Direct in vivo visualization of intravascular destruction of microbubbles by ultrasound and its local effects on tissue.

BACKGROUND Our aim was to observe ultrasound-induced intravascular microbubble destruction in vivo and to characterize any resultant bioeffects. METHODS AND RESULTS Intravital microscopy was used to visualize the spinotrapezius muscle in 15 rats during ultrasound delivery. Microbubble destruction during ultrasound exposure caused rupture of < or = 7-microm microvessels (mostly capillaries) and the production of nonviable cells in adjacent tissue. The number of microvessels ruptured and cells damaged correlated linearly (P<0.001) with the amount of ultrasound energy delivered. CONCLUSIONS Microbubbles can be destroyed by ultrasound, resulting in a bioeffect that could be used for local drug delivery, angiogenesis, and vascular remodeling, or for tumor destruction.