Hemodynamic Wall Shear Stress Measurements Using Ultrasound Feature Tracking Algorithm

Accurate wall shear rate (WSR) measurements are important for the early diagnosis of cardiovascular disease progression and acute events, such as atherosclerotic plaque rupture and aneurysm rupture. The Kanade-Lucas-Tomasi (KLT) feature tracking is an ultrasound imaging technique and competitive candidate for WSR measurements. In this study, we hypothesized that the accuracy of WSR measurements can be improved using KLT feature tracking. Thereby, we aimed to evaluate the accuracy of KLT feature tracking for flow velocities and WSR measurements by comparing the results with those from the conventional two-dimensional ultrasound speckle tracking (2D-UST) technique. An in-vitro flow experiment was performed using a flow phantom, and blood flow velocity profiles were generated using KLT feature tracking and the 2D-UST algorithm. A quantitative error analysis was performed for the flow velocities and WSRs measured using both methods based on the analytical values. The WSRs measured using KLT feature tracking demonstrated significantly higher agreement with the analytical values than those measured using 2D-UST. The measured WSRs using KLT feature tracking were found to match the analytical values with absolute errors of 0.9% and 14.4% at the top and bottom luminal walls, respectively. By contrast, the estimated WSRs using the 2D-UST algorithm were found to be in poor agreement with the analytical values, with absolute errors of 80.7% and 67.1% at the top and bottom luminal walls, respectively. Therefore, our results demonstrate the feasibility of KLT feature tracking for clinical application of in-vivo wall shear stress measurements.