Linking Carotid Plaque Immune Subtypes to Multimodal Ultrasound Features.

RATIONALE AND

OBJECTIVES

To establish a plaque immune microenvironment classification system and explore whether multimodal ultrasound may aid in the non-invasive identification of high-risk subtypes.This exploratory study investigated the association between PCA-derived immune subtypes and multimodal ultrasound features.

METHODS

This prospective study included 50 patients undergoing carotid endarterectomy (CEA). Seven immunohistochemistry (IHC) markers: interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-2, cluster of differentiation 11b (CD11b), myeloperoxidase (MPO), and microvessel density (MVD) were assessed. Principal component analysis (PCA) and hierarchical clustering defined immune subtypes. Preoperative conventional ultrasound and contrast-enhanced ultrasound (CEUS) evaluated vulnerability score, plaque thickness, and intraplaque neovascularization (IPN) grade.

RESULTS

Hierarchical clustering revealed three functional modules: core pro-inflammatory (TNF-α, IL-6, IL-2, IFN-γ), angiogenesis-macrophage (CD11b, MVD), and MPO-alone. PCA classified 50 plaques into four subtypes: Type I (inflammation-dominated, n=8), Type II (angiogenesis-dominated, n=14), Type III (high inflammation and high angiogenesis, n=11), and Type IV (stable, n=17). Type III plaques had highest inflammatory factors and MVD, with 45.5% experiencing recent ischemic events. Ultrasound vulnerability score correlated with IL-6 (r=0.54) and MVD (r=0.52); IPN grade correlated strongly with MVD (r=0.69). Type III showed a "high-risk triad": high vulnerability score (median 5.0), increased thickness (0.45 cm), and high IPN grade (45.5% grade 3). Type II had isolated high IPN grade (71.4% ≥ grade 2).

CONCLUSION

PCA-based immune subtyping of carotid plaques appears feasible. Multimodal ultrasound, particularly vulnerability score and IPN grade, may aid in the non-invasive identification of high-risk subtypes, suggesting a potential imaging strategy for plaque risk stratification.