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.