Inclusion Criteria:  The exam including T1WI、T2WI and multiple b-value DWI. Comfired by pathology as prostate cancer or benign prostatic hyperplasia in one month after the MRI exam.  Exclusion Criteria:  1.No Gleason score data. 2.Awful quality of imagings or artifacts affectting diagnosis. 3.No lesion larger than 0.5cm. 4.Any surgery or treatment before MRI exam. 5.Biopsy in 4 weeks before MRI exam.