Abstract
PurposeEvaluating the extent of cerebral ischemic infarction is essential for treatment decisions and assessment of possible complications in patients with acute ischemic stroke. Patients are often triaged according to image-based early signs of infarction, defined by Alberta Stroke Program Early CT Score (ASPECTS). Our aim was to evaluate interrater reliability in a large group of readers.MethodsWe retrospectively analyzed 100 investigators who independently evaluated 20 non-contrast computed tomography (NCCT) scans as part of their qualification program for the TENSION study. Test cases were chosen by four neuroradiologists who had previously scored NCCT scans with ASPECTS between 0 and 8 and high interrater agreement. Percent and interrater agreements were calculated for total ASPECTS, as well as for each ASPECTS region.ResultsPercent agreements for ASPECTS ratings was 28%, with interrater agreement of 0.13 (95% confidence interval, CI 0.09–0.16), at zero tolerance allowance and 66%, with interrater agreement of 0.32 (95% CI: 0.21–0.44), at tolerance allowance set by TENSION inclusion criteria. ASPECTS region with highest level of agreement was the insular cortex (percent agreement = 96%, interrater agreement = 0.96 (95% CI: 0.94–0.97)) and with lowest level of agreement the M3 region (percent agreement = 68%, interrater agreement = 0.39 [95% CI: 0.17–0.61]).ConclusionInterrater agreement reliability for total ASPECTS and study enrollment was relatively low but seems sufficient for practical application. Individual region analysis suggests that some are particularly difficult to evaluate, with varying levels of reliability. Potential impairment of the supraganglionic region must be examined carefully, particularly with respect to the decision whether or not to perform mechanical thrombectomy.
Highlights
The authors Noel van Horn and Helge Kniep contributed to the manuscript.Alberta Stroke Program Early computed tomography (CT) Score (ASPECTS) is a diagnostic tool for the assessment of the extent of early ischemic lesions in anterior circulation stroke and is used to select patients for mechanical thrombectomy (MT) [1, 2]
Clinical guidelines on the management of acute ischemic stroke (AIS) patients with large vessel occlusion recognize a baseline Alberta Stroke Program Early CT Score (ASPECTS) ≥ 6 as a key selection criterion for MT [4, 5]; different ASPECTS thresholds have been employed to selectively enrol patients in various clinical trials, thereby complicating stroke assessment and subsequent therapeutic considerations in the clinical routine [6,7,8,9,10,11]. Of these trials two (MR CLEAN and THRACE) independently demonstrated the benefit of MT based on non-contrast computed tomography (NCCT), the modality most commonly used for initial evaluation [4, 10, 11]
The percent agreement for total ASPECTS ratings at zero tolerance allowance was 28%, with an interrater agreement of 0.13 (Krippendorff’s α; 95% CI: 0.09–0.16; p-value < 0.01), suggesting low agreement between raters
Summary
The authors Noel van Horn and Helge Kniep contributed to the manuscript.Alberta Stroke Program Early CT Score (ASPECTS) is a diagnostic tool for the assessment of the extent of early ischemic lesions in anterior circulation stroke and is used to select patients for mechanical thrombectomy (MT) [1, 2]. As a semiquantitative grading system, ASPECTS estimates the extent of early ischemic changes on non-contrast computed tomography (CT) for ten regions within the middle cerebral artery territory and has been demonstrated to be predictive of clinical outcome [3]. K als, thereby complicating stroke assessment and subsequent therapeutic considerations in the clinical routine [6,7,8,9,10,11]. Of these trials two (MR CLEAN and THRACE) independently demonstrated the benefit of MT based on non-contrast computed tomography (NCCT), the modality most commonly used for initial evaluation [4, 10, 11]. ASPECTS has been shown to be useful in identifying patients eligible for MT who present in the late time window, selection of this subgroup is typically based on advanced imaging criteria [5, 12,13,14,15]
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