Contrast-enhanced ultrasound for reclassification of moderate-risk carotid plaques (Plaque-RADS 3)

The Carotid Plaque-RADS system has been proposed to standardize carotid plaque evaluation recently. However, the carotid plaques classified into plaque-RADS 3 share considerable heterogeneity, which poses challenges for clinical management. This research aimed to investigate the supplementary value of contrast-enhanced ultrasound (CEUS) in assessing these moderate-risk carotid plaques designated as plaque-RADS 3.

A retrospective diagnostic analysis was conducted on 194 patients (270 plaques) who underwent carotid plaque CEUS from January 2020 to May 2024. Plaque features and patients' characteristics were retrieved. CEUS videos were independently reviewed by two senior radiologists, and intraplaque neovascularization (IPN) intensity was graded semi-quantitatively using a four point score system (0 = no enhancement; 1 = spotty enhancement; 2 = spotty and 1-2 short linear enhancements; 3 = linear enhancement traversing the plaque). Plaques were subclassified into 3a, 3b, and 3c groups based on the Carotid Plaque-RADS criteria proposed by saba et al. Differences in IPN among subgroups and their association with symptomatic plaques were analyzed using multivariate logistic regression.

Among 270 plaques, 92 were classified as 3a, 146 as 3b, and 32 as 3c. No significant differences were observed in age, gender, plaque echogenicity, length, thickness, or lumen stenosis severity among groups. Multivariate logistic regression identified luminal stenosis (OR = 2.129, p < 0.001), plaque thickness (OR = 2.429, p < 0.001), length (OR = 1.033, p < 0.001), and IPN (OR = 1.884, p = 0.012) as independent predictors of symptomatic plaques. IPN grading differed significantly across groups (p < 0.001), with 3a plaques showing a higher proportion of low (0-1) IPN scores (40.2% vs. 7.5% in 3b and 6.3% in 3c, p < 0.001). Intra- and inter-observer agreement for IPN grading was good (kappa = 0.762 and 0.704, respectively).

Approximately 40.2% of 3a plaques exhibited low IPN score, correlating with possibly reduced symptomatic risk. Despite all Plaque-RADS 3 entities described as stroke-moderate-risk, CEUS-assessed IPN enables further risk stratification-A subset of 3a plaques may warrant reclassification to lower-risk categories.

Not applicable.