Localized 2D J-resolved 1H MR spectroscopy: strong coupling effects in vitro and in vivo

A two-dimensional (2D) J-resolved MR spectroscopy sequence (2D J-PRESS), fully localized in three dimensions, has been implemented on a whole-body MR scanner. A modified PRESS sequence with [90 degrees-180 degrees-t1/2-180 degrees-t1/2-acquisition] was used for voxel localization. An incremental delay (t1/2) was added to the intervals before and after the last slice-selective 180 degree RF pulse to monitor the J-evolution in a localized 2D MR spectrum. Spectra were recorded with phantoms containing common cerebral metabolites--alanine, N-acetyl aspartate, glutamine, glutamate, taurine, myo-inositol, glucose, aspartate, GABA, and choline at 50 mM. In conformity with previously reported results, additional cross-peaks due to strong coupling were monitored in many metabolites. A brain phantom was developed to mimic the gray matter of human brain with the metabolites at physiological concentrations (0.5-12 mM). In vivo 2D J-PRESS spectra (n = 18) of healthy human brain were in conformity with those recorded from the brain phantom.