Improved quantification precision of human brain short echo-time (1) H magnetic resonance spectroscopy at high magnetic field: a simulation study.

PURPOSE: The gain in quantification precision that can be expected in human brain (1) H MRS at very high field remains a matter of debate. Here, we investigate this issue using Monte-Carlo simulations. METHODS: Simulated human brain-like (1) H spectra were fitted repeatedly with different noise realizations using LCModel at B0 ranging from 1.5T to 11.7T, assuming a linear increase in signal-to-noise ratio with B0 in the time domain, and assuming a linear increase in linewidth with B0 based on experimental measurements. Average quantification precision (Cramér-Rao lower bound) was then determined for each metabolite as a function of B0 . RESULTS: For singlets, Cramér-Rao lower bounds improved (decreased) by a factor of ∼ B0 as B0 increased, as predicted by theory. For most J-coupled metabolites, Cramér-Rao lower bounds decreased by a factor ranging from B0 to B0 as B0 increased, reflecting additional gains in quantification precision compared to singlets owing to simplification of spectral pattern and reduced overlap. CONCLUSIONS: Quantification precision of (1) H magnetic resonance spectroscopy in human brain continues to improve with B0 up to 11.7T although peak signal-to-noise ratio in the frequency domain levels off above 3T. In most cases, the gain in quantification precision is higher for J-coupled metabolites than for singlets.