Closed Loop Spatial and Temporal Control of Cavitation Activity with Passive Acoustic Mapping

Area of Science:

• Biomedical Engineering
• Acoustics
• Medical Physics

Background:

• Ultrasonically triggered microbubble oscillations show potential for minimally invasive therapies.
• Current preclinical studies highlight the need for real-time control over microbubble cavitation for clinical translation.

Purpose of the Study:

• To develop a real-time nonlinear state controller for precise management of microbubble oscillations.
• To achieve spatial and temporal control of cavitation activity using acoustic emissions.

Main Methods:

• Implementation of a controller utilizing passive acoustic mapping (PAM) with frequency-selective analysis.
• Employing the angular spectrum approach for high signal-to-noise ratio mapping.
• Utilizing specific frequency bands (e.g., 3rd harmonic) of microbubble acoustic emissions as observer states.

Main Results:

• The PAM-based controller achieved targeted cavitation control within 6 seconds, maintaining 10% tolerance for 45 seconds.
• Demonstrated spatial selectivity in controlling cavitation when multiple regions were active simultaneously.
• Showcased robustness across various parameters, noise levels, and bubble concentrations.

Conclusions:

• The proposed real-time nonlinear state controller based on PAM offers precise, spatially selective control of microbubble cavitation.
• This technology has significant potential for advancing ultrasound-guided minimally invasive therapeutic interventions.
• Further preclinical and clinical research is recommended to validate its efficacy and safety.