One of the primary criticisms of mammography is that it leads to unneeded stress and anxiety from identification and biopsy of non-cancerous findings. Contrast-enhanced mammography (CEM) has the potential to significantly reduce biopsy rates for commonly seen benign breast lesions while preserving very high cancer detection. The investigators propose a prospective clinical study of patients with diagnostic mammograms rated as BIRADS 4A or 4B and scheduled for a biopsy, in which, prior to undergoing their scheduled biopsy, a CEM procedure is performed. The investigators will test the primary hypothesis that for soft tissue lesions (i.e. masses, asymmetries, architectural distortions) initially rated BI-RADS 4A/4B adding CEM will reduce, by at least 20%, the number of biopsy recommendations for actually benign cases and, at the same time, provide a negative predictive value (NPV) higher than 95%.