Multiangle PW Compounding Supports ARFI Variance of Acceleration (VoA) Carotid Plaque Imaging for Integration with Vector Doppler

Acoustic Radiation Force Impulse (ARFI) Log Variance of Acceleration (log(VoA)) was previously demonstrated with a single ARFI excitation and plane wave (PW) tracking to detect plaque structure and composition. However, a separate multi-angle sequence was required to enable simultaneous display of 2-D vector-Doppler (VD) and plaque morphology. This paper evaluates the performance of various multi-angle compounded PW implementations of log(VOA). Experiments were conducted in a CIRS elastic phantom and in an excised human cadaveric carotid. In phantoms, increasing SNR by way of compounding increased inclusion SNR and CNR. Increasing the angle range over which PWs were steered decreased SNR, but did not appreciably change CNR. When applied to the ex vivo carotid, an angle range of 10° best predicted calcium area (as validated by spatially-aligned, expert-segmented histology), and higher number of angles spanning 10° improved delineation of plaque boundaries. These results suggest that, compared to an unsteered PW sequence, a multi-angle compounded PW sequence improves log(VoA) performance, suggesting the potential for extension to implementation with concurrent vector Doppler imaging.