This study will examine a non-invasive method to assess vasculature, that is, the development of a blood supply necessary to the growth of tumors. The hope is to identify the way that genes are expressed within the tumor itself, from areas shown as low flow versus those shown as high flow on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

Most patients with solid epithelial cancers, those that develop on free surfaces or linings inside the body, die because of the distant spread of tumors-metastasis. After that spread, a cure is more difficult than if the tumors were detected early or locally. Tumors develop a new supply of blood.

Traditional anticancer therapies have had the goal of causing a decline in the tumor. Yet by focusing on the tumor's blood supply, microscopic differences between tumors and clonal differences within tumors may be avoided. Doing so may overcome tumor resistance to treatment and may result in treatments that can be more universally applied across tumor types.

Female patients 18 years of age enrolled in the protocol Analysis of Brain Metastasis in Patients with Breast Cancer, with and without Over-Expression of HER-2, who will undergo an MRI scan immediately before surgery will be invited to participate in this study. Patients seen in the oncology outpatient clinic of the NIH Clinical Center or by referral from outside physicians may be eligible for this study.

Participants will undergo DCE-MRI immediately before the craniotomy-the surgery scheduled-in conjunction with other clinically indicated MRI. The preoperative MRI will take about 30 minutes, and the DCE-MRI will take no more than 15 minutes. During the MRI, patients will lie still on a table that can slide in and out of a metal cylinder surrounded by a strong magnetic field. They may be asked to lie still for up to 5 minutes at a time. As the scanner takes pictures, there will be loud knocking noises, and the patients will wear earplugs to muffle the sound. Patients will be able to communicate with the MRI staff at all times during the scan and may ask to be moved out of the machine at any time. During part of the MRI, patients will receive a contrast agent, one that is gadolinium-based, into a vein. This agent changes the relative brightness or contrast on the MRI image under some conditions. Before that agent is used, patients will be asked about any previous allergic reactions to gadolinium-based contrast agents.