Prostate tumor DCE-MRI data sets from 11 patients were shared among nine institutions, which determined AIFs using site-specific methods. The managing center performed pharmacokinetic data analysis using the Shutter-Speed model and these AIFs, and their scaled variants obtained with the reference-tissue method. Among the estimated parameters, Ktrans has the highest whereas τi has the lowest variability due to AIF uncertainty. The use of reference-tissue-adjusted AIFs reduces parameter variations. kep and τi are nearly insensitive to AIF scaling, suggesting that they may be robust imaging biomarkers in multicenter DCE-MRI trials where accurate and consistent AIF determination may be unattainable across sites.