RT Journal Article SR Electronic T1 Interobserver agreement in assessing early CT signs of middle cerebral artery infarction. JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 1743 OP 1748 VO 17 IS 9 A1 R von Kummer A1 R Holle A1 U Gizyska A1 E Hofmann A1 O Jansen A1 D Petersen A1 M Schumacher A1 K Sartor YR 1996 UL http://www.ajnr.org/content/17/9/1743.abstract AB PURPOSE To assess the reliability of detecting signs of hemispheric infarction on CT scans obtained within 6 hours of the onset of symptoms.METHODS A neuroradiologist selected 12 normal and 33 abnormal CT studies showing the hyperdense middle cerebral artery sign (HMCAS) (n = 10), brain swelling (n = 22), and parenchymal hypodensity (n = 33) from two series of 750 patients with recent onset of middle cerebral artery stroke. These selections served as the reference source for a nonblinded analysis of the initial and follow-up CT scans. Six neuroradiologists then reviewed the CT scans twice, first blinded then not blinded to clinical symptoms. They assessed the signs of infarction for each hemisphere separately and estimated the volume of abnormal parenchymal hypodensity in increments of 20% within the territory of the middle cerebral artery.RESULTS Unblinding the reviewers did not change interobserver agreement significantly. The chance adjusted agreement was moderate to substantial: kappa = .62 (95% confidence interval [CI], .46 to .78) and kappa = .57 (95% CI, .33 to .81) for the HMCAS of the right and left hemisphere, respectively; kappa = .59 (95% CI, .47 to .71) and kappa = .56 (95% CI, .38 to .74) for focal brain swelling of the right and left hemisphere, respectively; and kappa = .58 (95% CI, .50 to .66) and kappa = .55 (95% CI, .32 to .67) for parenchymal hypodensity of the right and left hemisphere, respectively. Weighted kappa was .65 and .57 for the estimation of the hypodense tissue volume in the right and left hemisphere, respectively. Agreement with the reference source ranged from 73% to 93% for all variables and both hemispheres.CONCLUSION Even with no clinical information, neuroradiologists can assess subtle CT signs of cerebral infarction within the first 6 hours of symptom onset with moderate to substantial interobserver agreement.