Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA.
Magn Reson Med. 2018 Mar;79(3):1260-1265. doi: 10.1002/mrm.26826. Epub 2017 Jul 10.
The goal of this study was to measure and compare the apparent transverse relaxation time constants (T ) of five intracellular metabolites using localization by adiabatic selective refocusing (LASER) and point-resolved spectroscopy (PRESS) sequences in the human brain at 3 T.
Five healthy subjects were studied at 3 T. H spectra from the prefrontal cortex were acquired at six different echo times using LASER and PRESS sequences. Postprocessed data were analyzed with LCModel, and the resulting amplitudes were fitted using a mono-exponential decay function to determine the T of metabolites.
Twenty-one percent higher apparent T values for the singlet resonances of N-acetyl aspartate, total creatine, and total choline were measured with LASER as compared with PRESS, whereas comparable apparent T values were measured for strongly coupled metabolites, glutamate, and myo-inositol, with both sequences.
Reliable T measurements were obtained with both sequences for the five major intracellular metabolites. The LASER sequence appears to be more efficient in suppressing the diffusion component for singlets (having nonexchangeable protons) compared to J-coupled metabolites. Magn Reson Med 79:1260-1265, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
本研究旨在测量并比较 5 种细胞内代谢物在 3T 人脑应用绝热选择性激励（LASER）和点分辨波谱（PRESS）序列的表观横向弛豫时间常数（T ）。
本研究纳入了 5 名健康志愿者，在 3T 下进行研究。应用 LASER 和 PRESS 序列，在 6 个不同回波时间点采集前额叶皮质的 H 波谱。使用 LCModel 对后处理数据进行分析，应用单指数衰减函数对得到的振幅进行拟合，以确定代谢物的 T 值。
与 PRESS 序列相比，LASER 序列测量到的 N-乙酰天冬氨酸、总肌酸和总胆碱的单峰共振的表观 T 值高 21%，而谷氨酸和肌醇这两种强耦合代谢物的表观 T 值与两种序列相当。
两种序列均能可靠地测量 5 种主要细胞内代谢物的 T 值。与 J 耦合代谢物相比，LASER 序列在抑制单峰（具有不可交换质子）的扩散分量方面似乎更有效。磁共振医学 79：1260-1265，2018。© 2017 国际磁共振学会。
