Inclusion Criteria:

- Histologically confirmed malignancy with the presence of intraparenchymal brain
metastases.

- A diagnostic contrast enhanced MRI demonstrating the presence of brain metastases
performed within two weeks prior to registration.

- Age ≥ 18 years.

- Must be scheduled or planning to be scheduled for SRS treatment.

- Karnofsky performance status ≥60.

- Patient must sign a study-specific informed consent form. If the patient's mental
status precludes his/her giving informed consent, written informed consent may be
given by the patient's legal representative.

Exclusion Criteria:

- Unable to provide informed consent

- Major medical illness including poor cardiac or pulmonary status which would result
in inability of the patient to lie down for the procedure.

- Inability to obtain histologic proof of malignancy.

- Younger than 18 years of age.

- Serum creatinine > 1.3 mg/dl.

- Karnofsky performance status of ≤50.

- Allergy to either CT or MR contrast dyes.