Quantification of the neurochemical profile using simulated macromolecule resonances at 3 T

The broad resonances underlying the entire 1H NMR spectrum of the brain, ascribed to macromolecules, can influence metabolite quantification. At the intermediate field strength of 3T, distinct approaches for the determination of the macromolecule signal, previously used at either 1.5 or 7T and higher, may become equivalent. The aim of this study was to evaluate, at 3T for healthy subjects using LCModel, the impact on the metabolite quantification of two different macromolecule approaches: (i) experimentally measured macromolecules; and (ii) mathematically estimated macromolecules. Although small, but significant, differences in metabolite quantification (up to 23% for glutamate) were noted for some metabolites, 10 metabolites were quantified reproducibly with both approaches with a CramerRao lower bound below 20%, and the neurochemical profiles were therefore similar. We conclude that the mathematical approximation can provide sufficiently accurate and reproducible estimation of the macromolecule contribution to the 1H spectrum at 3T. Copyright (c) 2013 John Wiley & Sons, Ltd.