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Brown TR , Stoyanova R
NMR spectral quantitation by principal-component analysis .2. Determination of frequency and phase shifts
Journal of Magnetic Resonance Series B. 1996 Jul;112(1) :32-43
PMID: ISI:A1996UW49200005   
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This paper extends the use of principal-component analysis in spectral quantification to the estimation of frequency and phase shifts in a single resonant peak across a series of spectra. The estimated parameters can be used to correct the spectra accordingly, resulting in more accurate peak-area estimation. Further, the removal of the variations in phase and frequency caused by instrumental and experimental fluctuations makes it possible to determine more accurately the remaining variations, which bear biological significance. The procedure is demonstrated on simulated data, a 3D chemical-shift-imaging dataset acquired from a cylinder of inorganic phosphate (P-i), and a set of 736 P-31 NMR in vivo spectra taken from a kinetic study of rat muscle energetics. In all cases, the procedure rapidly and automatically identifies the frequency and phase shifts present in the individual spectra. In the kinetic study, the procedure is used twice, first to adjust the phase and frequency of a reference peak (phosphocreatine) and then to determine the individual frequencies of the P-i peak in each of the spectra which further can be used for estimation of pH changes during the experiment. (C) 1996 Academic Press, Inc.
Times Cited: 18 English Article UW492 J MAGN RESONANCE SER B