Mapping Draining Lymph Nodes in CNS Malignancies

The purpose of this research study is to determine whether the lymph nodes that drain a brain tumor can be detected by imaging after injection of a substance called Tc-99m tilmanocept directly into the brain tissue around the tumor. Tc-99m tilmanocept is a radioactive substance that is used to find lymph nodes by injecting it and then scanning the body with a device that can trace its radioactivity. In this study, the investigators are looking to see how long it takes the Tc-99m tilmanocept to travel from the tumor to the lymph nodes. The investigators will be using it to map lymph nodes as they relate to specific brain areas.