Contrast-enhanced ultrasonography of the prostate: various imaging findings that indicate prostate cancer

Objectives: • To perform transrectal ultrasonography (TRUS) with an ultrasonography (US) contrast agent to visualize prostate cancer. • To explore the possibility of targeted biopsy by studying the findings obtained by different cancerous tissue imaging modalities and evaluating needle biopsies from prostate cancer using contrast-enhanced ultrasonography (CEUS).

Patients and methods: • In all, 41 patients undergoing prostate biopsy and 13 patients undergoing prostatectomy received i.v. injection of the US contrast agent (Sonazoid®). • We evaluated pre-contrast and contrast-enhanced US images, and then compared ultrasonographic images and the pathological findings.

Results: • Cancer was significantly more frequent at the sites of targeted biopsy where CEUS findings suggested cancer (36.3%) than at sites of systematic biopsy (17.7%, odds ratio = 2.7, P =0.0026). • In cases with prostate-specific antigen (PSA) level < 10 ng/mL, in particular, prostate cancer was detected at a significantly higher rate by targeted biopsy than by systematic biopsy (27.3 vs 9.5%, odds ratio = 3.4, P = 0.013). • Pathological examination found 26 tumours in prostatectomy specimens. The diameters of the 10 CEUS-identified tumours were significantly greater than those of the 16 lesions missed by US (mean 18.7 vs 5.9 mm). • CEUS findings suggestive of cancer varied widely: strong contrast enhancement, rapid contrast enhancement, vessels with abnormal perfusion and low contrast enhancement.

Conclusions: • CEUS could be useful for targeted biopsy in patients with a PSA level < 10 ng/mL. • The CEUS findings suggestive of prostate cancer are more varied than previously reported. • Detailed examination of CEUS images and application of the data to prostate biopsy could lead to more efficient diagnosis.