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Published on: October 5, 2018
High intensity focused ultrasound lithotripsy with cavitating microbubbles
Shin Yoshizawa1, Teiichiro Ikeda, Akira Ito
1Department of Electrical and Communication Engineering, Tohoku University, Sendai, Japan.
Medical & Biological Engineering & Computing
|April 11, 2009
Summary
High-intensity focused ultrasound (HIFU) lithotripsy utilizes controlled microbubble cavitation to fragment kidney stones. A novel two-frequency waveform effectively collapses cavitation, optimizing stone erosion and producing small fragments.
Area of Science:
- Medical Ultrasound
- Acoustic Cavitation
- Nephrolithiasis Treatment
Background:
- Microbubbles are of significant interest in medical ultrasound for therapeutic applications.
- Controlling microbubble effects enables novel treatment methods, particularly in lithotripsy.
Purpose of the Study:
- Review works on high-intensity focused ultrasound (HIFU) lithotripsy using cavitating microbubbles.
- Investigate a cavitation detection method to optimize HIFU intensity.
- Present a novel two-frequency waveform for controlled cavitation collapse.
Main Methods:
- Designed a cavitation control (C-C) waveform using high-frequency (1-4 MHz) and low-frequency (500 kHz) ultrasound pulses.
- Utilized high-speed photography to observe cavitation collapse and shock-wave emission.
- Conducted in vitro erosion tests on model and natural kidney stones.
- Examined subharmonic acoustic pressure to optimize HIFU intensity.
Main Results:
- The C-C waveform demonstrated superior erosion rates for model stones compared to single-frequency waves.
- Observed a correlation between subharmonic pressure and stone erosion volume.
- Successfully eroded natural stones, producing fragments predominantly smaller than 1 mm.
Conclusions:
- The C-C waveform effectively controls cloud cavitation collapse for kidney stone fragmentation.
- Subharmonic acoustic pressure can be used to optimize HIFU intensity for lithotripsy.
- This method offers potential for a novel lithotripsy system generating small fragments and localized cavitation.
