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

Figures

• 

  Fig. 1.. Flowchart illustrating patient selection, application of exclusion criteria, and formation of the final study cohort. CAD, carotid artery disease; ICA, internal carotid artery; N, number of patients.

• 

  Fig. 2.. Boxplots of wall shear stress and arterial stiffness indices measured at the plaque peak level across the three stenosis groups. Patients in group 1 had <50% stenosis, those in group 2 had 50%–69% stenosis, and those in group 3 had ≥70% stenosis. Supplementary Table 1 complements the boxplot visualization by providing detailed medians, interquartile ranges, and P-values for all plaque-level measurements. WSSmean, mean wall shear stress; WSSmax, maximum wall shear stress; TUR, turbulence index; TAT, time-averaged turbulence; HC, hardness coefficient; PWV, pulse wave velocity.

• 

  Fig. 3.. Representative example of mild carotid artery stenosis (<50%), illustrating plaque-level hemodynamic parameters derived from vector flow imaging (VFI) and arterial stiffness parameters obtained using radiofrequency (RF) echo-tracking. A. VFI analysis shows velocity vector mapping. Short green and yellow vectors indicate relatively low flow velocities (maximum wall shear stress [WSSmax], 4.79 Pa; mean wall shear stress [WSSmean], 1.43 Pa). Regions of interest (ROI) for WSS measurements are placed at the plaque proximal (1–2), peak (3–4), and distal segments (5–6). Turbulence parameters in the distal segments are shown as turbulence index (TUR) 0.78% and time-averaged turbulence (TAT) 3.76%. B, C. RF echo-tracking analysis shows arterial stiffness parameters (pulse wave velocity [PWV], 5.05 m/s; hardness coefficient, 2.39).

• 

  Fig. 4.. Representative example of severe carotid artery stenosis (≥70%), illustrating plaque-level hemodynamic parameters derived from vector flow imaging (VFI) and arterial stiffness parameters obtained using radiofrequency (RF) echo-tracking. A. VFI analysis shows velocity vector mapping. Long red vectors indicate markedly increased flow velocities (maximum wall shear stress [WSSmax], 8.82 Pa; mean wall shear stress [WSSmean], 4.80 Pa). Regions of interest for WSS measurements are placed at the proximal (1–2), peak (3–4), and distal segments (5–6) of the plaque. Turbulence parameters in the distal segments are shown as turbulence index (TUR) 38.03% and time-averaged turbulence (TAT) 40%. B. A distinct vortex pattern is observed within the stenotic segment. C, D. RF echo-tracking analysis shows arterial stiffness parameters (pulse wave velocity [PWV], 7.25 m/s; hardness coefficient, 4.30), consistent with increased vessel stiffness.

• 

  Fig. 5.. Receiver operating characteristic curves of plaque peak-level parameters for detecting ≥70% carotid stenosis. Area under the curve (AUC) values are shown in the legend, and the corresponding 95% confidence intervals and optimal cutoff values are provided in Table 4. WSSmax, maximum wall shear stress; WSSmean, mean wall shear stress; TUR, turbulence index; TAT, time-averaged turbulence; HC, hardness coefficient; PWV, pulse wave velocity.

•