Impact of Lesion Load Thresholds on Alberta Stroke Program Early Computed Tomographic Score in Diffusion-Weighted Imaging

Julian Schröder; Bastian Cheng; Caroline Malherbe; Martin Ebinger; Martin Köhrmann; Ona Wu; Dong-Wha Kang; David S Liebeskind; Thomas Tourdias; Oliver C Singer; Bruce Campbell; Marie Luby; Steven Warach; Jens Fiehler; André Kemmling; Jochen B Fiebach; Christian Gerloff; Götz Thomalla

doi:10.3389/fneur.2018.00273

Impact of Lesion Load Thresholds on Alberta Stroke Program Early Computed Tomographic Score in Diffusion-Weighted Imaging

Front Neurol. 2018 Apr 23:9:273. doi: 10.3389/fneur.2018.00273. eCollection 2018.

Authors

Julian Schröder¹, Bastian Cheng¹, Caroline Malherbe^{1

2}, Martin Ebinger^{3

4}, Martin Köhrmann⁵, Ona Wu⁶, Dong-Wha Kang⁷, David S Liebeskind⁸, Thomas Tourdias⁹, Oliver C Singer¹⁰, Bruce Campbell¹¹, Marie Luby¹², Steven Warach¹³, Jens Fiehler¹⁴, André Kemmling¹⁵, Jochen B Fiebach³, Christian Gerloff¹, Götz Thomalla¹

Affiliations

¹ Klinik und Poliklinik für Neurologie, Kopf- und Neurozentrum, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
² Institut für Computational Neuroscience, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
³ Centrum für Schlaganfallforschung Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.
⁴ Klinik für Neurologie, Charité - Universitätsmedizin Berlin, Berlin, Germany.
⁵ Klinik für Neurologie, Universität Erlangen-Nürnberg, Erlangen, Germany.
⁶ Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States.
⁷ Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
⁸ Neurovascular Imaging Research Core, Department of Neurology, University of California, Los Angeles, Los Angeles, CA, United States.
⁹ Service de Neuroimagerie Diagnostique de Thérapeutique, Centre Hospitalier Universitaire de Bordeaux, Université de Bordeaux, Bordeaux, France.
¹⁰ Klinik für Neurologie, Universitätsklinikum Frankfurt, Frankfurt, Germany.
¹¹ Department of Medicine and Neurology, Melbourne Brain Centre at the Royal Melbourne Hospital, University of Melbourne, Melbourne, VIC, Australia.
¹² National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States.
¹³ Department of Neurology, Dell Medical School, University of Texas at Austin, Austin, TX, United States.
¹⁴ Klinik und Poliklinik für Neuroradiologische Diagnostik und Intervention, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
¹⁵ Institut für Neuroradiologie, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany.

Abstract

Background and aims: Assessment of ischemic lesions on computed tomography or MRI diffusion-weighted imaging (DWI) using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is widely used to guide acute stroke treatment. However, it has never been defined how many voxels need to be affected to label a DWI-ASPECTS region ischemic. We aimed to assess the effect of various lesion load thresholds on DWI-ASPECTS and compare this automated analysis with visual rating.

Materials and methods: We analyzed overlap of individual DWI lesions of 315 patients from the previously published predictive value of fluid-attenuated inversion recovery study with a probabilistic ASPECTS template derived from 221 CT images. We applied multiple lesion load thresholds per DWI-ASPECTS region (>0, >1, >10, and >20% in each DWI-ASPECTS region) to compute DWI-ASPECTS for each patient and compared the results to visual reading by an experienced stroke neurologist.

Results: By visual rating, median ASPECTS was 9, 84 patients had a DWI-ASPECTS score ≤7. Mean DWI lesion volume was 22.1 (±35) ml. In contrast, by use of >0, >1-, >10-, and >20%-thresholds, median DWI-ASPECTS was 1, 5, 8, and 10; 97.1% (306), 72.7% (229), 41% (129), and 25.7% (81) had DWI-ASPECTS ≤7, respectively. Overall agreement between automated assessment and visual rating was low for every threshold used (>0%: κ_w = 0.020 1%: κ_w = 0.151; 10%: κ_w = 0.386; 20% κ_w = 0.381). Agreement for dichotomized DWI-ASPECTS ranged from fair to substantial (≤7: >10% κ = 0.48; >20% κ = 0.45; ≤5: >10% κ = 0.528; and >20% κ = 0.695).

Conclusion: Overall agreement between automated and the standard used visual scoring is low regardless of the lesion load threshold used. However, dichotomized scoring achieved more comparable results. Varying lesion load thresholds had a critical impact on patient selection by ASPECTS. Of note, the relatively low lesion volume and lack of patients with large artery occlusion in our cohort may limit generalizability of these findings.

Keywords: Alberta stroke program early computed tomography score; acute stroke treatment; computed tomography; magnetic resonance imaging; stroke.