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Correspondence - Nonlinear oscillations of deflating bubbles
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
|December 11, 2012
Summary
Ultrasound contrast microbubbles deflate irreversibly in discrete steps during prolonged ultrasound exposure. This process involves changes in bubble dynamics and may result from gas diffusion and shell material loss.
Area of Science:
- Biomedical Engineering
- Acoustic Physics
Background:
- Phospholipid-coated microbubbles are used as ultrasound contrast agents.
- Ultrasound-induced oscillations can cause microbubble instability, leading to deflation or collapse.
- Understanding microbubble behavior under prolonged ultrasound is crucial for optimizing their use.
Discussion:
- This study examines isolated microbubble dynamics under sustained, low mechanical index ultrasound excitation using ultra-high-speed imaging.
- Observed irreversible deflation occurs in discrete steps, altering bubble oscillation patterns.
- Both symmetric and asymmetric oscillations, including compression-only and expansion-only behaviors, were documented during deflation.
Key Insights:
- Microbubbles exhibit irreversible, non-destructive deflation in stages under prolonged ultrasound.
- Deflation dynamics are characterized by evolving radial oscillations (symmetric and asymmetric).
- Hypothesized mechanisms for deflation include diffusive gas loss and lipid shell material shedding.
Outlook:
- Further research can elucidate the precise mechanisms of gas diffusion and lipid shedding.
- This understanding may lead to the design of more stable ultrasound contrast agents.
- Investigating the impact of different ultrasound parameters on deflation dynamics is warranted.
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