Carotid pulse wave velocity estimation based on incident waves using coherent plane wave compounding ultrasound

<i>Objective</i>. Local pulse wave velocity (PWV) plays a crucial role in assessing the regional arterial elasticity. Accurate estimation of local PWV is beneficial for the risk assessment and early diagnosis of cardiovascular diseases. In this study, a method involving incident waves based on coherent plane wave compounding ultrasound (IWCU) is proposed to suppress reflected waves in pulse waves (PW) and improve the performance of transit time (TT)-based local PWV estimation.<i>Approach</i>. The ultrasonic radio frequency echo signals are collected and coherently compounded, and the PWs and central blood flow velocities at 128 beam positions are calculated, from which the incident waves (IWs) are estimated based on the Kelvin-Voigt model. Then, the time delays (TDs) of the IWs propagating are calculated, and the local PWV is finally estimated. The mean and standard deviations (MSD) of the normalized root mean squared errors NRMSEs between the presupposed and estimated TDs and PWVs were calculated for quantitatively evaluating the performance of the proposed IWCU method, and compared with those of the PWs based on coherent plane wave compounding ultrasound and the regional upstroke tracking methods in simulation experiments. The relative errors, Bland-Altman analysis and coefficient of variation (CV) were measured to further assess the accuracy, reproducibility and variability of IWCU method in<i>in vitro</i>and<i>in vivo</i>experiments.<i>Main results</i>. The IWCU method yields higher accuracy, reproducibility and lower variability for local PWV estimation. The MSD of the NRMSEs for TDs and local PWVs are 11.78 ± 0.52% and 4.10 ± 2.25%. Additionally, the mean relative error and CV are 6.10% and 12.56%, respectively.<i>Significance</i>. The IWCU method provides improved TT-based local PWV estimation, and has the potential to support future clinical diagnoses of arterial stiffness.