Breast tumors are normally seen with mammography or ultrasound without the use of a dye but the size and extent of the tumor may be hard to see. Currently, after initial mammography, many patients undergo bilateral breast MR to further stage the local tumor. It is able to not only detect anatomic abnormalities but can also evaluate changes such as the development of new blood vessels, which occurs with the development of cancers. MRI is extremely sensitive and detects unsuspected disease in up to 25% of patients, which affects their treatment. It also detects unsuspected cancer in the other breast in some patients.

However, MRI is expensive, not always available, and some patients are unable to undergo MRI due to the presence of pacemakers, clips, or claustrophobia. Dual Energy Contrast Enhanced Digital Mammography (DE CEDM) is an investigational procedure that uses a non-standard contrast in a regular digital mammography exam that has been changed to give the needed dual energy and image. DE CEDM is not FDA approved. It is our hope that DE CEDM will also be able to detect unknown tumors because it will also detect new blood vessels. It is less expensive than MRI, could be more available to patients, and can be done on patients with pacemakers and clips. Claustrophobia will not be a problem. We plan to see if (DE CEDM) will help us better see the breast tumor and size of the breast tumor. We will also want to see if DE CEDM can detect additional unsuspected disease in the breast with the known tumor and in the other breast without a known tumor.

Inclusion Criteria:

• Women with newly diagnosed unilateral breast cancer proven through core biopsy or FNA who are planned to have (preoperative) MRI within 30 days of DE CEDM to assess extent of disease/multifocality. (All women will have bilateral digital mammography as per standard of care.) The preoperative MRI will be based on the surgeon's recommendation.
• Both breasts are present.
• Women consenting to a bilateral DE CEDM examination.

Exclusion Criteria:

• Women under 21.
• Women who have already had a lumpectomy. (Index lesion has been removed and therefore, not evaluable for the purpose of this study.)
• Women undergoing neoadjuvant chemotherapy, hormone treatment, or radiation therapy.
• Known pregnancy.
• Women who have a contraindication to the intravenous use of iodinated or gadolinium-chelated contrast agent.
• Women with breast implants.
• Women with pacemakers.
• Women with aneurysm clips that don't allow for MRI.
• Women too claustrophobic to undergo MRI.