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IMAGE INTERPRETATION · BRAIN IMAGING

Brain Death Scan: Absent Cerebral Perfusion

Brain scan statics at 5, 10, and 20 minutes showing absence of cerebral perfusion — only scalp/skull activity visible
Brain scan statics at 5, 10, and 20 minutes showing absence of cerebral perfusion — only scalp/skull activity visible

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Question

A brain death radionuclide cerebral blood flow study is performed in a comatose patient on a ventilator. The study shows complete absence of cerebral perfusion (no activity in the cerebral hemispheres or cerebellum) with visualization only of scalp and skull activity ('hollow skull sign'). This finding is diagnostic of:

  1. ASevere head injury with residual perfusion
  2. BLocked-in syndrome
  3. CPersistent vegetative state
  4. DBrain death — no cerebral blood flow confirming cessation of all brain function
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D. Brain death — no cerebral blood flow confirming cessation of all brain function

Radionuclide cerebral blood flow imaging (using Tc-99m HMPAO or Tc-99m DTPA) can confirm brain death by demonstrating complete absence of cerebral perfusion. In brain death, the markedly elevated intracranial pressure (equal to or exceeding systemic perfusion pressure) prevents blood from entering the cerebral circulation. The study shows: (1) absent intracranial activity; (2) preserved scalp and skull blood flow ('hollow skull' or 'empty light bulb' sign); (3) absent posterior fossa/cerebellar perfusion. This nuclear medicine finding is one of several ancillary confirmatory tests for brain death when clinical assessment alone is insufficient (e.g., pharmacologic sedation, metabolic disturbances).

More brain imaging images

Brain perfusion SPECT — comparison of ictal and interictal statesIctal SPECT: Hyperperfusion at the Seizure Focus I-123 DaTSCAN SPECT (transverse slices) showing asymmetrically reduced striatal dopamine transporter uptakeDementia with Lewy Bodies on DaTscan Brain FDG-PET — hypometabolism pattern in Alzheimer's diseaseAlzheimer’s Disease on FDG PET Brain perfusion SPECT, transverse slices showing focal perfusion defectFocal Perfusion Defect on Brain SPECT Brain perfusion SPECT, transverse slices showing focal perfusion defectBrain Perfusion SPECT: Injection Environment Brain perfusion SPECT (Tc-99m ECD), transverse slices — normal studyNormal Tc-99m ECD Brain SPECT: Gray vs White Matter
← Frontotemporal Dementia on Brain Perfusion SPECTIctal SPECT: Hyperperfusion at the Seizure Focus →

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