Radiological approach to brain death.

Brain death is a complex clinical diagnosis with significant medical and legal implications that sometimes requires the use of ancillary tests to confirm the absence of electrical activity or cerebral blood flow (CBF). Among the ancillary tests used to assess CBF are: transcranial Doppler ultrasound, digital subtraction cerebral angiography, CT angiography (CTA), MR angiography, and scintigraphy. This article reviews these techniques, with particular emphasis on CTA, its multiphase protocol, the imaging findings that support the diagnosis of brain death, recommendations for radiology report writing, and potential pitfalls in interpretation. We also review specific considerations for paediatric patients and the discrepancies between international societies on the use of ancillary tests both in adults and children.