Performance of Automated Attenuation Measurements at Identifying Large Vessel Occlusion Stroke on CT Angiography

Lars Kellert,Thomas Liebig,Jan Rémi,Paul Reidler,Moriz Herzberg,Lena Stueckelschweiger,Katharina Feil,Konstantinos Dimitriadis,Steffen Tiedt,Matthias P Fabritius,Daniel Puhr-Westerheide,Wolfgang G Kunz

doi:10.1007/s00062-020-00956-5

Abstract

PurposeComputed tomography angiography (CTA) is routinely used to detect large-vessel occlusion (LVO) in patients with suspected acute ischemic stroke; however, visual analysis is time consuming and prone to error. To evaluate solutions to support imaging triage, we tested performance of automated analysis of CTA source images (CTASI) at identifying patients with LVO.MethodsStroke patients with LVO were selected from a prospectively acquired cohort. A control group was selected from consecutive patients with clinically suspected stroke without signs of ischemia on CT perfusion (CTP) or infarct on follow-up. Software-based automated segmentation and Hounsfield unit (HU) measurements were performed on CTASI for all regions of the Alberta Stroke Program Early CT score (ASPECTS). We derived different parameters from raw measurements and analyzed their performance to identify patients with LVO using receiver operating characteristic curve analysis.ResultsThe retrospective analysis included 145 patients, 79 patients with LVO stroke and 66 patients without stroke. The parameters hemispheric asymmetry ratio (AR), ratio between highest and lowest regional AR and M2-territory AR produced area under the curve (AUC) values from 0.95–0.97 (all p < 0.001) for detecting presence of LVO in the total population. Resulting sensitivity (sens)/specificity (spec) defined by the Youden index were 0.87/0.97–0.99. Maximum sens/spec defined by the specificity threshold ≥0.70 were 0.91–0.96/0.77–0.83. Performance in a small number of patients with isolated M2 occlusion was lower (AUC: 0.72–0.85).ConclusionAutomated attenuation measurements on CTASI identify proximal LVO stroke patients with high sensitivity and specificity. This technique can aid in accurate and timely patient selection for thrombectomy, especially in primary stroke centers without CTP capacity.

Highlights

Detection of large vessel occlusion (LVO) in patients with suspected ischemic stroke is the most critical diagnostic challenge in acute stroke imaging
In most stroke treating facilities, single-phase computed tomography angiography (CTA) is the primary imaging modality to detect LVO and prompt further treatment or transfer to comprehensive stroke centers [6]. The latter is a common scenario in primary stroke centers (PSC) with often limited imaging capacities and imaging interpretation by less experienced readers compared to high-volume centers [6, 7]
To address the clinical value of automated attenuation analysis in single-phase CTA data, we evaluated its performance in detecting stroke patients with LVO of the anterior circulation and consequent ischemia in the medial cerebral artery (MCA) territory among a population of patients with suspected ischemic stroke

Summary

Introduction

Detection of large vessel occlusion (LVO) in patients with suspected ischemic stroke is the most critical diagnostic challenge in acute stroke imaging. In most stroke treating facilities, single-phase computed tomography angiography (CTA) is the primary imaging modality to detect LVO and prompt further treatment or transfer to comprehensive stroke centers [6]. The latter is a common scenario in primary stroke centers (PSC) with often limited imaging capacities and imaging interpretation by less experienced readers compared to high-volume centers [6, 7]. Improving diagnostic confidence at single-phase CTA could ensure correct and timely stroke triage, for example to decide patient transfer

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Results

Conclusion