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Abstract

Purpose Macromolecular resonances (MM) arise mainly from cytosolic proteins and overlap with metabolites, influencing metabolite quantification. Macromolecules can serve as valuable biomarkers for diseases and pathologies. The objectives of this study were to characterize MM at 9.4T in the human brain (occipital and left parietal lobe) and to describe the RF coil setup used for MM acquisition in the two regions. Methods An adiabatic inversion pulse was optimised for metabolite nulling at 9.4T using double inversion recovery and was combined for the first time with metabolite cycled (MC) semi-LASER and appropriate coil configuration. MM spectra (seven volunteers) from two brain locations were averaged and smoothed creating MM templates, which were then parametrized using simulated Voigt-shaped lines within LCModel. Quantification was performed on individual data sets, including corrections for different tissue composition and the T1 and T2 relaxation of water. Results Our coil configuration method resulted in efficient math formula (>30 T/√kW) for both brain regions. The 15 MM components were detected and quantified in MM baselines of the two brain areas. No significant differences in concentration levels of MM between different regions were found. Two new MM peaks were reported (M7 M8). Conclusion Double inversion, which was combined with MC semi-LASER, enabled the acquisition of high spectral resolution MM spectra for both brain regions at 9.4T. The 15 MM components were detected and quantified. Two new MM peaks were reported for the first time (M7 M8) and preliminarily assigned to β-methylene protons of aspartyl-groups.