Discrimination of prostate cancer from normal peripheral zone and central gland tissue by using dynamic contrast-enhanced MR imaging

PURPOSE To evaluate which parameters of dynamic magnetic resonance (MR) imaging and T2 relaxation rate would result in optimal discrimination of prostatic carcinoma from normal peripheral zone (PZ) and central gland (CG) tissues and to correlate these parameters with tumor stage, Gleason score, patient age, and tumor markers. MATERIALS AND METHODS Of 58 patients with prostatic carcinoma, 36 were included for analysis. Patients underwent MR imaging at 1.5 T with an endorectal-pelvic phased-array coil and subsequently underwent prostatectomy. A T2-weighted turbo spin-echo sequence, an intermediate-weighted sequence, and a fast T1-weighted gradient-echo sequence (seven sections in 2.03 seconds) during bolus injection of 0.1 mmol gadopentetate dimeglumine per kilogram of body weight were performed. Contrast agent concentration-time curves were obtained for prostatic carcinoma and normal PZ and CG tissue by using whole-mount sections to guide placement of regions of interest. Onset time, time to peak, peak enhancement, relative peak enhancement, washout, and T2 relaxation rates were calculated. Multivariate receiver operating characteristic analysis was performed with and without relative peak enhancement. RESULTS Results of multivariate receiver operating characteristic analysis showed that relative peak enhancement demonstrated the highest area under the receiver operating characteristic curve (AUC) in the PZ and the CG (AUC = 0.93, 0.82). Results of multivariate analysis without relative peak enhancement showed that relative peak enhancement in the PZ and washout in the CG demonstrated the highest AUC (AUC = 0.9, 0.81). Pearson correlation coefficients between the dynamic parameters or T2 relaxation rates in carcinoma and the tumor stage, Gleason score, patient age, and tumor markers ranged between 0.02 and 0.44. CONCLUSION The optimal parameter for discrimination of prostatic carcinoma in the PZ and CG was relative peak enhancement. If relative peak enhancement was not used, then peak enhancement was optimal in the PZ, and washout was optimal in the CG. Poor-to-moderate correlation was present between the dynamic parameters or T2 relaxation rate in carcinoma and the tumor stage, Gleason score, patient age, tumor volume, and prostate-specific antigen.