How do age, sex, and carotid segment influence carotid ultrasonography based on vector flow imaging and radiofrequency analysis in healthy subjects?

OBJECTIVES: Atherosclerosis is influenced by hemodynamic forces and arterial stiffness. Vector flow imaging (VFI) provides assessment of wall shear stress (WSS) and turbulence, while radiofrequency-based quantitative analysis (RVQS) measures hardness coefficient (HC) and pulse wave velocity (PWV). To date, these techniques have not been applied together in a well-characterised healthy cohort. This study aimed to evaluate segmental age and sex-related differences in the carotid artery using VFI and RVQS. METHODS: Sixty healthy volunteers (30 women, 30 men; aged 20-59 years) underwent carotid ultrasonography. The common carotid artery (CCA), the bifurcation (BIF), and the internal carotid artery (ICA) segments were examined. WSS, turbulence, HC, PWV, and distension parameters were measured in each segment. Non-parametric tests were used. RESULTS: Significant segmental variation was found (p < 0.001). The BIF showed the lowest mean WSS (median = 0.84 Pa, < 0.001), the highest turbulence 3.87 (< 0.001), and the highest stiffness (HC: 3.22 < 0.001, PWV: 6.04, < 0.001). ICA had greatest distension (866 μm, < 0.001) and lowest stiffness (HC = 1.25, < 0.001, PWV: 3,83 < 0.001). Older participants had markedly stiffer arteries. PWV was higher in the older vs. younger group at both CCA (6.1 m/s vs. 4.6 m/s, p < 0.001) and BIF (7.2 vs. 4.96 m/s, p < 0.001). HC was also significantly higher in CCA and BIF (3.3 vs. 1.8, p < 0.001, 1.3 vs. 2.3, p < 0.001). Distension decreased with age in CCA and BIF (CCA: 364 vs. 560 μm, p < 0.001, BIF: 547 vs. 355 μm, p < 0.001). In contrast, WSS and turbulence did not differ significantly by age. Women exhibited higher mean WSS in the ICA (1.3 vs. 1.1 Pa, p = 0.018) and BIF (0.94 vs. 0.74 Pa, p = 0.045). Men showed slightly higher turbulence in the ICA (TAT = 1.1 vs. 0.5, p = 0.020). CONCLUSION: The study revealed marked segmental and demographic differences in atherosclerosis parameters. RVQS parameters showed significant age-related differences, whereas WSS did not vary with age in this healthy group (20-59 years), suggesting RVQS may be more sensitive for detecting subclinical early vascular change. The combined application of VFI and RVQS may provide a physiologic reference framework for assessing the carotid arteries.