[Reassessment of the sonographic criterion of prostate cancer--nonspecificity of a hypoechoic lesion].

Of 71 patients who underwent ultrasound guided transrectal needle biopsy at the urology clinic in Kitasato University Hospital 19 (26.8%) patients were found to have prostate cancer. The positive predictive value for transrectal ultrasonography (hypoechoic lesion) was disappointing-only 30% (18/60). While hypoechogenicity has been increasingly accepted as the most sensitive ultrasonographic indicator of malignancy, the specificity of hypoechogenicity is related to benign structures that may also appear hypoechoic. Sonographic detection of prostate cancer is also confounded by the presence of iso- and hyperechoic tumors. Experienced sonographer should be alert to this limitation of the current technology of transrectal ultrasound. The advent of the Biopty gun enabled us to take multiple biopsy cores easily and quickly. Liberal use of random systematic biopsy in addition to directed cores from a hypoechoic lesion should enhance the detection of prostate cancer regardless of the tumor echogenicity.