A comparison of endorectal magnetic resonance imaging and transrectal ultrasonography in the local staging of prostate cancer with histopathological correlation.

Objective: To assess the staging accuracy of endorectal magnetic resonance imaging (MRI), using a mid-field system, in patients with clinically localized prostate cancer and to compare the results with transrectal ultrasonography (TRUS).

Methods: Twenty patients with clinically localized prostate cancer were prospectively staged with TRUS and endorectal MRI using a 0.5 T magnet. All patients subsequently underwent radical prostatectomy and the results of pre-operative staging were compared with the histological findings.

Results: The sensitivity and specificity for diagnosing capsular penetration were 38% and 100%, respectively, for endorectal MRI, and 23% and 86% for TRUS. The sensitivity and specificity for diagnosing seminal vesicle invasion were 100% and 94%, respectively, for endorectal MRI, and 33% and 100% for TRUS. The overall staging accuracy for endorectal MRI was 75% compared with 50% for TRUS.

Conclusions: Compared with TRUS, endorectal MRI with a 0.5 T magnet provided greater sensitivity and specificity for capsular penetration and increased sensitivity for seminal vesicle invasion.