The Role of Radionuclide Imaging in Brain Death Diagnosis

Brain death is defined as the complete and irreversible cessation of the entire brain function, including the brainstem. For the most part, the diagnosis is clinical, and ancillary testing is only needed when clinical criteria are not satisfied. Differences exist in brain death diagnosis policy in the confirmation of brain death with ancillary testing and the particular test used. Demonstration of the absence of cerebral circulation is a reliable indicator of brain death. Currently, there are no agreed-on universal criteria for ancillary imaging investigation. However, several guidelines and meta-analyses have referred to radionuclide imaging as the most reliable, accurate, and validated ancillary imaging procedure in the confirmation of brain death. Whenever available, lipophilic agents should be preferred using tomographic imaging in all or as needed. False results may occur because of slight temporal delays in flow-function interaction, and such findings may carry prognostic information. Detectable cerebral circulation in the clinical presence of brain death most probably indicates that the process of dying is not yet complete. The results of radionuclide studies may also suggest that the loss of viability in a significant proportion of brain tissue is not compatible with life.