To compare the value of high-frame-rate contrast-enhanced ultrasound (H-CEUS) in the evaluation of neovascularization in carotid atherosclerotic plaques compared with conventional contrast-enhanced ultrasound.

A retrospective analysis was performed on 27 patients with 33 carotid artery plaques at the First Medical Center of Chinese PLA General Hospital from October 2019 to February 2020. Both conventional contrast-enhanced ultrasound and H-CEUS were performed on all the subjects, and two observers analyzed the ultrasound images to give evaluation results and classification. Observation indicators includes plaque thickness, plaque echo, whether the surface fiber cap was complete or not, and whether there were new blood vessels and new blood vessel structures in the plaque post-contrast. Image characteristics and classification results of the two modalities were statistically analyzed. Count data were compared using the χ² test and the consistency was evaluated using the Kappa test.

The evaluation results of the two observers on the presence or absence of new blood vessels in the plaque between the two modalities were consistent, and there was no significant difference between them (P>0.05). H-CEUS was significantly better than conventional contrast-enhanced ultrasound in displaying neovascular structures (observer A: χ²=4.11, P=0.040; observer B: χ²=4.20, P=0.040), but there was no significant difference in the grading of neovascularization in the plaque (P>0.05). For conventional contrast-enhanced ultrasound, the Kappa coefficient of agreement between the two observers was 0.6716 (95% confidence interval: 0.4737~0.8695) for conventional contrast-enhanced ultrasound, and 0.7500 (95% confidence interval: 0.5681~0.9319) for H-CEUS; compared with conventional contrast-enhanced ultrasound, the consistency between two observers was significantly improved when using H-CEUS.

H-CEUS can make the neovascularization and vascular structure in plaque more clear, and the consistency of the evaluation results between different observers is obviously improved. H-CEUS has appreciated clinical application value in evaluating the neovascularization in plaque.