Despite declining enthusiasm within the urology community, ultrasound remains a useful tool for evaluation of the prostate and diseases that affect the gland, New York radiologist Matthew Rifkin said at an RSNA refresher course on genitourinary ultrasound.

"Ultrasound is a much better tool than many of my urologic colleagues feel," said Rifkin, a professor of urology at the State University of New York at Stony Brook.

Ultrasound remains the standard imaging tool for evaluation of benign prostatic hyperplasia. Though far from perfect, ultrasound also makes important contributions to the diagnosis and management of prostate cancer. And the modality provides useful information about prostatitis and other inflammatory conditions affecting the prostate.

With respect to prostate cancer, only 25% to 30% of lesions seen on ultrasound prove to be cancerous. The positive yield is higher for hyperechoic lesions (35% to 40%) than for nonhyperechoic lesions (10% to 15%). Conditions that can confound ultrasound evaluation of the prostate include chronic inflammation, fibrosis, old infarcts, and calcifications, all of which have features that can be mistaken for cancer.

Augmentations to ultrasound can help improve the technology's ability to evaluate the prostate. Potentially useful tools include color Doppler, contrast enhancement, use of 3-D imaging, and increased power. As an example of the contributions of contrast enhancement, Rifkin cited an evaluation of 65 patients with prostate lesions, 22 of which proved to be cancerous. In three cases, the cancer could be identified only by use of color Doppler with contrast.

Color should be used as an adjunct to gray-scale analysis, Rifkin said. Contrast enhancement is especially useful for detecting flow abnormalities, and 3-D ultrasound provides more information than 2-D imaging about the gland's physical configuration and its relationship to its internal and external environment.

Definitive diagnosis of prostate cancer still requires a biopsy. Ultrasound guidance remains the standard for obtaining pathologic specimens. CT guidance continues to have its supporters, but the technology does not do a good job of defining areas of abnormality, Rifkin said.

No optimal imaging technique has emerged for prostate cancer staging. Ultrasound and CT have demonstrated little utility for staging. MRI has proven useful for evaluation of the subpopulation of men who have clearly elevated levels of prostate-specific antigen, in the range of 10 to 20 ng/mL. Ultrasound has also demonstrated some value for follow-up evaluation of patients after radical prostatectomy. Again, use of techniques such as contrast enhancement and color can help identify residual cancer or pick up recurrences.

Ultrasound has proved especially useful for evaluation of prostatitis that is refractory to antibiotics. The imaging modality can also identify prostatic abscesses and areas of extraprostatic involvement.