The three essential findings in brain death are coma, absence of brainstem reflexes, and apnea. Legal requirements for its diagnosis vary by country. 

Primarily the diagnosis is clinical but images of the brain can be used to assess signs that indicate the absence of cerebral circulation. 

Non-contrast-enhanced CT of the head is useful for assessing the severity of brain injury in the suspicion of brain death.

The diagnosis of this case was made by clinical findings and intracerebral arteriography. The non-contrast CT was made for evaluating possible reversible causes of coma and showed signs of extensive anoxic encephalopathy.