Pulse-inversion Doppler-based Phase-compensation Reduces Decorrelation in High-frame Rate Contrast-enhanced Ultrasound

Objective: High-frame-rate (HFR) ultrasonic imaging combined with an ultrasound contrast agent (UCA) can be used to study blood flow patterns using echo-particle image velocimetry (echoPIV). Pulse inversion is a common contrast-specific multipulsing scheme for suppressing tissue clutter in ultrasound images while selectively enhancing nonlinear signals from the UCA. However, in fast flow, the displacement of UCA between pulses leads to phase shifts in the echoes that may result in loss of UCA signal, hindering blood flow tracking with echoPIV. Methods: In the present work, a phase-compensation algorithm is proposed to reduce motion-induced signal loss in HFR contrast-enhanced ultrasound imaging using pulse-inversion Doppler (PID). Results: The PID-based phase-compensation algorithm increased image intensity in the high-velocity regions by up to 6 dB in both in vitro and patient data. Also, after PID-based phase compensation, echoPIV was able to measure 27% higher vector velocities in the patient data. Conclusion: The results reveal the feasibility of PID-based phase compensation for reducing signal loss in fast-flow HFR contrast-enhanced ultrasound and its potential for improving blood flow estimation.