Brain death
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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 has a specific related legal standard 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 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 findings
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Diffuse cerebral edema with effacement of the grey-white matter borders,
- Reversal sign (density of cerebellum > cerebral hemispheres)
- pseudosubarachnoid appearance due to venous congestion in effaced sulci
- swollen gyri, compressed ventricles/cisterns
MRI findings
- T1 WI: hypointense, with lost grey-white matter differentiation
- T2 WI: swollen gyri with hyperintense cortex.
- DWI: hemispheric high signal, severe ADC drop
Angiography
- no forward flow above the terminal ICA
Nuclear medicine
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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
-<p><strong>Brain death</strong> 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 has a specific related legal standard and practice guidelines <sup>2</sup>.</p><h4>Radiographic features</h4><p>Radiology may be used when clinical tests are impossible to perform, e.g <a href="/articles/ocular-trauma">ocular trauma</a> precluding <a href="/articles/brainstem">brainstem</a> function assessment. Most tests rely on absence of <a href="/articles/cerebral-blood-flow">cerebral blood flow</a> as a surrogate for brain death. This can be assessed by a number of modalities including nuclear medicine and catheter angiography.</p><h5>Angiography</h5><ul><li>no forward flow above the terminal <a href="/articles/ica">ICA</a>- +<p><strong>Brain death</strong> 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 has a specific related legal standard and practice guidelines <sup>2</sup>.</p><h4>Radiographic features</h4><p>Radiology may be used when clinical tests are impossible to perform, e.g <a href="/articles/ocular-trauma">ocular trauma</a> precluding <a href="/articles/brainstem">brainstem</a> function assessment. Most tests rely on absence of <a href="/articles/cerebral-blood-flow">cerebral blood flow</a> as a surrogate for brain death. This can be assessed by a number of modalities including nuclear medicine and catheter angiography.</p><h5>CT findings</h5><ul><li>Diffuse cerebral edema with effacement of the grey-white matter borders,<ul>
- +<li>Reversal sign (density of cerebellum > cerebral hemispheres)</li>
- +<li>pseudosubarachnoid appearance due to venous congestion in effaced sulci</li>
- +<li>swollen gyri, compressed ventricles/cisterns</li>
- +</ul>
- +</li></ul><h5>MRI findings</h5><ul>
- +<li>T1 WI: hypointense, with lost grey-white matter differentiation</li>
- +<li>T2 WI: swollen gyri with hyperintense cortex.</li>
- +<li>DWI: hemispheric high signal, severe ADC drop</li>
- +</ul><h5>Angiography</h5><ul><li>no forward flow above the terminal <a href="/articles/ica">ICA</a>
- +<li>light bulb sign: absent intracranial uptake </li>
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