When acquired at short echo-time, the proton MRS signals contain contributions from metabolites and water, and a large baseline
(‘background’) component. The background contributions in proton short echo-time MRS signals make accurate and reliable quantification
difficult. The purpose of the present study was to compare the influence of the background-accommodation strategy on the metabolite
concentration estimates at 7 T using QUEST. Two strategies were investigated to accommodate the background, (1) the measured
background signal was incorporated in the metabolite basis-set; and (2) the background signal was estimated and subtracted
from the in vivo signal using Subtract-QUEST. The influence of the background-accommodation strategy was addressed with the
aid of Monte Carlo and in vivo studies. For the signals considered in this study, statistically significant differences between
the in vivo concentration estimates using the two approaches were observed for three metabolites namely Cho, NAA, and Tau.
The observed underestimation of the ‘background’ estimates using Subtract-QUEST led to an overestimation of these metabolite
estimates. Consequently, we can conclude that, including the ‘background’ signal in the metabolite basis-set would lead to
more accurate quantifications at higher magnetic field strengths when the differences between the apparent relaxation times
of the ‘background’ and the metabolite signals are reduced. However, the use of the Subtract-QUEST method is the method of
choice when measurement time is critical especially for diseased animals.
Keywords Magnetic resonance spectroscopy - Signal processing - Quantification - Brain metabolites - Macromolecular component handling - MRS acquisition