Quantitative Ultrasound SWE of Carotid Plaque in Symptomatic and Asymptomatic Patients: A Systematic Review and Meta-Analysis

Background/Objectives: Ultrasound shear-wave elastography (SWE) enables quantitative assessment of tissue stiffness and may provide a non-invasive biomarker of carotid plaque vulnerability. This study aimed to evaluate the ability of SWE to differentiate symptomatic from asymptomatic carotid plaques and to assess its reproducibility. Methods: A systematic search of PubMed, Web of Science, EMBASE, and the Cochrane Library was conducted in the last ten years until January 2026 for publications evaluating carotid plaques using ultrasound SWE. Inclusion criteria required original publications that used quantitative ultrasound SWE parameters for the evaluation of carotid plaque in symptomatic and asymptomatic patients and/or investigated the reproducibility of SWE parameters for carotid plaques; non-carotid studies, non-original articles, and studies not comparing symptomatic versus asymptomatic plaques or not reporting reproducibility were excluded. Fourteen studies comprising 1781 carotid plaques were included. Quantitative SWE measurements were meta-analyzed using random effects. Differences between symptomatic and asymptomatic plaques were assessed using standardized mean differences (SMDs). The reproducibility of SWE measurements was evaluated using pooled correlation coefficients. Publication bias was evaluated using funnel plots and Egger’s regression test. Results: Ten studies including 1246 plaques compared SWE stiffness between symptomatic (n = 472) and asymptomatic plaques (n = 774). The meta-analysis demonstrated significantly lower stiffness values in symptomatic plaques compared with asymptomatic plaques (SMD −1.10, p < 0.001). Reproducibility analysis of correlation coefficients extracted from seven studies demonstrated excellent agreement for SWE measurements (r = 0.92, n = 602). Heterogeneity was observed across the included studies. No statistically significant evidence of publication bias was detected. Conclusions: Ultrasound SWE is a promising approach for assessing carotid plaque vulnerability, with lower SWE stiffness observed in symptomatic plaques compared to asymptomatic plaques. This finding should be interpreted with consideration of methodological heterogeneity and the cross-sectional nature of the available assessed evidence. Further prospective studies with standardized imaging protocols and longitudinal follow-up are needed to determine clinically applicable stiffness thresholds and evaluate the prognostic value of ultrasound SWE in cerebrovascular risk stratification.