High Frame Rate Imaging to Enhance the Dissolution of Histotripsy-Induced Bubble Clouds

Histotripsy is a focused ultrasound therapy for tissue ablation with bubble cloud activity. Persistent bubble clouds reduce the ablative capacity of histotripsy. Thus, there is a need for bubble-specific imaging to track bubble cloud dissolution between the application of histotripsy pulses. In this study, standard plane wave, pulse inversion, and chirp-coded excitation imaging were utilized to visualize bubble clouds at a 2-kHz frame rate. For all imaging schemes, a monotonic decrease in the bubble cloud grayscale was observed over a 45-ms period following the histotripsy insonation. The change in bubble cloud grayscale was dependent on the imaging scheme, with faster grayscale reduction for larger peak negative pressures of the imaging pulse. Bubble-specific sequences resulted in faster decreases in the bubble cloud grayscale compared with standard plane wave imaging. Overall, these results highlight high-frame rate imaging as a means to monitor and modulate histotripsy bubble cloud dissolution.