Radionuclide studies in the determination of brain death: criteria, concepts, and controversies.

Forty years after the publication of a landmark paper by the Ad Hoc Committee of the Harvard Medical School, the general concept of brain death has achieved widespread acceptance. In the United States, irreversible dysfunction of the brain and brainstem are required for the diagnosis of brain death. Although primarily based on clinical evaluation, confirmatory examinations, including radionuclide blood flow studies, play an important role in augmenting the physical examination in special situations when some of its specific components cannot be performed or reliably evaluated.