Simultaneous Tissue and Flow Estimation at High Frame Rate Using Plane Wave and Transverse Oscillation on in Vivo Carotid

In this study, a method to estimate tissue motion and vector flow fields, from a unique ultrasound plane wave sequence, was applied to several in vivo carotid data sets. Moreover, pulse wave velocity was also extracted thanks to the wall velocity estimates. Acquisitions were performed at high frame rate using horizontal plane waves without compounding (5 000 Hz). Results showed that the method could simultaneously yield wall velocity and flow in case of low or high flow rates and even when complex patterns occur. Moreover, pulse wave velocities were estimated from two distinct waves; one is measured from the foot of displacement (forward wave) while the second one is extracted at the dicrotic notch. The forward wave has been estimated with a value of 3.25 ± 0.81 m/s while the second one has been measured at 5.43 ± 1.30 m/s; the difference can be explained with the two different pre-loads on the artery wall. Overall, the method can simultaneously extract fast and complex phenomena that can occur in both tissue and flow. Thanks to the simultaneous assessment of those characteristics, new pathological indicators could be discovered by studying the relationship and synchronization between flow and wall motion.