Diagnostic performance of vector flow imaging–derived wall shear stress and radiofrequency echo-tracking–derived arterial stiffness indices in severe carotid stenosis

Purpose: This study aimed to evaluate the diagnostic performance of vector flow imaging (VFI)–derived hemodynamic parameters and radiofrequency echo-tracking–derived arterial stiffness indices (RF-ASI) for detecting severe carotid artery stenosis.Methods: This prospective, single-center observational study included 90 patients with carotid artery disease examined between May and July 2024. Stenosis severity was categorized as <50%, 50%–69%, and ≥70% according to the Society of Radiologists in Ultrasound (SRU) Doppler criteria. In patients with stenosis ≥50%, severity was confirmed using digital subtraction angiography, computed tomography angiography, or magnetic resonance angiography. At the plaque level, VFI-derived wall shear stress (WSS) and turbulence metrics, as well as RF-ASI, were measured. Correlation analyses, group comparisons, and receiver operating characteristic analysis were performed to evaluate each parameter’s ability to detect ≥70% stenosis.Results: Among the 90 patients (mean age, 70.4±8.7 years; 55.6% male), peak-segment mean wall shear stress (WSSmean) demonstrated the strongest correlation with stenosis severity (rₛ=0.87, P<0.001). WSSmean also showed the highest diagnostic performance for detecting ≥70% stenosis (area under the curve, 0.96; 95% confidence interval, 0.92 to 0.99; cutoff, 2.25 Pa), compared with other VFI-derived metrics and RF-ASI. Segmental analysis revealed that WSS values were highest at the plaque peak, whereas turbulence-related metrics were more pronounced in distal segments. In SRU-discordant cases (7 of 90), WSSmean agreed with anatomic imaging–based classification (≥70% vs. <70%) in six of seven lesions.Conclusion: VFI-derived WSSmean demonstrated the highest diagnostic performance for detecting severe (≥70%) carotid stenosis. In contrast, RF-ASI showed limited discriminatory ability and may primarily reflect global arterial stiffness rather than focal plaque severity.