Objective      To investigate the injury of microbubble-enhanced ultrasound cavitation on microvessles in muscle and lung of rabbit.       Methods      Leg muscles and right lungs of 15 New Zealand rabbits were treated for 5 min using a pulsed therapeutic ultrasound device (CZ-960) with intravenous injection of lipid microbubble. The muscles and right lungs of 5 rabbits were harvested for pathological examination immediately after treatment. Contrast enhanced ultrasound (CEUS) was performed before and after the treatment at 0 min

30 min

60 min and 48 h in the rest 10 rabbits. Contrast peak intensity (PI) was quantified to assess the muscle blood perfusion. The muscles and right lungs of 5 rabbits were collected for pathological examination after 48 h of contrast enhancement.       Results      Petechial haemorrhage occurred in gross muscles and lung surfaces immediately after the treatment. No significant CEUS PI difference of muscle was found before and after treatment. We found microvascular rupture in the form of focal hemorrhage and edema in muscle and lung immediately after the treatment. In 48 h later

most focal hemorrhage and edema disappeared and were replaced by minute focal necrosis in muscle.       Conclusion      Microbubble-enhanced ultrasound cavitation can induce regional and limited microvascular hemorrhage in muscle and lung

with no impact on muscular blood perfusion. Therefore

the treatment has little effect on the microvessles in the muscle and lung.