Value of endorectal magnetic resonance imaging at 3T for the local staging of prostate cancer.

PURPOSE To assess the accuracy of endorectal 3 T magnetic resonance imaging (MRI) in detecting extracapsular extension (ECE) and seminal vesicle invasion (SVI) of prostate cancer (PCa). MATERIALS AND METHODS 38 consecutive patients with biopsy-proven PCa underwent multiparametric endorectal MRI at 3 T prior to prostatectomy. Two readers (A with nine years of experience and B with four) used established criteria for ECE and SVI to diagnose the extent of local disease in six regions (apical, dorsolateral, basal; left and right each) with the highest chance of ECE. The standard of reference was provided by intraoperative frozen section analysis and prostatectomy specimens. RESULTS Histopathology revealed ECE in 15 of the 222 regions (10 of 37 patients) and SVI in 8 of 74 potential regions (5 of 37 patients). The sensitivity, specificity, and accuracy in detecting ECE for reader A/B were 93%/67%, 92%/95% and 92%/93% per region and 90%/80%, 74%/82% and 78%/81% per patient, respectively. The corresponding values for the detection of SVI were 80%/100%, 96%/99% and 95%/97%, respectively. CONCLUSION Endorectal 3 T MRI is a highly reliable noninvasive technique for the local staging of PCa. KEY POINTS ► Endorectal 3 T MRI provided high accuracy for the local staging of prostate cancer. ► The sensitivity in detecting extracapsular tumor growth per patient was 80% or higher. ► The specificity in detecting extracapsular extension (pT3 stage) was good.