Improved Quantification Precision of Human Brain Short Echo-Time 1H Magnetic Resonance Spectroscopy at High Magnetic Field: A Simulation Study

Purpose: The gain in quantification precision that can be expected in human brain H-1 MRS at very high field remains a matter of debate. Here, we investigate this issue using Monte-Carlo simulations. Methods: Simulated human brain-like H-1 spectra were fitted repeatedly with different noise realizations using LCModel at B-0 ranging from 1.5T to 11.7T, assuming a linear increase in signal-to-noise ratio with B-0 in the time domain, and assuming a linear increase in linewidth with B-0 based on experimental measurements. Average quantification precision (Cramer-Rao lower bound) was then determined for each metabolite as a function of B-0. Results: For singlets, Cramer-Rao lower bounds improved (decreased) by a factor of similar to root B-0 as B-0 increased, as predicted by theory. For most J-coupled metabolites, Cramer-Rao lower bounds decreased by a factor ranging from root B-0 to B-0 as B-0 increased, reflecting additional gains in quantification precision compared to singlets owing to simplification of spectral pattern and reduced overlap. Conclusions: Quantification precision of H-1 magnetic resonance spectroscopy in human brain continues to improve with B-0 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. (C) 2013 Wiley Periodicals, Inc.