 Our aim is to perform MR Spectroscopy MRS on 150 patients at the end of their clinically indicated routine breast MRI guided biopsy and breast MRI guided needle localization examination using a software package from General Electric Medical Systems Milwaukee,WI. This will add time to the routine examination but will not involve additional injections of contrast. We will analyze the spectroscopic data to determine if benign lesions can be reliably differentiated from malignant ones. The MR Spectroscopy MRS will be administered at Memorial Sloan Kettering Cancer Center, 1275 York Ave, NY,NY 10021. 