Hypodensity of >1/3 middle cerebral artery territory versus Alberta Stroke Programme Early CT Score (ASPECTS) -: Comparison of two methods of quantitative evaluation of early CT changes in hyperacute ischemic stroke in the community setting

Background - The one third middle cerebral artery territory (1/3 MCA) method and the Alberta Stroke Program Early CT Score ( ASPECTS) were used to detect significant early ischemic changes ( EIC) on CT brain of acute stroke patients. We sought to compare the reliability of the 2 methods in routine clinical practice. Methods - Eighty consecutive patients admitted to a community hospital in Hong Kong with suspected acute ischemic stroke and a CT brain scan performed within 6 hours of symptom onset were included. Five blinded observers ( 1 neurologist, 2 general radiologists, and 2 neuroradiologists) independently evaluated the scans, using the ATLANTIS/CT Summit criteria for >1/3 MCA involvement, and ASPECTS less than or equal to7. Kappa statistics were used to determine interobserver agreement. Results - Significant EIC were present in 11.4% of the scans with the 1/3 MCA method, and 19.4% with ASPECTS. For >1/3 MCA involvement, all observers agreed in 57 cases (71%), with moderate interobserver agreement (kappa = 0.49). For ASPECTS less than or equal to7, all observers agreed in 34 cases (42%), with fair interobserver agreement (kappa = 0.34). After prevalence and bias adjustments, substantial (prevalence-adjusted bias-adjusted kappa [PABAK] = 0.74) and moderate ( PABAK = 0.44) agreements were found for the 1/3 MCA method and ASPECTS respectively. Conclusions - The 1/3 MCA method was more reliable in detecting significant EIC on CT brain within 6 hours of stroke onset in routine clinical practice, whereas ASPECTS was able to detect significant EIC in a higher proportion of these early scans.