To explore the feasibility of using ultrasound vector flow imaging (V Flow) technology to evaluate wall shear stress (WSS) across different segments of the femoral-popliteal arteries in healthy adults, and to analyze its distribution patterns and influencing factors.

A total of 101 healthy adult volunteers (202 limbs) recruited from Peking University International Hospital between May 2022 and May 2023 were included. Using a Mindray Resona7 ultrasound system equipped with V Flow software (v2.5), the maximum wall shear stress (WSS_max) and mean wall shear stress (WSS_mean) were measured in the common femoral artery, common femoral artery bifurcation, proximal superficial femoral artery, mid superficial femoral artery, distal superficial femoral artery, and popliteal artery. Blood flow velocity (T-Max) was simultaneously measured at each site. A linear mixed model was used to analyze differences in WSS across segments and its correlation with blood flow velocity, as well as to examine the effects of gender, age, body mass index, and systolic blood pressure on WSS. Images from 30 randomly selected volunteers were independently measured by two doctors, and inter-observer consistency was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analysis.

Both WSS_max [(4.09±1.04) Pa] and WSS_mean [(0.69±0.25) Pa] at the common femoral artery bifurcation were significantly lower than those in adjacent segments (both P＜0.001). From the proximal superficial femoral artery to the popliteal artery, WSS_max and WSS_mean showed a gradually decreasing trend. WSS was significantly positively correlated with blood flow velocity (WSS_max: r=0.660, P＜0.001; WSS_mean: r=0.705, P＜0.001). Age was an independent influencing factor for WSS_mean (F=10.197, P=0.002), with WSS_mean decreasing as age increased. For every 1-year increase in age, WSS_mean decreased by 0.005 Pa (95% confidence interval: -0.008 to -0.002). Inter-observer consistency analysis showed ICC values of 0.918 for WSS_max and 0.880 for WSS_mean, and Bland-Altman analysis indicated no significant systematic measurement bias between observers.

Ultrasound V Flow technology can noninvasively and reliably measure WSS in the femoral-popliteal arteries of healthy adults. WSS is significantly lower at the common femoral artery bifurcation compared with adjacent segments, and shows a gradually decreasing trend from the proximal superficial femoral artery to the popliteal artery, consistent with hemodynamic principles. WSS is significantly positively correlated with blood flow velocity and decreases with advancing age.