Isotope scanning using technetium 99m pertechnetate has fallen into disue since the advent of x-ray computerized tomography. Regional brain blood flow studies have been demonstrated and is of use in localizing such foci. Cisternography as a predictive tool in normal pressure hydrocephalus is fallin into disue. Positron tomographic scanning is a potent research tool that can demonstrate both regional glycolysis and blood flow. Unfortunately, it is extremely expensive and complex to apply in a clinical setting. With support from the National Institutes of Health, seven extramural centers have been funded to develop positron tomographic capabilities, and they will greatly advance our knowledge of stroke pathophysiology, seizure disorders brain tumors and various degenerative diseases. Nuclear magnetic resonance imaging is a potentially valuable tool since it creates tomographic images representing the distribution of brain water. No tissue ionization is produced, and images comparable to second-generation computerized tomographic scans are already being produced in humans.