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

Abstract

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.

Fig 1.

A 75-year-old male patient with acute ischemic stroke. At initial CTA evaluation, occlusion of 1 of the M2 segment branches of the left middle cerebral artery (arrows on all slices) was missed. Consecutive axial CTA slices in a caudocranial direction (A–D) show a contrast filling defect in a branch of the left M2 segment (arrows in C and D). Note that 2 adjacent branches of the left M2 segment show normal contrast filling on all slices (arrowheads).

Fig 2.

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).