MCA dot sign (brain)

The middle cerebral artery MCA) dot sign, also known as the Sylvian fissure sign, is seen on CT of the head and represents the cross-sectional M2 equivalent of the hyperdense MCA sign. Rather than imaging a length of middle cerebral artery (typically the M1 segment), the dot sign represents a thromboembolus within a segmental branch of the MCA located within the Sylvian fissure (M2 segment). The sign appears when the high-attenuation MCA is viewed in axial section, since the occluded vessel courses in a plane perpendicular to the transverse plane of imaging.

Pathology

The MCA dot sign is an early marker of thromboembolic occlusion of the distal MCA branches seen in the Sylvian fissure (M2 segment). The principally affected area of the brain is the insula.

Sensitivity and specificity

This sensitivity of this CT sign is approximately 35%, while its specificity may be as high as 100% 3.

Treatment and prognosis

The MCA dot sign is prognostic of poor outcome in patients with ischaemic stroke, but with a better outcome than the hyperdense MCA sign 2.

As such, single studies have assessed the possibility of automated detection 4 and its value in prediction of secondary symptomatic intracranial haemorrhage 5.

Punctate vascular calcification along the M2 segment of the MCA within the Sylvian fissure represent a potential mimic of this sign.

Stroke and intracranial haemorrhage
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Article information

rID: 11092
Section: Signs
Synonyms or Alternate Spellings:
  • Middle cerebral artery dot sign
  • Middle cerebral artery (MCA) dot sign
  • Middle cerebral arterial dot sign

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