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 ¹H MRS at very high field remains a matter of debate. Here, we investigate this issue using Monte-Carlo simulations. Methods Simulated human brain-like ¹H 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 B ₀. 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 √B ₀ 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 ¹H 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.