Detection of 13C labeling of glutamate and glutamine in human brain by proton magnetic resonance spectroscopy

A proton magnetic resonance spectroscopy (MRS) technique was used to measure 13 C enrichments of glutamate and glutamine in a 3.5 × 1.8 × 2 cm 3 voxel placed in the dorsal anterior cingulate cortex of five healthy participants after oral administration of [U- 13 C]glucose. Strong pseudo singlets of glutamate and glutamine were induced to enhance the signal strength of glutamate and glutamine. This study demonstrated that 13 C labeling of glutamate and glutamine can be measured with the high sensitivity and spatial resolution of 1 H MRS using a proton-only MRS technique with standard commercial hardware. Furthermore, it is feasible to measure 13 C labeling of glutamate and glutamine in limbic structures, which play major roles in behavioral and emotional responses and whose abnormalities are involved in many neuropsychiatric disorders.