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Observer reliability of CT angiography in the assessment of acute ischaemic stroke: data from the Third International Stroke Trial

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http://link.springer.com/article/10.1007%2Fs00234-014-1441-0
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalNeuroradiology
Volume57
Issue number1
Early online date7 Oct 2014
DOIs
Publication statusPublished - Jan 2015

Abstract

Introduction

CT angiography (CTA) is often used for assessing patients with acute ischaemic stroke. Only limited observer reliability data exist. We tested inter- and intra-observer reliability for the assessment of CTA in acute ischaemic stroke.

Methods

We selected 15 cases from the Third International Stroke Trial (IST-3, ISRCTN25765518) with various degrees of arterial obstruction in different intracranial locations on CTA. To assess inter-observer reliability, seven members of the IST-3 expert image reading panel (>5 years experience reading CTA) and seven radiology trainees (<2 years experience) rated all 15 scans independently and blind to clinical data for: presence (versus absence) of any intracranial arterial abnormality (stenosis or occlusion), severity of arterial abnormality using relevant scales (IST-3 angiography score, Thrombolysis in Cerebral Infarction (TICI) score, Clot Burden Score), collateral supply and visibility of a perfusion defect on CTA source images (CTA-SI). Intra-observer reliability was assessed using independently repeated expert panel scan ratings. We assessed observer agreement with Krippendorff’s-alpha (K-alpha).

Results

Among experienced observers, inter-observer agreement was substantial for the identification of any angiographic abnormality (K-alpha = 0.70) and with an angiography assessment scale (K-alpha = 0.60–0.66). There was less agreement for grades of collateral supply (K-alpha = 0.56) or for identification of a perfusion defect on CTA-SI (K-alpha = 0.32). Radiology trainees performed as well as expert readers when additional training was undertaken (neuroradiology specialist trainees). Intra-observer agreement among experts provided similar results (K-alpha = 0.33–0.72).

Conclusion

For most imaging characteristics assessed, CTA has moderate to substantial observer agreement in acute ischaemic stroke. Experienced readers and those with specialist training perform best.

    Research areas

  • Cerebral angiography, Stroke, Inter-observer variability, Intra-observer variability, TISSUE-PLASMINOGEN-ACTIVATOR, NONCONTRAST CT, THROMBOLYSIS, PERFUSION, SCORE, AGREEMENT, UTILITY, EXTENT, KAPPA, SCALE

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