OBJECTIVES:To evaluate the accuracy of transrectal ultrasound-guided (TRUS) biopsy, diffusion-weighted (DW) magnetic resonance imaging (MRI), (11)C-choline (CHOL) positron emission tomography (PET), and (18)F-fluorodeoxyglucose (FDG) PET in predicting the prostatectomy Gleason risk (GR). METHODS:The study included 21 patients who underwent TRUS biopsy and multi-technique imaging before radical prostatectomy. Values from five different tests (TRUS biopsy, DW MRI, CHOL PET, FDG PET, and combined DW MRI/CHOL PET) were correlated with the prostatectomy GR using Spearman's ρ. Tests that were found to have significant correlations were used to classify patients into GR groups. RESULTS:The following tests had significant correlations with prostatectomy GR: TRUS biopsy (ρ = 0.617, P = 0.003), DW MRI (ρ = -0.601, P = 0.004), and combined DW MRI/CHOL PET (ρ = -0.623, P = 0.003). CHOL PET alone and FDG PET only had weak correlations. The correct GR classification rates were 67% with TRUS biopsy, 67% with DW MRI, and 76% with combined DW MRI/CHOL PET. CONCLUSIONS:DW MRI and combined DW MRI/CHOL PET have significant correlations and high rates of correct classification of the prostatectomy GR, the strength and accuracy of which are comparable with TRUS biopsy. KEY POINTS:• Accurate determination of the Gleason score is essential for prostate cancer management. • DW MRI ± CHOL PET correlated significantly with prostatectomy Gleason score. • These correlations are similar to that between TRUS biopsy and prostatectomy.