The hyperdense MCA sign (HMCAS) refers to the appearance of the middle cerebral artery (MCA) on CT. It has been associated with poor outcome, although this is by no means established.5
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 4.
False-positives : (asymptomatic patients - usually bilateral)
- high haematocrit
- calcified atherosclerotic disease5
This article is in need of some more references!
You can make a difference to Radiopaedia.org by adding some relevant ones.
- 1. Jensen-kondering U, Riedel C, Jansen O. Hyperdense artery sign on computed tomography in acute ischemic stroke. World J Radiol. 2010;2 (9): 354-7. doi:10.4329/wjr.v2.i9.354 - Free text at pubmed - Pubmed citation
- 2. Chavhan GB, Shroff MM. Twenty classic signs in neuroradiology: A pictorial essay. Indian J Radiol Imaging. 19 (2): 135-45. doi:10.4103/0971-3026.50835 - Free text at pubmed - Pubmed citation
- 3. Moulin T, Cattin F, Crépin-leblond T et-al. Early CT signs in acute middle cerebral artery infarction: predictive value for subsequent infarct locations and outcome. Neurology. 1996;47 (2): 366-75. Neurology (full text) - Pubmed citation
- 4. Koo CK, Teasdale E, Muir KW. What constitutes a true hyperdense middle cerebral artery sign?. Cerebrovasc. Dis. 2000;10 (6): 419-23. doi:16101 - Pubmed citation
- 5. Manelfe C, Larrue V, von Kummer R et-al. Association of hyperdense middle cerebral artery sign with clinical outcome in patients treated with tissue plasminogen activator. Stroke. 1999;30 (4): 769-72. Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Dense middle cerebral artery sign||✗|
|Hyperdense middle cerebral arterial sign||✗|
|hyperdense middle cerebral artery sign (HMCAS)||✗|
|Dense MCA sign||✗|