Comparison of high intensity focused ultrasound enhanced effect of nanobubbles and microbubbles in fresh bovine liver in vitro

Objective To investigate the difference in high intensity focused ultrasound enhanced effect of nanobubbles and microbubbles.Methods The nanobubbles were prepared using mechanical oscillation and low speed centrifugation method.The degassed bovine livers in vitro were respectively injected into 0.2 ml,0.5 ml and 0.8 ml of nanobubbles,microbubbles and PBS when HIFU exposure.HIFU ablation parameters were the following:acoustic power was 180 W,exposure duration was 5 s.After HIFU ablation,the volumes of coagulative necrosis were calculated and recorded.The data were analyzed using statistic method.Results The volumes of coagulative necrosis in bovine liver irradiated by HIFU after local injection of nanobubbles and microbubbles were larger than those of PBS using the same dose(P ﹤ 0.05).With dose increasement of nanobubbles and microbubbles,the volumes of coagulative necrosis increased,but the volumes of coagulative necrosis in different PBS groups were no significant differences(P﹥0.05).Moreover,the volumes of cougulative necrosis of nanobubbles were larger than those of microbubbles with the same dose(P﹤0.05).Conclusion The effect of HIFU ablation was distinctly enhanced with the use of nanobubbles and microbubbles.With the same dose,nanobubbles may be more efficient than microbubbles in HIFU therapy.