Hyperdense MCA sign (brain)

Dr Jeremy Jones et al.

The hyperdense MCA sign refers to focal increased density of the middle cerebral artery on CT and is direct visualisation of thromboembolic material within the lumen. It is thus the earliest visible sign of MCA infarction seen immediately at the time of embolism.  It is the longitudinal equivalent of the MCA dot sign and hyperdense basilar tip sign

The hyperdensity of the arterial content is due to the thrombus having previously formed and contracted, usually within the heart or carotid bulb, prior to embolizing and occluding the MCA.

CT

The proximal portion of the MCA, often extending into the terminal supraclinoid internal carotid artery, is hyperdense compared to the other side and to the basilar tip which is often at a similar level.

Care must be taken not to over call this sign on thick axial slices only as different slice position relative to the MCA can lead to asymmetry. Review of thin-section CT and multiplanar reformats is usually able to confirm it as a true finding. 

 

Hyperdense MCA sign has been associated with poor outcome, although this is by no means established, especially in light of recent endovascular clot retrieval techniques. 

Usually, there is no differential diagnosis, as the clinical context is consistent with ipsilateral middle cerebral artery occlusion. 

Occasionally, a similar appearance may be the result of calcified atherosclerotic disease. High haematocrit can lead to elevated intravascular density, however, this is present throughout all visualised vessels. 

There are occasional reports of a hyperdense MCA sign seen with HSV encephalitis 4.

 

Stroke and intracranial haemorrhage
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Article information

rID: 5242
Section: Signs
Tags: stroke, mca
Synonyms or Alternate Spellings:
  • Dense middle cerebral artery sign
  • Hyperdense middle cerebral arterial sign
  • hyperdense middle cerebral artery sign (HMCAS)
  • Dense MCA sign
  • Hyperattenuating MCA sign

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