Purpose： The aim of this study was to determine whether PET （positron emission tomography） imaging parameters from simultaneous ^11C-choline PET/MRI （magnetic resonance imaging） could be used to characterize primary prostate cancer. Methods： Forty-six patients with biopsy-proven high-risk prostate cancer （clinical T stage ≥ cT2c, a Gleason score 〉 8, or PSA （prostate-specific antigen） level 〉 20 ng/mL） were prospectively enrolled. A SUV （standardized uptake value） histogram analysis including maximum SUV, mean SUV, SUV variance, SUV entropy, MTV （metabolic tumor volume）, and UVP （uptake volume product） was applied for the calculation of PET imaging parameters. Correlations between the PSA level and Gleason score were then evaluated. Results： Maximum SUV, mean SUV, MTV, UVP, and SUV variance were significantly correlated with PSA level, whereas SUV variance was the only parameter negatively correlated with the Gleason score. Multivariate logistic regression analysis demonstrated that MTV and PSA level at diagnosis were independent predictors of positive distant metastasis status. Conclusions： PET imaging parameters from simultaneous ^11C-choline PET/MRI were correlated with PSA level. However, ^11C-choline metabolic tumor heterogeneity was not associated with biospecimen-derived Gleason scores in prostate cancer. To apply PET texture quantification analysis to prostate cancer, a more specific PET radiotracer is required.