Scientists have taken advantage of the powerful imaging capability of computed tomographic and magnetic resonance (MR) scanners to analyze brain tumor morphology in vivo. Recently, the development of functional MR imaging techniques have added the ability to noninvasively examine brain tumor function and physiology with near real-time temporal resolution, and spatial resolution approaching that of anatomic images. This advance allows the study of cerebral blood volume, cerebral blood flow, and stimulated cortical activity, which have traditionally been within the domain of positron emission tomography (PET) research. PET research on brain tumors continues mainly with research into glycolytic rates and comparison with proton MR spectroscopic lactate data. These comparisons are facilitated by the refinement of two-dimensional MR spectroscopic techniques, which provide comparable spatial resolution to that of PET. On a more clinical note, several prospective studies involving the MR contrast agent gadolinium have been carried out, specifically those optimizing the timing of contrast-enhanced postoperative MR scans after resection of glioblastomas, using triple-dose contrast to increase sensitivity to brain metastases, and using contrast-enhanced MR imaging to study the efficacy of embolization in meningiomas.