CT Angiography in Evaluating Large-Vessel Occlusion in Acute Anterior Circulation Ischemic Stroke: Factors Associated with Diagnostic Error in Clinical Practice

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This study included 520 consecutive patients with a clinical diagnosis of acute ischemic stroke (49.4% men; mean age, 72 years) who underwent CTA to evaluate large-vessel occlusion of the proximal anterior circulation. CTA scans were retrospectively reviewed by a consensus panel of 2 neuroradiologists. The prevalence of large-vessel occlusion was 16% (84/520 patients); 20% (17/84) of large-vessel occlusions were missed atthe initial CTA evaluation. In multivariate analysis, non-neuroradiologists were more likely to miss large-vessel occlusion compared with neuroradiologists, and occlusions of the M2 segment were more likely to be missed compared with occlusions of the distal internal carotid artery and/or M1 segment. Calcified emboli were present in 4 of 17 (24%) initially missed or misinterpreted large-vessel occlusions.

Abstract

A 70-year-old male patient with acute ischemic stroke. At initial CTA evaluation, LVO due to a calcified embolus in the M2 segment of the left middle cerebral artery (arrows in CTA image, A; and in a noncontrast head CT image, B) was misinterpreted as clinically irrelevant calcification. Follow-up MR imaging (FLAIR image, C; and diffusion-weighted image, D) 1 day after CTA reveals infarction in the left middle cerebral artery territory (arrows).

BACKGROUND AND PURPOSE

It is currently not completely clear how well radiologists perform in evaluating large-vessel occlusion on CTA in acute ischemic stroke. The purpose of this study was to investigate potential factors associated with diagnostic error.

MATERIALS AND METHODS

Five hundred twenty consecutive patients with a clinical diagnosis of acute ischemic stroke (49.4% men; mean age, 72 years) who underwent CTA to evaluate large-vessel occlusion of the proximal anterior circulation were included. CTA scans were retrospectively reviewed by a consensus panel of 2 neuroradiologists. Logistic regression analysis was performed to investigate the association between several variables and missed large-vessel occlusion at the initial CTA interpretation.

RESULTS

The prevalence of large-vessel occlusion was 16% (84/520 patients); 20% (17/84) of large-vessel occlusions were missed at the initial CTA evaluation. In multivariate analysis, non-neuroradiologists were more likely to miss large-vessel occlusion compared with neuroradiologists (OR = 5.62; 95% CI, 1.06–29.85; P = .04), and occlusions of the M2 segment were more likely to be missed compared with occlusions of the distal internal carotid artery and/or M1 segment (OR = 5.69; 95% CI, 1.44–22.57; P = .01). There were no calcified emboli in initially correctly identified large-vessel occlusions. However, calcified emboli were present in 4 of 17 (24%) initially missed or misinterpreted large-vessel occlusions.

CONCLUSIONS

Several factors may have an association with missing a large-vessel occlusion on CTA, including the CTA interpreter (non-neuroradiologists versus neuroradiologists), large-vessel occlusion location (M2 segment versus the distal internal carotid artery and/or M1 segment), and large-vessel occlusion caused by calcified emboli. Awareness of these factors may improve the accuracy in interpreting CTA and eventually improve stroke outcome.

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