PurposeTo investigate the value of multiparametric magnetic resonance imaging (mpMRI) for extracapsular extension (ECE) in prostate cancer (PCa).Materials and MethodsIn all, 292 patients who received radical prostatectomy and underwent preoperative mpMRI at 3T were enrolled retrospectively. For determining the associations with ECE, the likelihood of ECE was assessed qualitatively on T2‐weighted imaging (T2WI) and combined T2WI and diffusion‐weighted imaging (DWI) or dynamic contrast‐enhanced imaging (DCEI). Quantitative MRI parameters were measured in PCa based on histopathological findings. Two models for detecting ECE including imaging and clinical parameters were developed using multivariate analysis: Model 1 excluding combined T2WI and DWI and DCEI and Model 2 excluding combined T2WI and DWI, and combined T2WI and DCEI. Diagnostic performance of imaging parameters and models was evaluated using the area under the receiver operating characteristics curve (Az).ResultsFor detecting ECE, the specificity, accuracy, and Az of combined T2WI and DWI or DCEI were statistically better than those of T2WI (P < 0.05), and all quantitative MRI parameters showed a statistical difference between the patients with and without ECE (P < 0.05). On multivariate analysis, significant independent markers in Model 1 were combined T2WI and DWI, combined T2WI and DCEI, and Ktrans (P < 0.05). In Model 2, significant markers were combined T2WI and DWI and DCEI, Ktrans, Kep, and Ve (P < 0.05). The Az values of models 1 and 2 were 0.944 and 0.957, respectively.ConclusionmpMRI may be useful to improve diagnostic accuracy of the models for determining the associations with ECE in PCa.Level of Evidence: 4Technical Efficacy: Stage 2J. MAGN. RESON. IMAGING 2017;45:1760–1770