Study On The Influencing Factors Of The Accuracy Of Carotid Pulse Wave Velocity Detection And The Improvement Of Detection Method

With the improvement of the living standards, the morbidity and mortality of cardiovascular and cerebrovascular disease, such as coronary disease, stroke, has been increased in recent years, so it is significant to estimate arterial stiffness for preventing these diseases in clinical. Compared with the global pulse wave velocity (PWV) of the arteries, the regional PWV can provide more accurate elastic properties of the arterial wall, which is helpful for the better diagnosis and the earlier prognosis of the cardiovascular disease. Nowadays, measurement of the regional PWV with tansit time (TT) method based on the ultrasound RF signals for quantitative evaluation of arterial stiffness is a main foucus in current reference research field. However, the researches on the accurate performance, related influence factors and the improvement of method are insufficient.In present study, an ultrasound simulation model for pulse wave propagation along a common carotid artery is proposed and the estimated values and errors calculated from the wall displacements, the delay time of pulse wave transit and the linear-regression-based PWV based on the RF ultrasound signals are analysed quantitatively during the measurement of PWV, and then an investigation on accurate performance of PWV measurement and influence factors, such as beam numbers and frame rate of ultrasound scanning is conducted systemically. The results show that not the frame rates but the delay time affect much of the wall displacements accuracy because the average estimated errors of time shifts increase from0.34ms to1.43ms with the frame rates decreased, and the beam numbers only affects the accurate performance of the linear-regression-based PWV. The two factors finally cause that the estimated PWV of carotid artery based on ultrasound RF signals suffers from errors ranged from7%to65%, but7%to20%when the beam numbers are not less than10with a higher accuracy. Above all, the low frame rates of ultrasound imaging are the main cause in the errors of PWV estimation when the beam numbers are at least10. To solve this problem, an innovative method is presented to increase the temporal resolution of the wall displacements and improve the PWV accuracy. The results show that the errors of the estimated PWV are ranged from11%to13%when the wall displacements of576Hz-.376Hz and226Hz are interpolated to1127Hz respectively, but6.5%to8.5%when the minimum beam numbers are10. What’s more, when the wall displacements of226Hz are interpolated to1500Hz,2000Hz,2500Hz,3000Hz, the average estimated PWV errors only suffers from5%-12%, and5%-7%when beam numbers are at least10. To sum up, the accuracy performance of PWV can be increased largely according to the two interpolating methods and the PWV accuracy is higher as the frame rates of wall displacements are interpolated to1500Hz or more.The research results not only contribute to a better grasp of the error reasons and accurate performance of PWV based on ultrasound RF signals, but also provide reasonable basis for the subsequent enhancement. of PWV estimation method in clinical.