7.0 T MR γ-氨基丁酸化学交换饱和转移成像的新技术研究  

Study of a new method for imaging of GABA based on chemical exchange saturation transfer using a 7.0 T MR scanner

作　　者：章桃 贾岩龙[1] 聂婷婷[1] 易美芝[1] 戴卓智[1] 延根[1] 吴仁华[1,2] 

机构地区：[1]汕头大学医学院第二附属医院放射科,汕头515041 [2]广东省医学影像实验教学示范中心,汕头515041

出　　处：《磁共振成像》2015年第5期385-389,共5页Chinese Journal of Magnetic Resonance Imaging

基　　金：国家自然科学基金重点项目(编号:30930027)

摘　　要：目的γ-氨基丁酸是大脑内最主要的抑制性神经递质,作者运用一种基于化学交换饱和转移(CEST)的MRI新方法对γ-氨基丁酸进行成像。材料与方法实验在安捷伦7.0 T动物MR扫描仪上完成,配制不同浓度γ-氨基丁酸及其他代谢物溶液(谷氨酸、肌醇、肌酸及胆碱)的试管模型,在温度与酸碱度统一的情况下,分别获得γ-氨基丁酸及其他代谢物Z谱图,并通过收集CEST图研究γ-氨基丁酸的CEST效应与浓度的关系及其他代谢物对γ-氨基丁酸CEST效应的潜在贡献。结果通过谱线分析,在偏离水峰2.75 ppm处可以明显地观察到γ-氨基丁酸的CEST效应。改变B1值后获得的Z谱非对称曲线显示γ-氨基丁酸的CEST效应随着B1值的增大而增加,在6.0μT(255 Hz)下达到最大值。体外试管CEST成像显示γ-氨基丁酸的图像信号随其浓度升高而升高,在2.75 ppm处获得的大脑中其他代谢物CEST图示除谷氨酸外其他代谢物几乎不显影。结论实现了γ-氨基丁酸的特异性成像,在本实验条件下获得了最优预饱和能量B1值为6μT,提供了一种无创、无放射性及高时空分辨率的成像方法,有望获得在体的γ-氨基丁酸浓度分布结构图。Objective： γ-aminobutyric acid （GABA） is an important inhibitory neurotransmitter in the brain. In this study, we developed a novel MRI technique to measure GABA based on chemical exchange saturation transfer （CEST）.Materials and Methods：All the MRI studies were performed in a 7.0 T Agilent MRI scanner. Z-spectra of GABA and other metabolites （glutamate, myo-inositol, creatine and choline） were acquired at 37°and pH 7.0, respectively. CEST images of phantoms with different concentrations of GABA solutions and other metabolites were collected to investigate the concentration dependent CEST effect of GABA and the potential contributions from other brain metabolites.Results：The CEST effect of GABA was observed at 2.75 ppm downifeld from bulk water. The CEST effect of GABA increased with B1 amplitude and kept steady after the B1 reached 6.0 μT. The CEST effect of GABA was proportional to the GABA concentration in vitro. Except for a small contribution from glutamate, all other metabolites contributed negligible CEST effects to GABACEST at 2.75 ppm.Conclusions： These ifndings demonstrate the feasibility and potential to map changes in GABA concentration using CEST with a optimal B1 amplitude, which has excellent spatial and temporal resolution.

关 键 词：Γ-氨基丁酸 磁共振成像 代谢 

分 类 号：R445.2[医药卫生—影像医学与核医学]