Mice were injected with 0.1 mt Albunex(R) and exposed to 200 pulses from a piezoelectric lithotripter at times ranging from 5 min to 24 h following injection. Each pulse was approximately 1.5 sinusoidal oscillations at a fundamental frequency of similar to 0.1 MHz with pressure amplitude of similar to 2 MPa, Although the contrast agent ceases to be an effective scatterer of diagnostic ultrasound after a few minutes in the circulation, the modest lithotripter exposures caused significant hemorrhaging in bladder, mesentery and intestine for periods of up to 4 h after injection, The results demonstrate either that highly stable bubbles much smaller than resonance size or air-containing fragments of the shells of Albunex(R) serve as effective nuclei for acoustic cavitation. (C) 1997 World Federation for Ultrasound in Medicine & Biology.
