超导量子干涉仪及其在低场核磁共振及成像中的应用

Superconducting Quantum Interference Device and Its Application in Low-Field Nuclear Magnetic Resonance & Imaging

超导量子干涉仪利用约瑟夫森结宏观量子干涉效应,是一种具有超高灵敏度的磁通探测器件。对超导量子干涉仪的基本原理及其在低场核磁共振/成像技术中的应用进行了简要介绍,并报道了在这方面的主要研究成果。搭建了一套低场核磁共振及成像系统并获得具有较高信噪比的水样品1H质子NMR谱及三氟乙醇的纯J-耦合谱,同时还测到了清晰的自旋回波信号。在此基础上,采用直接背投影重建方法,尝试并成功获得了水样品和生物样品的一维及二维核磁共振像。采用8 nm粒径的超顺磁Fe3O4磁性纳米粒子作为对比增强剂,研究了磁性纳米粒子对1H核自旋纵向弛豫时间T1的影响,据此演示了磁性纳米粒子T1加权对比度增强成像实验,所得二维核磁共振像随极化时间的不同显示出显著的对比度变化。

Superconducting Quantum Interference Device （SQUID） is a kind of ultra-sensitive flux detector based on macroscopic quantum interfereneephenomenon of Josephson junctions. The principle of SQUID and advantages of its appli- cation in low-field nuclear magnetic resonance （NMR） ＆imaging （MRI） technologies are introduced, and some important experimental results are reported here. We built a low-field NMR＆MRI system and obtained highly improved 1 H proton FID＆Spin echo spectra. Pure J-coupling spectrum of 2, 2, 2-Trifluoroethyl was also measured and agreed well with high- field NMR results. In addition, we tried and successfully obtained 1D and 2D MRI images of water phantoms and bio-sam- pies. The influence of 8nm Fe304 magnetic nanoparticles on longitudinal relaxation time of water was studied. Based on this property, we illustrated Tl-contrast enhanced 2D imaging of water phantoms by using magnetic nanoparticles, which show evident contrast variation under different pre-polarization times.