不同流速条件下磁性微泡溶液的聚焦超声温升效应
The temperature enhancement effect of magnetic microbubble agents induced by focused ultrasound exposures under different flow rate conditions
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摘要: 为深入理解血液等流动液体环境中高强度聚焦超声(HIFU)引发的磁性微泡溶液的温升效应的变化规律, 本研究制备了可同时用作超声和磁共振成像造影剂的双模态磁性微泡, 测量了挂载不同浓度的超顺磁性氧化 (SPIO) 纳米颗粒的双模态磁性微泡溶液的声衰减系数, 并制备凝胶仿体, 采用测温针测量不同流速条件下的经超声辐照的双模态磁性微泡增强HIFU热效应的能力, 最后采用有限元方法对实验环境进行仿真, 并与实验结果对比。结果显示, 相比传统的蛋白微泡, 磁性微泡溶液的声衰系数及比热容更高, 增加微泡包膜中 SPIO 纳米颗粒挂载浓度可引起更快的温度抬升, 达到更高的局部峰值温度。溶液流速对磁性微泡溶液中温度变化的影响较为复杂, 总体而言, 液体的流动会削弱微泡溶液在超声辐照下的温度累积效果。Abstract: To further understand the changes in temperature enhancement effects induced by high-intensity focused ultrasound (HIFU) in fluid environments such as blood, this study prepared dual-modal magnetic microbubbles that can be used as contrast agents for both ultrasound and magnetic resonance imaging. The study measured the acoustic attenuation coefficient of dual-modal magnetic microbubble solutions loaded with different concentrations of superparamagnetic iron oxide (SPIO) nanoparticles. Gel phantoms were prepared, and the ability of microbubbles to enhance HIFU thermal effects under different flow rates were measured using temperature probes after ultrasound irradiation. Finally, finite element method was conducted to simulate the experimental environment and compared with experimental results. The results showed that compared to traditional protein microbubbles, magnetic microbubble solutions exhibited higher acoustic attenuation coefficients and specific heat capacities. Increasing the concentration of SPIO nanoparticles mounted on the microbubble membrane led to faster temperature elevation and higher peak temperatures locally. The effect of solution flow rate on temperature changes in magnetic microbubble solutions was complex; generally, fluid flow weakened the temperature accumulation effect of the microbubble solution under ultrasound irradiation.