Ancillary Imaging Tests for Confirmation of Brain Death

Brain death is an irreversible termination of functions of the entire brain including brain stem. The American Association of Neurology has defined brain death with three cardinal criteria, namely cessation of the functions of brain including brain stem, coma or unresponsiveness, and apnea. Ancillary testing is done in situations where clinical criteria of brain death cannot be determined by neurological examination or by apnea test. Ancillary tests for determining brain death can be primarily divided into two groups. One group includes tests that can test brain’s electrical functions and the other group includes tests that can document cerebral blood flow in the brain on imaging. In this chapter, we present characteristics of the ideal ancillary test in the diagnosis of brain death and also describe various types of ancillary imaging tests used in the clinical setting for brain death determination and the merits and demerits associated with these techniques