultrasound (TRUS)-guided prostatic needle biopsy. TRUS alone has limited potential to identify prostatic cancer because of frequent multifocality of cancer within the prostate, the variable sonographic appearance of prostatic tumors, the poor specificity of focal ultrasonic abnormalities, and the substantial percentage of isoechoic prostate cancers (which cannot be differentiated from adjacent benign tissues with imaging). Developments in TRUS equipment over the past decade include the use of color and power Doppler, higher frequencies, broad bandwidth technologies, and harmonic, contrast harmonic, and pulse inversion imaging. All of these improvements may enhance detection of subtle focal sonographic abnormalities within the prostate. Ultrasonic contrast agents can aid the visualization of subtle alterations in prostatic echotexture by highlighting changes in microvasculature. It is possible that Doppler techniques and contrast agents have the potential to reveal prognostic information about cancer in individual patients.