Brain Death: Diagnosis and Imaging Techniques.

Area of Science:

• Neurology
• Radiology
• Medical Diagnostics

Background:

• Brain death (BD) is the irreversible cessation of all entire brain functions, including the brainstem.
• Diagnosis is primarily clinical, based on neurologic examination, including coma, absence of brainstem reflexes, and apnea.

Purpose of the Study:

• To outline the diagnostic criteria and ancillary tests for brain death.
• To highlight the role of radiologists in diagnosing brain death and interpreting imaging findings.

Main Methods:

• Review of American Academy of Neurology (AAN) guidelines for brain death diagnosis.
• Discussion of ancillary tests: electroencephalogram, cerebral angiography, transcranial Doppler, and nuclear scintigraphy.
• Exploration of advanced imaging techniques like CTA, CT/MR perfusion, and their potential role.

Main Results:

• AAN criteria emphasize coma, absent brainstem reflexes, and apnea.
• Digital subtraction angiography is the gold standard for confirming absent cerebral blood flow.
• Advanced imaging (CTA, CT/MR perfusion) shows promise but is not currently AAN-recommended.
• Transcranial Doppler reveals specific flow patterns indicative of cerebral circulatory arrest.
• Radiologists can identify hypoxic/ischemic damage and rule out mimics of brain death.

Conclusions:

• Ancillary tests are crucial when clinical examination is inconclusive.
• Radiologists are vital in detecting irreversible brain damage and supporting brain death diagnosis.
• Awareness of imaging limitations and pitfalls is essential for accurate diagnosis.