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What constitutes a true hyperdense middle cerebral artery sign?
C K Koo1, E Teasdale, K W Muir
1Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK.
Cerebrovascular Diseases (Basel, Switzerland)
|November 9, 2000
Summary
The hyperdense middle cerebral artery (MCA) sign can be reliably identified using objective computed tomography criteria. This distinction is crucial for diagnosing acute ischemic stroke and guiding thrombolytic therapy.
Area of Science:
- Neuroradiology
- Stroke Imaging
- Cerebrovascular Diseases
Background:
- The hyperdense MCA sign on CT indicates potential M1 segment thrombosis in acute ischemic stroke.
- Accurate identification is vital for timely thrombolytic therapy.
- Objective criteria are needed to differentiate true positives from false positives.
Purpose of the Study:
- To establish objective criteria for identifying the hyperdense MCA sign on computed tomography.
- To differentiate true positive hyperdense MCA signs from false positives.
Main Methods:
- Analysis of brain CT scans from patients with and without hyperdense MCA signs.
- Measurement of MCA attenuation in Hounsfield units (HU) and MCA ratios.
- Comparison of absolute attenuation and ratios between cases and controls.
Main Results:
- Mean MCA attenuation was significantly higher in cases (54.0 HU) than controls (41.3 HU).
- A MCA ratio > 1.2 accurately identified true positives, predominantly associated with acute ischemic stroke.
- False positives included mature cerebral infarction or non-ischaemic pathologies.
Conclusions:
- Absolute MCA density > 43 HU and a MCA ratio > 1.2 reliably define the hyperdense MCA sign in acute ischemic stroke.
- These objective criteria distinguish true positives from normal vessels and false positives.
- Further validation in other centers is recommended.