Comparative Performance of Molecular Breast Imaging (MBI) to Magnetic Resonance Imaging (MRI) of the Breast in Identifying and Excluding Breast Carcinoma in Women at High Risk for Breast Cancer

Primary Objective: -To compare the diagnostic performance of Molecular Breast Imaging (MBI) to breast Magnetic Resonance Imaging (MRI) in women who are at high risk of developing breast cancer. Secondary Objectives: * To evaluate the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MBI compared to breast MRI in women who are at high risk of developing breast cancer. * To assess patient preference for the two examinations by conducting a post examination survey and follow up questionnaire (see addendum). * To assess the relationship of tumor size, histologic subtype and location of lesion with lesion conspicuity (mild, moderate, marked uptake compared to background activity) according to MBI lexicon \[1\].