THE CLINICAL VALUE OF DIFFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING FOR LOCALIZATION OF PROSTATE CANCER-COMPARISON WITH THE STEP SECTIONS OF RADICAL PROSTATECTOMY

PURPOSE The objective of our study was to compare T2-weighted magnetic resonance imaging (T2WI), combined T2-weighted and dynamic imaging (Dynamic), and combined T2-weighted and diffusion-weighted imaging (DWI) in the identification of the site of prostate cancer. MATERIALS AND METHODS Before radical prostatectomy, 85 patients with prostate cancer underwent magnetic resonance imaging using a 1.5-T endorectal coil; we excluded 3 patients treated with neoadjuvant hormonal therapy. The sites of prostate cancer in 82 patients were predicted by T2WI alone, T2WI + Dynamic, and T2WI + DWI, and the results were compared with the step-section analysis of radical prostatectomy specimens. The peripheral zone (PZ) and the transition zone (TZ) of the prostate were divided into left and right halves. Only tumors with a diameter of more than 5 mm were considered significant. RESULTS The sensitivity, specificity, positive predictive value (PPV), and the area under the receiver operating characteristic (ROC) curve (Az) for the prediction of the site of prostate cancer in the PZ of the prostate were as follows: 42%, 94%, 93%, and 0.76 for T2WI alone; 48%, 96%, 96%, and 0.78 for T2WI + Dynamic; and 50%, 96%, 96%, and 0.81 for T2WI + DWI. The sensitivity, specificity, PPV, and Az for the prediction of the site of prostate cancer in the TZ of the prostate were as follows: 31%, 92%, 76%, and 0.66 for T2WI alone; 46%, 82%, 67%, and 0.65 for T2WI + Dynamic; and 48%, 94%, 85%, and 0.71 for T2WI + DWI. CONCLUSION The Az value for the prediction of prostate cancer in the PZ and those in the TZ of the prostate was the highest for the combined T2WI and DWI approach.