Improved Robustness of Ultrasound Speckle Decorrelation-Based Wall Shear Rate Estimation Using Incoherent Multi-Angle...

Accurate estimation of vascular wall shear rate (WSR) is important for assessing local hemodynamic conditions associated with cardiovascular disease. Ultrasound speckle decorrelation (SDC), combined with singular value decomposition-based clutter filtering, enables WSR estimation from transverse-view ultrasound imaging by exploiting decorrelation induced by through-blood motion. However, the accuracy and stability of SDC-based WSR estimates can be limited by noise, residual clutter and spatial variability near the vessel wall. In this study, we investigate the use of incoherent multi-angle plane-wave (PW) compounding to improve the robustness of SDC-based WSR estimation. SDC measurements obtained from multiple angles are incoherently averaged to reduce random estimation variability while preserving flow-induced decorrelation. The proposed approach was evaluated using ultrasound simulations, in vitro flow experiments under steady and pulsatile conditions and an in vivo human study of the brachial artery. WSR estimates obtained using a single PW acquisition were compared with those derived from five-angle incoherent compounding (IC). The results demonstrate that IC produces smoother velocity profiles and more spatially consistent WSR estimates than single PW imaging. Quantitative analysis showed reduction of normalized root-mean-square error in simulations and in vitro experiments, while in vivo measurements exhibited decrease of spatial variability and improved smoothness of WSR distributions along the vessel wall. These findings indicate that incoherent multi-angle compounding enhances the robustness of SDC-based WSR estimation.