Tilt-Corrected Region Boundaries May Enhance the Alberta Stroke Program Early Computed Tomography Score for Less Experienced Raters.

BACKGROUND

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to quantify early ischemic changes in the anterior circulation but has limited inter-rater reliability.

AIMS

We investigated whether application of 3-dimensional boundaries outlining the ASPECTS regions improves inter-rater reliability and accuracy.

METHODS

We included all patients from our DEFUSE 2 database who had a pretreatment noncontrast computed tomography scan (NCCT) of acceptable quality. Six raters (2 neuroradiologists, 2 vascular neurologists, and 2 neurology residents) scored ASPECTS of each NCCT without ("CT-native") and with the superimposed boundary template ("CT-template"). Gold-standard ASPECTS were generated by the 2 neuroradiologists through joint adjudication. Inter-rater reliability and accuracy were assessed using the intraclass correlation coefficient (ICC) for full-scale agreements and Gwet's AC1 for dichotomized (ASPECTS 0-6 vs 7-10) agreements.

RESULTS

Eighty-two patients were included. Inter-rater reliability improved with higher training level for both CT-native (ICC = .15, .31, .54 for residents, neurologists, and radiologists, respectively) and CT-template (ICC = .18, .33, .56). Use of the boundary template improved correlation with the gold-standard for one resident on full-scale agreement (ICC increased from .01 to .31, P = .01) and another resident on dichotomized agreement (AC1 increased from .36 to .64, P = .01), but resulted in no difference for other raters. The template did not improve ICC between raters of the same training level.

CONCLUSIONS

Inter-rater reliability of ASPECTS improves with physician training level. Standardized display of ASPECTS region boundaries on NCCT does not improve inter-rater reliability but may improve accuracy for some less experienced raters.