Noninvasive simultaneous measurements of neurotransmitters in human brain using high field MR system

谷氨酸和GABA是人脑中的主要神经递质。提示它们与退行性神经疾病和精神障碍有一定关系。因此，这些代谢物是~1H-MS的重要研究对象之一。然而，由于这些代谢物具有JHH偶联自旋体系，在体内很难检测到它们。由于这种耦合和密切的化学位移，这些峰的特征是复杂的，在临床1.5T磁共振系统中它们严重重叠。即使在目前应用于临床领域的3T，这些困难也没有得到足够的改善。本研究的目的是在活体内同时检测和定量人脑中的谷氨酸和GABA。首先，我们开发了体内谷氨酸和GABA峰值检测的新方法。这些峰可以在人脑4.7T的定位CT COSY谱上分辨出来。其次，发展了ISIS CT COSY方法来改善由于化学位移引起的切片位移误差。该方法还改善了切片轮廓。还开发了后处理方法来改善沿F2轴的失真和沿F1轴的伪影。最后，我们开发了一种使用ISIS CT COSY对活体2D光谱进行定量的方法。该方法包括J&lt；HH&GT；耦合自旋系统的T_2补偿和二维谱峰的曲线拟合。用该方法对人脑中谷氨酸和GABA进行了同时定量，计算出谷氨酸和GABA的浓度分别为11.7 mM和0.95 mM。这些数值都在报告的数值之内。

Glutamate and GABA are major neurotransmitters in human brain. It is suggested that they have some relation with degenerative nerve diseases and psychiatric disorders. Then, these metabolites are one of the important subjects for ^1H MRS.However, it is difficult to detect these metabolites in vivo, because they have JHH coupled spin systems. Due to this coupling and close chemical shifts, the features of these peaks are complicated and they are severely overlapped at clinical 1.5 T MR systems. Even at 3 T which are now applied to clinical fields, these difficulties are not enough improved.The purpose of our studies was to detect and quantify glutamate and GABA in human brain in vivo simultaneously. First, we have developed new measurement methods for peak detection of glutamate and GABA in vivo. These peaks could be resolved on localized CT COSY spectra at 4.7 T in human brain. Next, ISIS CT COSY method has been developed to improve slice displacement error due to chemical shifts. This method also improves slice profile. Post processing methods have also developed to improve distortion along F_2 axis and artifacts along F_1 axis. Finally, we have developed a quantitation method on in vivo 2D spectra using ISIS CT COSY. This method consists of T_2 compensation of J_<HH> coupled spin systems and curve fitting of peak on 2D spectra. By this method, we have quantified glutamate and GABA simultaneously in human brain and these concentrations were calculated as 11.7 mM and 0.95 mM respectively. These values were within reported values.