脉冲占空比对磁性微泡介导的聚焦超声温升效应的影响  

Effect of pulse duty ratio on temperature rise induced by focused ultrasound combined with magnetic microbubbles

作　　者：张玫玫 吴意赟[1,2] 于洁 屠娟[1] 章东[1] Zhang Mei-Mei;Wu Yi-Yun;Yu Jie;Tu Juan;Zhang Dong(Key Laboratory of Modern Acoustics of the Ministry of Education,Department of Physics,Nanjing University,Nanjing 210093,China;Department of Ultrasound Medicine,Affiliated Hospital of Nanjing University of Chinese Medicine,Nanjing 210029,China)

机构地区：[1]南京大学物理学院,近代声学教育部重点实验室,南京210093 [2]南京中医药大学附属医院,南京210029

出　　处：《物理学报》2023年第8期196-203,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12227808,12274220,52100014,11874216,11934009,11911530173);声场声信息国家重点实验室开放课题(批准号:SKLA202212,SKLA202107);南通南京大学材料工程技术研究院基础科学研究计划(批准号:JCA41-01)资助的课题.

摘　　要：集合多种诊断和治疗功能的声/磁造影剂微泡的研究与开发已经成为当前医学超声、生物医学工程及临床应用领域共同关注的热点问题.超顺磁氧化铁纳米颗粒具有独特的磁性特征和良好的生物相容性,可被用作核磁共振造影剂来提升影像对比度、空间分辨率及临床诊断准确性.我们的前期工作表明,通过将超顺磁氧化铁纳米颗粒挂载于常规超声造影剂微泡表面,可以成功构建多模态诊断及治疗介质,显著改变超声造影剂微泡的尺度分布及包膜粘弹系数等物理特性,进而影响微泡造影剂的声散射特性及其声空化效应和热效应.然而,此前的研究仅考虑了声场强度和微泡浓度等影响因素,对于脉冲超声时间特性对磁性微泡造影剂动力学响应的影响的相关研究仍有所欠缺.本文通过热电偶对凝胶仿体血管模型中流动的双模态磁性微泡在不同占空比超声脉冲信号作用下,产生温升效应开展了系统的实验测量,并基于有限元模型对实验结果进行了仿真验证.结果显示,脉冲信号占空比的提升是增强血管中磁性微泡在聚焦超声作用下温升效果的关键性时间影响因素.本文的研究成果将有助于更好地理解不同超声作用参数对双模态磁性微泡的热效应的影响机制,对保障双模态磁性微泡在临床热疗应用中的安全性和有效性具有重要的指导意义.Development of acoustic/magnetic contrast agent microbubbles with various diagnostic and therapeutic functions has attracted more and more attention in medical ultrasound,biomedical engineering and clinical applications.Superparamagnetic iron oxide nanoparticles(SPIO)have unique magnetic characteristics and wonderful biocompatibility,so they can be used as MRI contrast agents to improve image contrast,spatial resolution and diagnostic accuracy.Our previous work shows that the multimodal diagnostic and therapeutic microbubble agents can be successfully constructed by embedding SPIO particles into the coating shell of conventional ultrasound contrast agent(UCA)microbubbles,which in turn changes the size distribution and shell properties of UCA microbubbles,thereby affecting their acoustic scattering,cavitation and thermal effects.However,previous studies only considered the influence factors such as acoustic pressure and microbubble concentration.The relevant investigation regarding the influence of ultrasound temporal characteristics on the dynamic response of magnetic microbubbles is still lacking.This work systematically measures the temperature enhancement effect of the SPIO-albumin microbubble solution flowing in the vascular gel phantom exposed to pulsed ultrasound with various temporal settings(e.g.duty cycle,PRF and single pulse length).Meanwhile,a two-dimensional finite element model is developed to simulate and verify the experimental observations.The results show that the increase of duty cycle of pulse signal should be the crucial factor affecting the temperature enhancement effect of flowing SPIO-albumin microbubble solution under the exposure to high-intensity focused ultrasound.The current results help us to better understand the influence of different acoustic setting parameters on the thermal effect of dual-modal magnetic UCA microbubbles,and provide useful guidance for ensuring the safety and effectiveness of the application of SPIO-albumin microbubbles in clinics.

关 键 词：超顺磁氧化铁纳米颗粒 聚焦超声 热效应 占空比 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]