Non-enhanced Brain CT (NECT) offers low yield in terms of its diagnostic utility for acute ischemic stroke (AIS), with sensitivities less than 67% at 3 hours out from symptom onset.
A hyperdense middle cerebral artery (MCA) sign may represent acute thrombus and predicts impending large territorial infarct of poor prognosis (*see images of MCA Sign (left) and subsequent territorial edema representing infarct (right) below).
While MCA Signs occur somewhat rarely, this finding is one of the earliest and most useful indicators of probable (clinical) stroke on NECT, and should be a recognizable hallmark for the emergency physician.
Note that hyperdense MCA's can mimic a thrombus and actually represent atherosclerotic calcifications.
References
Latchaw RE, et al. Recommendations for Imaging of Acute Ischemic Stroke: A Scientific Statement from the American Heart Association. Stroke 2009; 40: 3646-3678.
Neuroradiology Teaching Files. Part Forty-five. Hyperdense MCA Sign. uhrad.com.
