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The linear combination of model spectra (LCModel) calculation of a parameter for long-term quality control,k
T, was introduced, representing the ratio of the temporal and nominal intensities of CH3 groups of lactate and acetate in a quality control phantom. This procedure is a part of the quality assurance of the scanner
using fully automatic measurement and calculation ofk
T parameters, and utilizing Shewhart regulation control charts for continuous evaluation of the magnetic resonance (MR) scanner
setting. The application of thek
T parameter for the correction of in vivo data increases the precision of molar concentration determination by about 4%. This
was tested by the quantitative in vivo MR determination of the molar concentrations of 13 prominent metabolites (N-acetylaspartate (NAA),N-acetylaspartylgutamate, creatine and phosphocreatine (Cr), choline-containing compounds (Cho), myo-inositol, scyllo-inositol.,
γ-aminobutyric acid, glutamine, glutamate, glucose, lactate, alanine, taurine) in the white matter and hippocampus of the
brain in groups of volunteers, using a short echo time stimulated echo acquisition mode sequence (echo time =10 ms) and the
LCModel technique. The repeatability of the measurement of prominent metabolites such as NAA, Cr and Cho was found to be around
10% (relative standard deviation,n=6); precision in a group of volunteers (n=20 and 28, respectively) was in the range of approximately 13–20%. For other metabolites, which are measured with a lower
signal-to-noise ratio, the precision can be much lower. 相似文献