Cerebral quantification of N-acetyl aspartate, aspartate, and glutamate levels in local structures of the human brain using J-editing of 1H magnetic resonance spectra in vivo

A procedure was developed for the first time for simultaneous in vivo quantification of local aspartate and glutamate concentrations in the human brain using 1H magnetic resonance spectroscopy (1H MRS) and spectral J-editing. The MEGA-PRESS pulse sequence was modified to observe β-CH2 nonequivalent proton resonances of aspartate (δ 2.65 and 2.80) and glutamate (δ 2.04 and 2.12) overlapped by signals of other metabolites. The frequencies, frequency selective pulse durations, and optimal echo times were selected by simulation and experimentally (for phantoms and in the brain in vivo).