A new active cavitation mapping technique for pulsed HIFU applications--bubble Doppler

Area of Science:

• Ultrasound physics
• Biomedical engineering
• Acoustic cavitation

Background:

• Pulsed high-intensity focused ultrasound (pHIFU) utilizes transient cavitation bubbles to enhance drug and gene delivery.
• Current methods like passive cavitation detection (PCD) and B-mode imaging have limitations in spatial resolution and sensitivity to microbubbles.
• Accurate monitoring of cavitation is crucial for optimizing pHIFU therapies.

Purpose of the Study:

• To propose and test a new active cavitation mapping technique, bubble Doppler, for pHIFU applications.
• To evaluate the feasibility of bubble Doppler in tissue-mimicking phantoms.
• To overcome the limitations of existing cavitation detection methods.

Main Methods:

• Developed bubble Doppler by fusing adaptations of color Doppler, pulse-inversion Doppler, and decorrelation Doppler techniques.
• Interleaved Doppler ensemble pulses with therapeutic pHIFU pulses using three pulse sequences.
• Applied standard Doppler processing to received echoes for cavitation bubble analysis.

Main Results:

• Evaluated the complementary information provided by individual Doppler techniques on cavitation bubble distribution and characteristics.
• Demonstrated the feasibility of the bubble Doppler technique in tissue-mimicking gel phantoms.
• Showcased the ability of bubble Doppler to spatially map transient bubbles and estimate their sizes and nonlinearity.

Conclusions:

• Bubble Doppler is a feasible active cavitation mapping technique for pHIFU applications.
• This unified approach provides complementary information for spatial mapping and characterization of cavitation bubbles.
• Bubble Doppler offers improved visualization and monitoring capabilities for pHIFU-guided therapies.