High frame rate ultrasound imaging of vaporised phase change contrast agents

Phase-change ultrasound contrast agents (PCCAs), have shown promises for ultrasound-mediated diagnostics and therapeutics. High-frame-rate ultrasound imaging with microbubbles significantly improved temporal resolution and contrast compared to conventional contrast-enhanced ultrasound imaging, offering opportunities to observe and better understand PCCA behavior after vaporisation. In this study, high-frame-rate ultrasound was used to image the PCCAs immediately after vaporisation in vitro with clinical ultrasound parameters. Compared with microbubbles, the vaporised PCCAs have shown different temporal signal features with high-frame-rate ultrasound imaging: a significant decrease in the first tens of milliseconds after acoustic vaporisation while no evident change over time with microbubble signal. Simultaneous optical microscopy was operated to observe behaviors of the vaporised PCCAs. Highframe-rate ultrasound imaging enables improved understanding of the acoustic behavior of the vaporised PCCA populations at high temporary resolution.