Effect of signal-to-noise ratio and spectral linewidth on metabolite quantification at 4 T
Effect of signal-to-noise ratio and spectral linewidth on metabolite quantification at 4 T
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DOI：
10.1002/nbm.1122
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发表时间：
2007-08-01
影响因子：
2.9
通讯作者：
Bartha, Robert
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文献类型：
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作者：
Bartha, Robert
从短回波时间光谱测量代谢物浓度的准确性和精密度以前被表征为1.5T作为信噪比(SNR)和峰值线宽的函数。本研究的目的是在4T的短回波时间H-1-MR谱中表征与感兴趣的主要代谢物的线宽和信噪比相关的代谢物浓度量化的系统误差。模拟的4T激光局域谱(TE=46ms)在4-14赫兹范围内具有半高宽(FWHM)，在5-500范围内通过在SNR和线宽的每个组合上添加100个高斯分布的噪声实现来产生SNR。线宽和信噪比被视为独立的参数，因此，在信噪比不变的情况下，线宽的增加会导致代谢物面积的增加。使用相同的先验知识和相关参数起始值在时间域中对所有光谱进行拟合。对6种代谢物(N-乙酰天冬氨酸、谷氨酸、肌酸、肌醇、甘油磷胆碱、磷胆碱)进行了定量，在SNR=10的情况下，在8~14赫兹半高宽范围内，准确率为90%，标准偏差为10%。这些模拟没有考虑其他变化来源，包括涡流伪影、不完全的大分子基线去除和不完全的水抑制。无论如何，结果表明，4T短回波时间H-1-MRS的代谢物定量对信噪比和线宽敏感。版权所有(C)2007 John Wiley&Sons，Ltd.
The accuracy and precision of measurements of metabolite concentrations from short echo-time spectra has previously been characterized at 1.5 T as a function of signal-to-noise ratio (SNR) and peak linewidth. The purpose of this study was to characterize the systematic error in quantification of metabolite concentrations associated with linewidth and SNR for the major metabolites of interest in the short echo-time H-1-MR spectrum at 4 T. Simulated 4 T LASER localized spectra (TE = 46 ms) were generated with full width at half maximum (FWHM) over the range 4-14 Hz, and SNR over the range 5-500 by adding 100 Gaussian-distributed noise realizations at each combination of SNR and linewidth. Linewidth and SNR were treated as independent parameters, and therefore an increase in linewidth at a constant SNR resulted in increased metabolite areas. All spectra were fitted in the time domain using identical prior-knowledge and relative parameter starting values. Six metabolites (N-acetylaspartate, glutamate, creatine, myo-inositol, glycerophosphocholine, phosphocholine) were quantified with >90% accuracy and < 10% standard deviation at SNR = 10 for linewidths ranging from 8 to 14 Hz FWHM. These simulations did not consider additional sources of variation, including eddy current artifacts, incomplete macromolecule baseline removal, and incomplete water suppression. Regardless, the results show that metabolite quantification from 4 T short echo-time H-1-MRS is sensitive to SNR and linewidth. Copyright (C) 2007 John Wiley & Sons, Ltd.