system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Dense middle cerebral aery (MCA) Sign in brain is seen in
assistant
The correct answer is  The hyperdense MCA sign refers to the focally increased density of the middle cerebral aery on CT and is a direct visualization of thromboembolic material within the lumen. It is thus the earliest visible sign of MCA infarction as it is seen within 90 minutes after the event - acute infarct. It is the longitudinal equivalent of the MCA dot sign and hyperdense basilar tip sign.