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Effect of signal‐to‐noise ratio and spectral linewidth on metabolite quantification at 4 T
Author(s) -
Bartha Robert
Publication year - 2007
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1122
Subject(s) - laser linewidth , metabolite , full width at half maximum , signal to noise ratio (imaging) , nuclear magnetic resonance , chemistry , spectral line , analytical chemistry (journal) , physics , optics , laser , chromatography , astronomy , biochemistry
Abstract The accuracy and precision of measurements of metabolite concentrations from short echo‐time spectra has previously been characterized at l.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 1 H‐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 1 H‐MRS is sensitive to SNR and linewidth. Copyright © 2007 John Wiley & Sons, Ltd.