Multiparametric MRI is helpful to predict tumor focality, stage, and size in patients diagnosed with unilateral low-risk prostate cancer

To study the staging accuracy of multiparametric magnetic resonance imaging (MRI) in patients showing unilateral low-risk cancer on prostate biopsy. A total of 58 consecutive patients with low-risk cancer (D'Amico classification) and unilateral cancer involvement on prostate biopsies were included prospectively. All patients underwent multiparametric endorectal MRI before radical prostatectomy, including T2-weighted (T2W), diffusion-weighted (DW) and dynamic contrast enhanced (DCE) sequences. Each gland was divided in eight octants. Tumor foci > 0.2cm(3) identified on pathological analysis were matched with MRI findings. Pathological examination showed tumor foci > 0.2cm(3) in 50/58 glands (86%), and bilateral tumor (pathological stage >= pT2c) in 20/58 (34%). For tumor detection in the peripheral zone (PZ), T2W+DWI+DCE performed significantly better than T2W+DWI and T2W alone (P < 0.001). In the transition zone (TZ), only T2W+DWI performed better than T2W alone (P = 0.02). With optimal MR combinations, tumor size was correctly estimated in 77% of tumor foci involving more than one octant. Bilateral tumors were detected in 80% (16/20) of cases. In patients with unilateral low-risk prostate cancer on biopsy, multiparametric MRI can help to predict bilateral involvement. Multiparametric MRI may therefore have a prognostic value and help to determine optimal treatment in such patients. Prostate Cancer and Prostatic Diseases (2011) 14, 232-237; doi:10.1038/pcan.2011.9; published online 22 March 2011