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In vivo 1H NMR spectroscopy of the human brain at high magnetic fields: metabolite quantification at 4T vs. 7T.

Tkác, Ivan
Oz, Gülin
Adriany, Gregor
Uğurbil, Kamil
Published in Magnetic Resonance in Medicine. 2009, vol. 62, no. 4, p. 868-79
Abstract 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 Cramér-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.
Keywords AdultAlgorithmsBrain/metabolismBrain ChemistryFemaleHumansMagnetic Resonance Spectroscopy/methodsMaleProtonsReproducibility of ResultsSensitivity and Specificity
PMID: 19591201
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Research group CIBM (863)
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TKÁC, Ivan et al. In vivo 1H NMR spectroscopy of the human brain at high magnetic fields: metabolite quantification at 4T vs. 7T. In: Magnetic Resonance in Medicine, 2009, vol. 62, n° 4, p. 868-79. doi: 10.1002/mrm.22086 https://archive-ouverte.unige.ch/unige:32957

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Deposited on : 2014-01-08

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