Real-time monitoring of pulsed cavitational ultrasound therapy using coherent passive cavitation imaging: perspectives for volumetric imaging

Abstract

Pulsed cavitation ultrasound therapies (PCUT) such as histotripsy are non-invasive therapeutic approaches effective in various medical indications, relying on the mechanical effects generated by inertial cavitation bubbles. Even though limited by the poor contrast, conventional ultrasound B-Mode imaging has been widely used for the guidance and monitoring of the therapeutic procedure, allowing the visualization of the cavitation bubble cloud. However, B-Mode imaging lacks specificity and the visualization of the bubble cloud is often limited in deep and moving organs such as the liver and the heart and remains moreover subjective for the operator. We previously developed a new imaging modality to better identify the cavitation cloud based on a coherent passive ultrasound imaging approach combined with a spatiotemporal filter to map the bubble cloud with high sensitivity and high contrast. Yet, 2D imaging is limited as the therapeutic focal spot is constrained to be located inside the imaging plane, which is an engineering challenge as there might be mechanical misalignments between both the therapy and the imaging transducers as well as ultrasound aberrations leading to monitoring failure. We propose to extend the technique to volumetric imaging, allowing to overcome these limitations, and to explore its performances on an aberrated beam.