Prostate cancer: Contrast-enhanced US for detection

PURPOSE: To assess the detection of prostate cancer with contrast material- enhanced transrectal sonography. MATERIALS AND METHODS: Sixty subjects were examined with conventional gray- scale, harmonic gray-scale, and power Doppler sonography. Evaluation was re peated during intravenous infusion of contrast agent. Gray-scale imaging wa s performed in continuous mode and with intermittent imaging by using inter scan delay times of 0.5, 1.0, 2.0, and 5.0 seconds. Sextant biopsy sites we re scored prospectively as benign or malignant at baseline imaging and agai n during enhanced transrectal sonography. RESULTS: Prostate cancer was present in 37 biopsy sites from 20 subjects. B aseline imaging demonstrated prostate cancer in 14 sites in 11 subjects. En hanced transrectal sonography depicted prostate cancer in 24 sites in 15 su bjects. Each of the five subjects in whom prostate cancer was missed had on ly a single biopsy core with positive findings (Gleason score less than or equal to 6). In three of these five subjects, prostate cancer made up less than 10% of the core. The improvement in sensitivity from 38% (14 of 37 mal ignant foci) at baseline to 65% (24 of 37 malignant foci) with contrast enh ancement was significant (P <.004, McNemar <chi>(2) test). Specificity was similar at baseline (267 [83%] of 323 malignant foci) and during enhanced t ransrectal sonography (257 [80%] of 323 malignant foci). Clustered receiver operating characteristic analysis demonstrated significant improvement in diagnostic accuracy during enhanced transrectal sonography (P=.027). CONCLUSION: Enhanced transrectal sonography improves sensitivity for the de tection of malignant foci within the prostate without substantial loss of s pecificity. Low-volume tumors with a Gleason score of 6 or less may not be detected with enhanced transrectal sonography.