In vivo comparison of multiple pulse and CW strategies for microbubble-enhanced ultrasound therapy

Stabilized microbubble (ultrasound contrast agent) introduction can effectively reduce the propagated energy required to produce tissue damage in vivo. Acoustic parameter adjustment can also produce therapeutic gains. We found that exposures containing multiple, short duration pulses produced more tissue damage than single, CW exposures of the same amplitude and propagated energy, both with and without contrast agent. We suspect the increased tissue damage resulted from the initiation of cavitation and maintenance of a highly dynamic microbubble population during insonation. Results suggest that active adjustment of acoustic parameters may make cavitation more controllable.