Simulation study of low-field proton magnetic resonance spectroscopy using optically pumped magnetometers

Abstract

We numerically investigated the feasibility of low-field magnetic resonance spectroscopy (MRS) using optically pumped magnetometers (OPMs). Low magnetic fields reduce signal strength and spectral resolution, challenging reliable metabolite quantification. To address these issues, we performed Bloch-equation–based simulations at 0.01–7 T using aqueous phantoms. We compared chemical shift selective and inversion recovery (IR) methods for water suppression. We also evaluated signal detection using both radio frequency coils and OPMs. The IR method, relying on T1 contrast rather than frequency selectivity, effectively suppressed water signals down to 0.1 T. The signal-to-noise ratio (SNR) of Glu increased below 0.7 T. OPMs maintained nearly constant SNR across 0.01–1 T and outperformed coils below 1 T. In mixed-metabolite settings, however, spectral overlap and IR-induced co-suppression impaired detection—particularly for Gln below 0.1 T. These results show that IR and OPMs offer complementary advantages for low-field MRS, while spectral resolution remains a challenge. This work provides a theoretical basis for enhancing low-field MRS techniques and expanding access to metabolic diagnostics in clinical and research settings.