1. A computer implemented method for tissue characterization based on water kinetics, the method comprising: including one or more processors for receiving DCE-MRI time course data for tissue region wherein a contrast reagent is administered prior to imaging; identifying a region of interest from the DCE-MRI data for further analysis; analyzing the data for the region of interest using computer implemented software to produce a SM Ktrans value, where the water exchange between cells or blood and interstitial spaces is assumed to be substantially infinitely fast; analyzing the data for the region of interest using computer implemented software to produce a SSM Ktrans value, where the water exchange between cells or blood and interstitial spaces is assumed to have a finite speed resulting from interaction with the contrast reagent; and determining a AKtrans value comprising SSM Ktrans-SM Ktrans.