Quantification of Glutamate and Glutamine in the healthy brain via 1H in-vivo CSI MRS using LCModel is not reliable.

Glutamate and glutamine play an important role in CNS. Both are quantifiable via 1H in-vivo MRS, although a correct, separate quantification of both metabolites is often very challenging. In this study, 1H in-vivo CSI MRS was performed on ten healthy subjects, using the CSI sequences PRESS and Semi-LASER with TE=40ms,60ms,80ms,100ms and 135ms at 3T. The inner 64 spectra of each CSI matrix at each TE were averaged to a single spectrum. Averaged spectra were analysed using LCModel. The quantification of glutamate and glutamine, using this method, which is also a popular approach in MRS research, was shown to be inconsistent.