Detection of (13)C 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.