Absence of Flow Voids.

• Diagnosis: Brain death.
• Discussion:

1-Accurate diagnosis of brain death is necessary prior to discontinuing life support in a comatose patient.
2-Clinical examination is only reliable in the absence of hypothermia; barbiturates; sedatives and hypnotics.
3-If the diagnosis is unclear; imaging examination such as nuclear medicine; CT; MRI or angiography may be helpful.

• Imaging signs:

A)On contrast enhanced MR Imaging -----> Absence of intra cranial perfusion above he level of skull base.
B) On T2 imaging -----> Absence of flow void signs inside arterial cranial vessels.
C) Additional imaging signs:
-Diffuse cerebral edema with obscuration of grey white matter diferentiation.
- Downward transtentorial and tonsillar herniation.
- MR Hot Nose Sign: Nasal and scalp enhancement due to increased collateral flow to external carotid artery.

Absence of intra cranial perfusion above he level of skull base.

Absence of flow void signs inside arterial cranial vessels.

Hot Nose Sign