Measurement of local pulse wave velocity using fast ultrasound imaging

Abstract

Carotid to femoral pulse wave velocity (cfPWV) is considered as the gold standard of arterial stiffness. We hypothesize that local pulse wave velocity (LPWV) may be a close surrogate of the cfPWV. Current method of measuring cfPWV is intrusive, inconvenient and requires manual measurement of carotid-femoral distance. While other measures of arterial stiffness can be done using ultrasound imaging, cfPWV required separate specialized equipment. In this paper, we provide a proof of concept of possibility of measuring LPWV on fast ultrasound frames. We used Verasonics® Vantage-256 Research ultrasound system to obtain longitudinal carotid frames at a frame rate of more than 750 frames per second. Diameter waveforms are obtained from two ends of these longitudinal frames. The minute time shift between these waveforms is used to calculate the time of flight of the waveform from one end of the carotid to other. The known distance between pixels on beamformed frames are used to calculate the LPWV. Measurements for five human volunteers were obtained which were found to statistically equal to the cfPWV measured using SphygmoCor.