Diagnostic Imaging Used to Confirm Brain Death (1,2,7)
Test | Diagnostic criterion | Advantage | Disadvantage |
---|---|---|---|
Four-vessel conventional cerebral angiography | Absence of blood flow at or beyond carotid bifurcation or circle of Willis | Traditional gold standard among cerebral blood flow tests | Requirement for transportation to imaging department |
Invasive | |||
Contrast precautions for kidneys | |||
Contrast stasis or delayed filling in intracranial arteries | |||
Radionuclide perfusion scintigraphy | Absence of blood flow at or beyond carotid bifurcation or circle of Willis | Sensitive for confirming brain death in presence of confounding variables | Requirement for transportation to imaging department |
Hollow skull if using brain-specific radiopharmaceutical | Potential 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 Doppler | Presence of small systolic peaks without diastolic flow or reverberating flow pattern, indicating high vascular resistance and supporting diagnosis of brain death | Noninvasive | Requirement for technical experience |
Can be done at bedside | Evaluation precluded by 10%–25% prevalence of temporal bone thickening | ||
No contrast medium used | Reports of both false-positive and false-negative results (compared with cerebral angiography or other standard) | ||
MRI of arterial blood flow | Absence of arterial blood flow | Demonstration of variable degrees of cerebral edema and mass effect | Requirement 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 angiography | Absence of cerebral circulation perfusion | Widespread availability | Uncertain clinical utility of CT angiography |
Requirement for iodine contrast injection |