一种载磁微泡的超声/磁共振成像研究  

Research on a dual-mode contrast agent with magnetic microbubbles by ultrasound and MRI

作　　者：钟庆芳[1] 祝新[1] 郭各朴 章东[2] ZHONG Qingfang;ZHU Xin;GUO Gepu;ZHANG Dong(Department of Radiology,Jiangsu Province Hospital of Chinese Medicine,Nanjing 210029,China)

机构地区：[1]江苏省中医院放射科,南京市210029 [2]南京大学声学研究所

出　　处：《临床超声医学杂志》2019年第9期641-645,I0001-I0005,共10页Journal of Clinical Ultrasound in Medicine

基　　金：国家自然科学基金项目(11874216、11674173)

摘　　要：目的制备一种超声/MRI双模态载磁微泡,并通过超声成像和MRI成像探讨载磁量对成像效果的影响。方法利用声振法将超顺磁纳米颗粒(SPIO)装载在微泡包膜上,制备超声/MRI双模态造影剂,并根据SPIO的浓度将样品分成Ⅰ~Ⅳ组(分别为0、19.6μg/ml、114.7μg/ml、292.0μg/ml),通过透射电子显微镜和紫外可见分光光度仪测量微泡基本特征和磁浓度,应用体外超声和体外MRI检测成像效果。结果透射电镜技术证实SPIO粒子成功附着,有较好的分散性,粒径呈正态分布,中心粒径约12 nm。体外超声成像显示除气水的声像图表现为无光团,未检测到回声信号;Ⅰ~Ⅳ组随着微泡浓度的增加,回声显著增强,超声图像表现为光团强度增加。Ⅰ~Ⅳ组微泡的组织对比度分别为(5.89±0.70)dB、(8.97±0.80)dB、(11.04±0.72)dB及(12.84±0.56)dB。体外MRI成像显示,T1模式下,随着微泡中磁性粒子浓度增加,其亮度增加;而在T2模式下,随着微泡中磁性粒子浓度增加,T2弛豫时间减小,亮度变弱;双模态微泡溶液和SPIO纳米粒子水溶液的纵向弛豫率分别为7.23 s^-1·mM^-1和5.43 s^-1·mM^-1,横向弛豫率分别为193.62 s^-1·mM^-1和101.55 s^-1·mM^-1。结论载磁造影剂可以增强超声/MRI成像,可为优化多模态微泡造影剂的制备提供实验指导。Objective To prepare an ultrasound/MRI dual-mode magnetic microbubble,and to evaluate the effect of image function of this super paramagnetic iron oxide nanoparticles(SPIO)with different magnetic concentration by ultrasound and MRI.Methods SPIO were loaded on the microbubble capsule by acoustic vibration method to prepare ultrasound/MRI bimodal contrast agent.According to different SPIO concentration,the samples were grouped asⅠ~Ⅳgroup(corresponding to 0,19.6μg/ml,114.7μg/ml,292.0μg/ml,respectively),the physical characterizations were examined by transmission electron microscopy and UV-visible light absorption spectrum.The effect of image funciton with different SPIO concentration was further investigated by US/MRI.Results The SPIOs were successfully loaded on the albumin microbubbles,and had good dispersibility with a central particle size of 12 nm,confirmed with transmission electron microscopy technology.No hyperechoic region was observed with the degassed water in ultrasound imaging.While hyperechoic regions can be clearly observed in the testing chamber with microbubble,and the higher concentration of SPIO,the higher intensity of echo were observed inⅠ~Ⅳgroups.The contrast-to-tissue ratio were(5.89±0.70)dB,(8.97±0.80)dB,(11.04±0.72)dB and(12.84±0.56)dB in groupⅠ~Ⅳ,respectively.MRI showed that in T1 mode,the brightness of microbubbles increased with the concentration of magnetic particles in microbubbles increased.In T2 mode,with the concentration of magnetic particles in microbubbles increased,T2 relaxation time decreased,and brightness decreased.The longitudinal relaxation rates of bimodal microbubble solution and SPIO nanoparticle solution were 7.23 s^-1·mM^-1 and 5.43 s^-1·mM^-1,and the transverse relaxation rates were 193.62 s^-1·mM^-1 and 101.55 s^-1·mM^-1,respectively.Conclusion Magnetic contrast agent can enhance ultrasound/MRI imaging and provide experimental guidance for optimizing the preparation of multi-mode microbubble contrast agent.

关 键 词：造影剂 多功能 微泡 超顺磁纳米颗粒 超声成像 磁共振成像 

分 类 号：R445.1[医药卫生—影像医学与核医学]