Brain death

Brain death refers to the irreversible end of all brain activity and is usually assessed clinically. However, as this diagnosis allows organ donation for transplantation or withdrawal of life support, most countries have specific related legal standards and practice guidelines 2.

Radiographic features

Radiology may be used when clinical tests are impossible to perform, e.g., ocular trauma precluding brainstem function assessment. Most tests rely on the absence of cerebral blood flow as a surrogate for brain death. This can be assessed by a number of modalities including nuclear medicine and catheter angiography.

CT
  • diffuse cerebral oedema with effacement of the grey-white matter borders
  • CT angiography: non-opacification of the cortical middle cerebral arteries and internal cerebral veins are the most sensitive and specific markers on CTA 3
MRI
  • T1: hypointense, with lost grey-white matter differentiation
  • T2
    • swollen gyri with hyperintense cortex
    • expected flow void may be absent in vessels
  • DWI: hemispheric high signal, severe ADC drop
Angiography (DSA)
  • no forward flow above the terminal ICA
Nuclear medicine
  • cerebral perfusion
    • flow images are obtained in the anterior projection; delayed images follow 5 to 10 minutes after the injection
    • hot nose sign: increased ECA perfusion to the nasal region (a cute sign, but of no real diagnostic value) 1
    • light bulb sign: absent intracranial uptake 
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Article Information

rID: 5240
Section: Pathology
Tag: refs
Synonyms or Alternate Spellings:
  • Cerebral death

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    Absent internal c...
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     Case 3: with hot nose sign
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    Case 8: fused images on SPECT 99mTC
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