Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Magn Reson Med. 2009 Oct;62(4):862-7. doi: 10.1002/mrm.22022.
Knowledge of T(1) relaxation times can be important for accurate relative and absolute quantification of brain metabolites, for sensitivity optimizations, for characterizing molecular dynamics, and for studying changes induced by various pathological conditions. (1)H T(1) relaxation times of a series of brain metabolites, including J-coupled ones, were determined using a progressive saturation (PS) technique that was validated with an adiabatic inversion-recovery (IR) method. The (1)H T(1) relaxation times of 16 functional groups of the neurochemical profile were measured at 14.1T and 9.4T. Overall, the T(1) relaxation times found at 14.1T were, within the experimental error, identical to those at 9.4T. The T(1)s of some coupled spin resonances of the neurochemical profile were measured for the first time (e.g., those of gamma-aminobutyrate [GABA], aspartate [Asp], alanine [Ala], phosphoethanolamine [PE], glutathione [GSH], N-acetylaspartylglutamate [NAAG], and glutamine [Gln]). Our results suggest that T(1) does not increase substantially beyond 9.4T. Furthermore, the similarity of T(1) among the metabolites (approximately 1.5 s) suggests that T(1) relaxation time corrections for metabolite quantification are likely to be similar when using rapid pulsing conditions. We therefore conclude that the putative T(1) increase of metabolites has a minimal impact on sensitivity when increasing B(0) beyond 9.4T.
T1 弛豫时间的知识对于脑代谢物的准确相对和绝对定量、灵敏度优化、分子动力学特征描述以及研究各种病理条件引起的变化非常重要。（1）H T1 弛豫时间使用逐步饱和（PS）技术确定，该技术使用绝热反转恢复（IR）方法进行验证。在 14.1T 和 9.4T 下测量了神经化学特征的 16 个功能组的（1）H T1 弛豫时间。总体而言，在实验误差范围内，14.1T 下测量的 T1 弛豫时间与 9.4T 下的弛豫时间相同。神经化学特征的一些偶联自旋共振的 T1 首次被测量（例如 GABA、Asp、Ala、PE、GSH、NAAG 和 Gln 的 T1）。我们的结果表明，T1 不会在 9.4T 以上大幅增加。此外，代谢物之间 T1 的相似性（约 1.5s）表明，在使用快速脉冲条件时，代谢物定量的 T1 弛豫时间校正可能相似。因此，我们得出结论，当 B0 增加到 9.4T 以上时，代谢物的假定 T1 增加对灵敏度的影响最小。
