TABLE 2.

Diagnostic Imaging Used to Confirm Brain Death (1,2,7)

TestDiagnostic criterionAdvantageDisadvantage
Four-vessel conventional cerebral angiographyAbsence of blood flow at or beyond carotid bifurcation or circle of WillisTraditional gold standard among cerebral blood flow testsRequirement for transportation to imaging department
Invasive
Contrast precautions for kidneys
Contrast stasis or delayed filling in intracranial arteries
Radionuclide perfusion scintigraphyAbsence of blood flow at or beyond carotid bifurcation or circle of WillisSensitive for confirming brain death in presence of confounding variablesRequirement for transportation to imaging department
Hollow skull if using brain-specific radiopharmaceuticalPotential for limitation of brain stem evaluation via planar imaging
Requirement for coordination with multiple hospital personnel and nuclear pharmacy
Possibility that on-call nuclear medicine staffing is not supported
Restricted off-hours availability of radiopharmaceuticals
Transcranial DopplerPresence of small systolic peaks without diastolic flow or reverberating flow pattern, indicating high vascular resistance and supporting diagnosis of brain deathNoninvasiveRequirement for technical experience
Can be done at bedsideEvaluation precluded by 10%–25% prevalence of temporal bone thickening
No contrast medium usedReports of both false-positive and false-negative results (compared with cerebral angiography or other standard)
MRI of arterial blood flowAbsence of arterial blood flowDemonstration of variable degrees of cerebral edema and mass effectRequirement for transportation to imaging department
Requirement for gadolinium contrast agent for improved sensitivity
Requirement for patients to lie flat
Possibility of short periods in which clinical monitoring is impossible
CT angiographyAbsence of cerebral circulation perfusionWidespread availabilityUncertain clinical utility of CT angiography
Requirement for iodine contrast injection