Optimum Parameters in Ultrasound Coherent Plane Wave Compounding for High LPWV Estimation

Objectives-The aim of this study is to determine the optimum and fine values of the number and transmission angles of tilted plane waves for coherent plane-wave compounding (CPWC)-based high local pulse wave velocity (LPWV) estimation. Methods-A Verasonics system incorporating a linear array probe L14-5/38 with 128 elements and a pulsatile pump, CompuFlow1000, were used to acquire radio frequency data of 3, 5, 7, and 9 tilted plane wave sequences with angle intervals from 0 degrees to 12 degrees with a coarse interval increment step of 1 degrees, and the angle intervals from 0 degrees to 2 degrees with a fine interval increment step of 0.25 degrees from a carotid vessel phantom with the LPWV of 13.42 +/- 0.90 m/s. The mean value, standard deviation, and coefficients of variation (CV) of the estimated LPWVs were calculated to quantitatively assess the performance of different configurations for CPWC-based LPWV estimation. Ten healthy human subjects of two age groups were recruited to assess the in vivo feasibility of the optimum parameter values. Results-The CPWC technique with three plane waves (PRF of 12 kHz corresponding to a frame rate of 4000 Hz) with an interval of 0.75 degrees had LPWVs of 13.52 +/- 0.08 m/s with the lowest CV of 1.84% on the phantom, and 5.49 +/- 1.46 m/s with the lowest CV of 12.35% on 10 subjects. Conclusions-The optimum parameters determined in this study show the best repeatability of the LPWV measurements with a vessel phantom and 10 healthy subjects, which support further studies on larger datasets for potential applications.