Contrast-enhanced ultrasonography of the prostate with Sonazoid.

Objective: The diagnosis of prostate cancer is based on the results of ultrasonography-guided needle biopsy of the prostate, but cancer foci are often not visible in conventional transrectal ultrasonography. Sonazoid is a new microbubble contrast agent. The purpose of our study was to compare areas of contrast material enhancement in the prostate at ultrasonography with whole-mount radical prostatectomy specimens to determine if the use of Sonazoid improves the detection rate of prostate cancer.

Methods: Fifty patients with biopsy-proven cancer of the prostate who were scheduled to undergo radical prostatectomy were recruited for this study. The day before the operation, each patient was evaluated with ultrasonography at baseline and again during intravenous infusion of Sonazoid. A map of ultrasonography findings was created prospectively at the time of imaging. Following radical prostatectomy, independent mapping of the pathologic results was performed and the maps were compared.

Results: Ultrasonography evaluation at baseline demonstrated that at least one focus of cancer was identified in 20 of the 50 subjects (40.0%). Meanwhile at least one cancer focus was enhanced in 31 of the 50 patients (62.0%) when Sonazoid was used. The combination of baseline grayscale imaging and contrast-enhanced imaging allowed identification of at least one focus of cancer in 40 patients (80.0%). Contrast-enhanced ultrasonography can improve sensitivity, especially for the detection of large cancer, peripheral zone cancer and highly malignant cancer.

Conclusions: Our study has demonstrated significantly improved detection of prostate cancer with the combination of baseline grayscale imaging and contrast-enhanced imaging compared with conventional ultrasonography techniques only, and this technique may be applicable to targeted biopsy.