Abstract W MP18: NCCT ASPECTS Underestimates Infarct Core in Early Presenters with Poor Collateral Status

Abstract

Background and Purpose: Noncontrast CT (NCCT) identifies early ischemic change that can predict irreversible ischemic injury. However DWI is more sensitive than NCCT in detection of early ischemic lesion. Our aim was to investigate the factors that influence discrepancy in early ischemic change detection between CT and DWI among good NCCT scan. Methods: We collected consecutive 167 ischemic stroke patients with occlusion of ICA and/or MCA M1 diagnosed by CTA and DWI within 6h of onset (last seen normal, LNT) between August 2004 and February 2013. Alberta Stroke Program Early Computed Tomography Score (ASPECTS) was used to evaluate discrepancy between lesions on NCCT and DWI MR. We identified 109 patients with a good NCCT scan defined as ASPECTS 6-10. Discrepancy between NCCT and DWI was when DWI ASPECTS was 0-5 and no discrepancy was when DWI ASPECTS was 6-10. Regional leptomeningeal collateral (rLMC) score by CTA was used to evaluate collateral status. Results: We reviewed 109 patients (mean age 67.5 ± 12.5 years) with median baseline National Institutes of Health Stroke Scale (NIHSS) 14 (interquartile range, 10-19). Discrepancy group (N=40, 36.7%) had shorter time from LNT to CT (median 98 vs 132 min, p=0.013), higher score of initial NIHSS (median 17 vs 13, p=0.013), lower rLMC score (median 10.5 vs 14, p<0.001). There was no significant difference from CT to DWI time (median 41 vs 40 min) between both groups. In a multivariable logistic regression analysis, time from LNT to CT (OR 0.99; 95% CI 0.99-1.00; P=0.05), rLMC score (OR 0.21; 95% CI 0.08-0.56; P=0.002) were independently associated with the discrepancy group. Conclusion: Discrepancy between CT and DWI is common in patients with acute anterior circulation ischemic stroke. This discrepancy is more apparent when patients present early and have poor collaterals.