In Vivo 1H NMR Spectroscopy of the Human Brain at High Magnetic Fields: Metabolite Quantification at 4T vs. 7T
In Vivo 1H NMR Spectroscopy of the Human Brain at High Magnetic Fields: Metabolite Quantification at 4T vs. 7T
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DOI：
10.1002/mrm.22086
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发表时间：
2009-10-01
影响因子：
3.3
通讯作者：
Gruetter, Rolf
中科院分区：
文献类型：
--
作者：
Tkac, Ivan;Oz, Gulin;Gruetter, Rolf
在4 T和7 T条件下，使用具有相同控制台、相同类型RF线圈、相同脉冲序列和数据分析的MR扫描仪，对相同的10名受试者进行了一项人脑代谢物定量的综合比较研究。使用半容积正交射频（RF）线圈，在枕叶皮质中选择的感兴趣体积中，7 T相对于4 T的信噪比（SNR）增加了2倍。在7 T下光谱线宽增加了50%，这导致在7 T下的光谱分辨率相对于4 T增加了14%。在两种场强下，对17种脑代谢物进行了可靠的定量。7 T下的代谢物定量对SNR降低的敏感性低于4 T。相对于4 T，7 T下代谢物定量的精密度和弱代表性代谢物的可检测性大幅增加。由于在7 T下增加的光谱分辨率，仅需要4 T光谱的SNR的一半来获得相同的定量精度。在两种场强下，几种代谢物的Cramer-Rao下限（CRLB）（一种定量精密度指标）均低于代谢物浓度的受试者间变异，这导致在4 T和7 T下测量的个体受试者代谢物浓度之间存在强相关性。Magn Reson Med 62：868-879，2009. (C)2009 Wiley-Liss，Inc.
A comprehensive comparative study of metabolite quantification from the human brain was performed on the same 10 subjects at 4T and 7T using MR scanners with identical consoles, the same type of RF coils, and identical pulse sequences and data analysis. Signal-to-noise ratio (SNR) was increased by a factor of 2 at 7T relative to 4T in a volume of interest selected in the occipital cortex using half-volume quadrature radio frequency (RF) coils. Spectral linewidth was increased by 50% at 7T, which resulted in a 14% increase in spectral resolution at 7T relative to 4T. Seventeen brain metabolites were reliably quantified at both field strengths. Metabolite quantification at 7T was less sensitive to reduced SNR than at 4T. The precision of metabolite quantification and detectability of weakly represented metabolites were substantially increased at 7T relative to 4T. Because of the increased spectral resolution at 7T, only one-half of the SNR of a 4T spectrum was required to obtain the same quantification precision. The Cramer-Rao lower bounds (CRLB), a measure of quantification precision, of several metabolites were lower at both field strengths than the intersubject variation in metabolite concentrations, which resulted in a strong correlation between metabolite concentrations of individual subjects measured at 4T and 7T. Magn Reson Med 62: 868-879, 2009. (C) 2009 Wiley-Liss, Inc.