Department of Radiology, University of Lausanne, Lausanne, Switzerland.
Magn Reson Med. 2013 Apr;69(4):931-6. doi: 10.1002/mrm.24352. Epub 2012 May 30.
Proton T1 relaxation times of metabolites in the human brain have not previously been published at 7 T. In this study, T1 values of CH3 and CH2 group of N-acetylaspartate and total creatine as well as nine other brain metabolites were measured in occipital white matter and gray matter at 7 T using an inversion-recovery technique combined with a newly implemented semi-adiabatic spin-echo full-intensity acquired localized spectroscopy sequence (echo time = 12 ms). The mean T1 values of metabolites in occipital white matter and gray matter ranged from 0.9 to 2.2 s. Among them, the T1 of glutathione, scyllo-inositol, taurine, phosphorylethanolamine, and N-acetylaspartylglutamate were determined for the first time in the human brain. Significant differences in T1 between white matter and gray matter were found for water (-28%), total choline (-14%), N-acetylaspartylglutamate (-29%), N-acetylaspartate (+4%), and glutamate (+8%). An increasing trend in T1 was observed when compared with previously reported values of N-acetylaspartate (CH3 ), total creatine (CH3 ), and total choline at 3 T. However, for N-acetylaspartate (CH3 ), total creatine, and total choline, no substantial differences compared to previously reported values at 9.4 T were discernible. The T1 values reported here will be useful for the quantification of metabolites and signal-to-noise optimization in human brain at 7 T.
此前尚未在 7T 下公布过人类大脑代谢物的质子 T1 弛豫时间。在这项研究中，我们使用反转恢复技术结合新实现的半绝热自旋回波全强度获取局部光谱序列（回波时间=12ms），在 7T 下测量了枕叶白质和灰质中 N-乙酰天门冬氨酸的 CH3 和 CH2 基团以及总肌酸以及其他 9 种脑代谢物的 T1 值。代谢物在枕叶白质和灰质中的平均 T1 值范围为 0.9 至 2.2 秒。其中，谷胱甘肽、肌醇、牛磺酸、磷酸乙醇胺和 N-乙酰天冬氨酰谷氨酸的 T1 是首次在人脑内确定的。白质和灰质之间 T1 存在显著差异，差异程度为水（-28%）、总胆碱（-14%）、N-乙酰天冬氨酰谷氨酸（-29%）、N-乙酰天门冬氨酸（+4%）和谷氨酸（+8%）。与 3T 下报道的 N-乙酰天门冬氨酸（CH3）、总肌酸（CH3）和总胆碱的先前报道值相比，T1 值呈上升趋势。然而，对于 N-乙酰天门冬氨酸（CH3）、总肌酸和总胆碱，与 9.4T 下的先前报道值相比，没有明显的差异。这里报道的 T1 值将有助于在 7T 下对代谢物进行定量和优化信号噪声比。
