The purpose of this study is to determine whether a supine breast MRI obtained with a second intravenous injection of gadolinium contrast immediately after a standard clinical prone breast MRI will provide sufficient tumor visualization to allow a Radiologist to define and outline the tumor edges ("segment" the tumor). Accurate segmentation will allow a 3-D image of the tumor to be generated to create a breast cancer locator (BCL) surgical device to in aid removal of breast cancers.

The clinical pre-operative breast MRI exam will be obtained in the prone position with intravenous (IV) Gadolinium (Gd) contrast injection per standard of care clinical protocol. After completion of the standard clinical prone breast MRI, the participant will be re-positioned and the investigative supine breast MRI protocol with a second dose of IV Gd will be obtained. A second dose of contrast equal to the first dose will be given, and additional images will be obtained in the supine position. Subtraction images will be generated for both the prone and the supine sequences. It is hypothesized that the second contrast injection will generate tumor-to-fibroglandular contrast differences such that supine subtraction images will allow visualization and segmentation of the tumor equal to prone segmentation images. It is expected that the addition of a second injection of contrast will improve the ability to visualize and accurately segment the supine post-Gd images. While the total dose of gadolinium delivered in two injections is twice the amount normally given during a clinical prone breast MRI, this total dose is equal to that administered for other clinical MRI studies such as cardiac MRI.

No additional imaging or testing will be required for this research study following the standard clinical MRI.

Inclusion Criteria:

1. Age > 18 years.
2. Female gender.
3. Histologic diagnosis of invasive breast cancer or ductal carcinoma in situ.
4. Tumor size at least 1 cm in diameter as visualized on mammogram or US.
5. A staging, pre-operative breast MRI is considered to be clinically indicated.
6. Ability to voluntarily provide informed consent to participate prior to any study-related assessments/procedures being conducted.

Exclusion Criteria:

1. Absolute contraindication to MRI, including presence of implanted electrical device. (pacemaker or neurostimulator incompatible with MRI), aneurysm clip, or metallic foreign body in or near eyes.
2. Severe claustrophobia.
3. Contraindication to the use of gadolinium-based intravenous contrast, including anaphylaxis. Any known history of nephrogenic systemic fibrosis (NSF).
4. History of median sternotomy.
5. Pregnancy. All women of child-bearing age will be questioned about possible pregnancy status. In women who are unsure of pregnancy status, a urine pregnancy test will be performed.
6. Patients who have received neoadjuvant chemotherapy for their current diagnosis.
7. Known compromised renal function including chronic, severe kidney disease (GFR < 30 ml/min/1.73m2), or acute kidney injury.

Female