Abstract
Background and Purpose- Computed tomography (CT) perfusion (CTP) provides potentially valuable information to guide treatment decisions in acute stroke. Assessment of interobserver reliability of CTP has, however, been limited to small, mostly single center studies. We performed a large, internet-based study to assess observer reliability of CTP interpretation in acute stroke. Methods- We selected 24 cases from the IST-3 (Third International Stroke Trial), ATTEST (Alteplase Versus Tenecteplase for Thrombolysis After Ischaemic Stroke), and POSH (Post Stroke Hyperglycaemia) studies to illustrate various perfusion abnormalities. For each case, observers were presented with noncontrast CT, maps of cerebral blood volume, cerebral blood flow, mean transit time, delay time, and thresholded penumbra maps (dichotomized into penumbra and core), together with a short clinical vignette. Observers used a structured questionnaire to record presence of perfusion deficit, its extent compared with ischemic changes on noncontrast CT, and an Alberta Stroke Program Early CT Score for noncontrast CT and CTP. All images were viewed, and responses were collected online. We assessed observer agreement with Krippendorff-α. Intraobserver agreement was assessed by inviting observers who reviewed all scans for a repeat review of 6 scans. Results- Fifty seven observers contributed to the study, with 27 observers reviewing all 24 scans and 17 observers contributing repeat readings. Interobserver agreement was good to excellent for all CTP. Agreement was higher for perfusion maps compared with noncontrast CT and was higher for mean transit time, delay time, and penumbra map (Krippendorff-α =0.77, 0.79, and 0.81, respectively) compared with cerebral blood volume and cerebral blood flow (Krippendorff-α =0.69 and 0.62, respectively). Intraobserver agreement was fair to substantial in the majority of readers (Krippendorff-α ranged from 0.29 to 0.80). Conclusions- There are high levels of interobserver and intraobserver agreement for the interpretation of CTP in acute stroke, particularly of mean transit time, delay time, and penumbra maps.
Highlights
Background and PurposeComputed tomography (CT) perfusion (CTP) provides potentially valuable information to guide treatment decisions in acute stroke
Intraobserver agreement was also better with timebased maps
observers were presented with noncontrast CT
Summary
We selected 24 cases from the IST-3 (Third International Stroke Trial), ATTEST (Alteplase Versus Tenecteplase for Thrombolysis After Ischaemic Stroke), and POSH (Post Stroke Hyperglycaemia) studies to illustrate various perfusion abnormalities. We selected 24 cases from 2 clinical trials: IST-3 (imaging substudy)[15] and the ATTEST trial (Alteplase Versus Tenecteplase for Thrombolysis After Ischaemic Stroke)[16] and 1 observational study, the POSH study (Post Stroke Hyperglycaemia).[17] Patients with ischemic stroke in all of these studies had CTP performed within 6 hours of symptom onset. All raw perfusion imaging data were postprocessed by one researcher on a commercially available software platform (MiStar, Apollo Medical Imaging Technology, Melbourne, Australia) to produce maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), delay time (DT), and thresholded penumbra maps (PM). All scans covered the level of the basal ganglia and supraganglionic level required for calculation of Alberta Stroke Program Early CT (ASPECT) score
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