Plaque biomarkers from high-frame rate vector flow imaging and shear wave elastography in mild carotid stenosis

Abstract

Purpose: This study aimed to investigate the association of carotid plaque biomechanical parameters and elasticity-measured using high-frame rate vector flow imaging (VFI) and shear wave elastography (SWE)-with the occurrence of ipsilateral ischemic stroke in patients with mild stenosis.

Methods: The study included 122 patients with mild carotid stenosis involving a single plaque between September 2023 and April 2024 who underwent B-mode ultrasound, high-frame rate VFI, and SWE examinations. Based on head computed tomography or magnetic resonance imaging findings, participants were classified as symptomatic (with ipsilateral ischemic lesions) or asymptomatic. Wall shear stress, oscillatory shear index, and turbulence (Tur) index were quantified on both downstream and upstream plaque surfaces, and the Young modulus (YM) was measured for distinct plaque regions. Multivariate logistic regression models were employed to evaluate correlations between these imaging-derived parameters and ipsilateral ischemic stroke.

Results: A higher Tur index on the plaque's downstream surface and a lower mean YM within the plaque were significantly associated with ipsilateral ischemic stroke in patients with mild carotid stenosis. Moreover, the combined use of high-frame rate VFI and SWE demonstrated superior predictive performance for stroke risk compared with either modality alone.

Conclusion: High-frame rate VFI and SWE enable detection of biomechanical features and stiffness in high-risk plaques among patients with mild carotid stenosis. Their combined application may yield valuable non-invasive biomarkers for stratifying stroke risk in this population.

Keywords: Carotid atherosclerotic plaque; High-frame rate vector flow imaging; Ischemic stroke; Mild carotid stenosis; Shear wave elastography.

Fig. 1.. Flowchart of patient inclusion and exclusion.

n, number of patients.

Fig. 2.. Vector flow imaging (VFI) measurements of the upstream and downstream carotid plaque surfaces.

A. Wall shear stress (WSS), oscillatory shear index (OSI), and turbulence (Tur) index were measured at the upstream surface. B. WSS, OSI, and Tur index were measured at the downstream surface. Blue dots mark locations for WSS and OSI measurements; green squares denote regions for Tur index calculation. Vel, velocity; ROI, region of interest; T, time; TA, time average.

Fig. 3.. Shear wave elastography (SWE) measurements of the carotid plaques.

A. B-mode ultrasound image of the plaque is shown. B. SWE measurement of the entire plaque is presented. C. SWE measurements at the downstream (a) and upstream (b) regions are shown: white solid lines delineate the plaque margins, while white circles indicate regions of interest for mean Young modulus calculation.