[Detectability of new medial infarcts by CT: appearance of ischemic signs]

To evaluate the detectability of acute middle cerebral artery (MCA) infarctions by CT with regard to the time interval after symptom onset and to the infarction size. Analysis of the chronological appearance of signs of ischaemia.

Two examiners retrospectively and independently evaluated CT scans from 171 patients with acute MCA infarctions performed within 24 hours after onset of symptoms.

92, respectively 87% of the Infarctions were correctly diagnosed. The detection rate did not increase after the first hour after onset of symptoms. All MCA infarctions involving the lentiform nucleus, but only 83% of the infarctions covering < 33% of the MCA area, were recognised. The hyperdense middle cerebral artery sign (HMCA5) was present in 75% of the infarctions in the first 90 minutes and in 15% from hour 12 to 24. Hypodensity of the lentiform nucleus appeared within 150 minutes, hypodensity of the convexity cortex at the earliest 60 minutes after onset of symptoms.

The detection rate of acute MCA infarctions corresponds with the infarction size, but does not significantly change after the first hour after symptom onset.