Outline the indications, advantages and disadvantages of cerebral perfusion scanning for the certification of brain death.
1. Any doubt about the primary diagnosis of the cause of coma.
2. Possible drug or metabolic cause of coma.
3. Cranial nerves can not be tested adequately e.g. periorbital oedema, eye injuries, ruptured tympanum
4. Apnoea test can not be performed e.g. cervical cord injury, cardiorespiratory instability.
5. confirmation of brain death in some countries (not ANZ)
• Highly specific
• Does not require preconditions as for clinical testing –ie patient can be cold, hypoxic, sedated, undiagnosed, etc
• Can be done at the bedside – if portable gamma camera
• Safe – non-toxic marker (Te99m HMPAO) can be delivered via peripheral vein
• Quick – answer can be given within 30 minutes
• Provides a hard copy – clear permanent documentation of brain death
• Requires specialized equipment, marker and staff (nuclear medicine specialist) usually only available in major centres
• Requires patient transport – if no portable camera
• Can show minimal flow ( e.g. from meningeal vessels), cannot easily be repeated, and not very soon after first test
This question refers specifically to the Tc-99 HMPAO SPECT scan, which (after the four-vessel DSA) is viewed by the ANZICS Statement on Death and Organ Donation as the second best way of confirming that there is no blood flow to the noggin.
The indications for imaging to confirm brain death, broadly, are as follows:
The indications for choosing a radionuclide scan, rather than a DSA, may be as follows:
Advantages of the HMPAO-SPECT:
Disadvantages of HMPAO-SPECT:
Wieler, H., et al. "Tc-99m HMPAO Cerebral Scintigraphy A Reliable, Noninvaslve Method for Determination of Brain Death." Clinical nuclear medicine18.2 (1993): 104-109.
Donohoe, Kevin J., et al. "SNM practice guideline for brain death scintigraphy 2.0." Journal of nuclear medicine technology 40.3 (2012): 198-203.
Munari, Marina, et al. "Confirmatory tests in the diagnosis of brain death: comparison between SPECT and contrast angiography." Critical care medicine33.9 (2005): 2068-2073.
Joffe, Ari R., Laurance Lequier, and Dominic Cave. "Specificity of radionuclide brain blood flow testing in brain death: case report and review." Journal of intensive care medicine 25.1 (2010): 53-64.
Heran, Manraj KS, Navraj S. Heran, and Sam D. Shemie. "A review of ancillary tests in evaluating brain death." The Canadian Journal of Neurological Sciences35.4 (2008): 409-419.