The purpose of this study is to determine the safety of directly injecting a chemotherapy drug called Topotecan and a contrast agent called Gadolinium into malignant brain tumors. Currently there is no effective treatment for recurrent malignant brain tumors, which means the brain tumor has returned after the original tumor has been treated. Most systemic chemotherapy drugs have toxic side effects, which make them difficult to use for brain tumors. However, we are doing this study to find out if using an experimental method of directly infusing the drug into the tumor, allows research...