 Our aim is to perform dynamic contrast enhanced DCE MRI on 150 patients during their routine breast MRI examination at MSKCC. This will add extra 10 min scanning time to the routine examination. High resolution submillimeter parametric maps of pathophysiologic quantities, such as tumor vessel permeability, tumor perfusion, extracellular extravascular volume fraction, will be generated from the DCE MRI data. These results will be correlated with pathology to determine new pharmacokinetic threshold so that the negative predictive value for benign lesions is close to 100. The improvement in diagnostic specificity may help to reduce unnecessary biopsies in the future. 