Encapsulated contrast microbubble radial oscillation associated with postexcitation pressure peaks

Area of Science:

• Acoustics
• Biophysics
• Materials Science

Background:

• Microbubbles are widely used in medical imaging and therapy.
• Understanding microbubble behavior under acoustic pressure is crucial for optimizing applications.
• Encapsulated microbubble oscillations can generate detectable acoustic signals.

Purpose of the Study:

• To assess microbubble oscillations and associated broadband pressure peaks after excitation.
• To compare experimental data with theoretical models for microbubble behavior.
• To identify conditions leading to postexcitation signals in encapsulated microbubbles.

Main Methods:

• Experimental acquisition of microbubble responses using a passive cavitation detector.
• Insonification of albumin-shelled and phospholipid-shelled microbubbles with controlled pressure pulses.
• Simulation of microbubble pressure-time responses using the Marmottant et al. model.

Main Results:

• Postexcitation signals increased broadband noise by 4.2-7.2 dB compared to signals without postexcitation.
• Model predictions of increased broadband noise (4.0-8.9 dB) aligned with experimental observations.
• Simulations indicated postexcitation signals occur when radial oscillation exceeds shell break-up and inertial cavitation thresholds.

Conclusions:

• Encapsulated microbubble oscillations generate broadband noise, particularly when postexcitation signals are present.
• The Marmottant model accurately predicts microbubble behavior and the conditions for postexcitation signals.
• Postexcitation signals are a key indicator of significant microbubble inertial cavitation and shell rupture.