Dual-Energy CT Angiography for Identifying High-Risk Carotid Plaques Associated With Ipsilateral Acute Ischemic Stroke: A Retrospective Case-Control Study

Background: Early identification of high-risk carotid plaques is critical for acute ischemic stroke (AIS). Dual-energy CT angiography (DECTA) shows potential in quantifying high-risk plaque composition. Methods: Patients with carotid plaques containing non-calcified components were retrospectively selected from 1,108 patients who underwent DECTA between January and November 2024. Maximum plaque thickness (MPT), CTA-based carotid Plaque-RADS classification, and DECTA parameters, including iodine concentration (IC), slope of the spectral curve (k), and effective atomic number (Zeff), were recorded. Differences were analyzed between the ipsilateral AIS (IAIS) plaques and the control plaques without ipsilateral symptom. Logistic regression analyses were performed to identify factors associated with IAIS. Least absolute shrinkage and selection operator (LASSO) regression was used to construct an optimal diagnostic model. Results: Ninety-eight patients (mean age 62.0±11.1 years, 26.5% female) with 109 plaques were enrolled. Higher Zeff (OR = 2.31, 95% CI: 1.09?5.19, p = 0.033) was identified as an independent factor associated with IAIS. Zeff achieved higher area under the receiver operation characteristic curves (AUC) (95%CI) of 0.758 (0.670-0.847) than Plaque-RADS classification of 0.676 (0.577-0.775), although differences were not statistically significant (p > 0.05). The combined model further improved the AUC to 0.823 (95%CI: 0.744-0.901), significantly higher than Plaque-RADS (p = 0.002) and MPT (p < 0.001), while not statistically different from Zeff (p > 0.05). Conclusions: DECTA-derived parameters and the Plaque-RADS classification of carotid plaques were significantly correlated with IAIS. A higher Zeff of non-calcified component was identified as an independent plaque feature associated with IAIS.