Localized 2D J‐resolved H MR spectroscopy of human brain tumors in vivo

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Abstract
Application of two‐dimensional (2D) J‐resolved MR spectroscopy, fully localized in three dimensions to monitor the metabolites in human brain tumors in vivo on a whole body MR scanner is presented. A modified PRESS sequence with [90° – 180° – t1/2 – 180° – t1/2‐acquisition] was used for voxel localization (2D J point‐resolved spectroscopy [PRESS]); chemical shift selective (CHESS) sequence was used for suppression of water. The incremental delay (t1/2) added to the intervals before and after the last slice‐selective 180° RF pulse allowed the monitoring of the J‐evolution in a localized 2D NMR spectrum. The addition of the second frequency dimension in 2D J‐resolved spectroscopy to encode the indirect spin‐spin coupling allowed the visualization of lactate peaks not observed in the 1D MR spectrum because of severe overlap with lipid peaks. 2D spectra of a two‐layer phantom with 100 mM alanine and corn oil and also from three patients with tumors are presented here. The 2D spectra show that the J‐coupled lactate peaks could be separated even when the lipids peaks severely overlap.