The hyperdense MCA sign (HMCAS) refers to the appearance of the middle cerebral artery (MCA) on CT.
There is increased attenuation of the proximal portion of the MCA and it is often associated with thrombosis of the M1 MCA segment. It is one of the early signs of ischaemic stroke : MCA infarct.
The same pathological process can give an MCA dot sign when seen end on.
The sign is typically seen within 90 minutes of the ischemic event, and thus, it is very important for radiologists to recognize this sign. It can save the patient in 'golden hour' of thrombolysis (3 hours for intravenous tPA, and 6 hours for intra-arterial thrombolysis). This sign has approx. 100% sensitivity, however only 30% specificity. It is usually associated with another important sign of acute ischaemia - insular ribbon sign.
There are occasional reports of a hyperdense MCA sign seen with HSV encephalitis .
There is increased attenuation of the proximal portion of the MCA and it is often associated with thrombosis of the M1 MCA segment. It is one of the early signs of ischaemic stroke : MCA infarct.
The same pathological process can give an MCA dot sign when seen end on.
The sign is typically seen within 90 minutes of the ischemic event, and thus, it is very important for radiologists to recognize this sign. It can save the patient in 'golden hour' of thrombolysis (3 hours for intravenous tPA, and 6 hours for intra-arterial thrombolysis). This sign has approx. 100% sensitivity, however only 30% specificity. It is usually associated with another important sign of acute ischaemia - insular ribbon sign.
There are occasional reports of a hyperdense MCA sign seen with HSV encephalitis .
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