Variability of metabolite yield using STEAM or PRESS sequences in vivo at 3.0 T, illustrated with myo-inositol
Variability of metabolite yield using STEAM or PRESS sequences in vivo at 3.0 T, illustrated with myo-inositol
复制标题
DOI：
10.1002/mrm.20434
复制
发表时间：
2005-04-01
影响因子：
3.3
通讯作者：
Allen, PS
中科院分区：
文献类型：
--
作者：
Kim, H;Thompson, RB;Allen, PS
使用作为一个例子，肌醇（毫升）带在类似于3.6 ppm的质子谱从大脑，评估，突出了量化代谢物的困难与强耦合自旋与蒸汽或PRESS，并展示了一些优势的前瞻性序列分析时，测量其浓度。该分析强调耦合自旋信号产率和线型的变化，与非耦合单线态，如N-乙酰天冬氨酸，一个不同的变化，从一个代谢物的自旋系统到另一个。靶代谢物（例如，ml）及其污染背景代谢物（例如，谷氨酸盐和牛磺酸等）在某些情况下，可以大幅减少背景污染（代谢物和大分子），同时保持足够的信噪比以进行精确量化。例如，对于STEAM和PRESS，证明了序列时间，相对于文献中典型的短回波时间序列，分别将ml的3.6-ppm带的代谢物背景的信号增强1.7和1.3倍，基本上消除了大分子基线，并且在两种情况下仍在体内保持类似于10的S/N。Magn Reson Med 53：760-769，2005. (c)2005 Wiley-Liss，Inc.
Using as an example the myo-inositol (ml) band at similar to 3.6 ppm in the proton spectrum from brain, an evaluation is presented that highlights the difficulties of quantifying metabolites with strongly coupled spins with either STEAM or PRESS and demonstrates some advantages of prospective sequence analysis when measuring their concentrations. The analysis emphasizes the variation in coupled-spin signal yield and lineshape, compared with that of uncoupled singlets such as N-acetylaspartate, a variation that differs from one metabolite spin system to another. This difference in variation between a target metabolite (e.g., ml) and its contaminating background metabolites (e.g., glutamate and taurine, etc.) is shown to provide in certain circumstances a substantial reduction in background contamination (both metabolite and macromolecule) while maintaining sufficient signal-to-noise ratio for precise quantification. For example, sequence times are demonstrated, both for STEAM and for PRESS, that, relative to the short echo-time sequences typical in the literature, enhance the signal to metabolite background of the 3.6-ppm band of ml by factors of 1.7 and 1.3, respectively, essentially eliminate the macromolecular baseline, and yet in vivo retain an S/N similar to 10 in both cases. Magn Reson Med 53:760-769, 2005. (c) 2005 Wiley-Liss, Inc.