低频超声场中微血管内微泡动力学仿真研究

Dynamic study of microbubble in microvessel at low frequency ultrasound field

在低频超声激励下,研究超声微泡的非线性声学响应,及其与周围生理环境之间的关系,对微泡定量成像、微血管早期病变检测及微泡靶向治疗等有重要的意义。基于集中参数模型,在COMSOL Multiphysics 4.4中构建激励超声、微泡与血管这三者间的耦合模型并进行仿真计算,结果表明:(1)激励超声声压增大时,微泡振动幅度增加、振动频率减小。(2)血管长度增长时,微泡振幅减小、振频增加;血管内径增大时,微泡振幅增加、振频减小。(3)微泡气体多方指数增加时,血管壁应力、血管形变程度及微泡最大振动速度减小、微泡振动频率增大。(4)血液动力粘度增加时,微泡振动幅度、振动频率、血管壁应力及微泡最大振动速度均减小。

Under the low frequency ultrasound excitation, exploring the nonlinear acoustic response of ultrasound microbubble and its relation to the surrounding physiological environment is significant for the microbubble quantitative imaging, the early detection of microvessel lesions and microbubble targeted therapy. Based on the lumped-parameter model, the coupling model of excitation ultrasound, microbubble and microvessel was constructed, and the simulation calculation was performed in COMSOL Multiphysics 4.4. The results showed that：（1） with the increase of ultrasound pressure, the microbubble oscillation amplitude increased and oscillation frequency decreased;（2） the microbubble oscillation amplitude decreased and oscillation frequency increased with the increase of microvessel length, however, the microbubble oscillation amplitude increased and oscillation frequency decreased with the increase of microvessel radius;（3） with the increase of gas polytropic index, the vessel wall stress, vessel deformation degree and microbubble maximum vibration velocity decreased, while microbubble vibration frequency increased;（4） with the increase of dynamic viscosity of blood, microbubble oscilation amplitude,frequency, maximal oscilation velocity and vessel wall stress reduced.