Assessing Dynamic Magnetic Resonance (MR) Imaging in Patients With Recurrent High Grade Glioma Receiving Chemotherapy

The purpose of this study is to learn more about imaging changes induced by a new therapeutic agent, bevacizumab with the standard steroid, dexamethasone in patients with high grade glioma. Magnetic resonance imaging (MRI) will be used to evaluate the difference between the 2 treatments. The usual contrast agent (gadolinium) and an iron containing contrast agent called "ferumoxytol" may help us to evaluate the differences between bevacizumab and dexamethasone effects on imaging of a brain tumor called high grade glioma. For this purpose, after intravenous contrast agent injection, special MR scans (called: dynamic perfusion, blood-brain barrier (BBB) permeability measurement) will be performed to see the microvascular changes in the brain and tumor.