Acute CT Brain
Acute ischaemia

Key points

  • In the context of suspected stroke, CT of the brain is performed mainly to exclude haemorrhage
  • Routinely check for subtle areas of low density
  • Check for the 'hyperdense artery' sign, and the 'insular ribbon' sign

In the setting of acute stroke the initial CT is often normal; the main purpose of performing a CT is to exclude intracranial haemorrhage.

Signs of acute stroke

Occasionally a CT brain acquired shortly after an acute vascular event will show subtle low density in the territorial area affected. Other important signs include the 'hyperdense artery' sign and the 'insular ribbon' sign. These signs are easily overlooked if not checked for routinely.

Acute territorial infarct - CT brain

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Acute territorial infarct

  • An area of low density is seen in the grey and white matter of the right frontal lobe
  • The patient presented with an acute left hemiparesis - onset 4 hours earlier

Hyperdense artery sign

In the setting of an acute infarct, CT occasionally shows thromboembolic material within a cerebral artery, most commonly the middle cerebral artery.

Dense MCA sign - CT brain

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Dense MCA sign

  • Dense thromboembolic material is seen filling the right middle cerebral artery (MCA)
  • (Same patient as image below)

Insular ribbon sign

In the context of an acute infarct, CT may demonstrate loss of clarity of the insular ribbon. This is a very subtle finding and so is easily overlooked unless checked for routinely.

Insular ribbon sign - CT brain

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Insular ribbon sign

  • The insula normally has a thin layer of cortex (see the left side)
  • In this patient (same patient as image above) there is subtle loss of clarity of this layer of cortex on the right