In vivo detection of 13C isotopomer turnover in the human brain by sequential infusion of 13C labeled substrates

[Display omitted] ► Feasibility of 13C isotopomer MRS of human brain is demonstrated. ► [U–13C6]glucose and [2-13C]glucose generate doublets and singlets of brain amino acids, respectively. ► Different 13C labeling pathways are simultaneously detected in the human brain at 3T. This study demonstrates the feasibility of simultaneously detecting human brain metabolites labeled by two substrates infused in a sequential order. In vivo 13C spectra of carboxylic/amide carbons were acquired only during the infusion of the second substrate. This approach allowed dynamic detection of 13C labeling from two substrates with considerably different labeling patterns. [2-13C]glucose and [U–13C6]glucose were used to generate singlet and doublet signals of the same carboxylic/amide carbon atom, respectively. Because of the large one-bond 13C–13C homonuclear J coupling between a carboxylic/amide carbon and an aliphatic carbon (∼50Hz), the singlet and doublet signals of the same carboxylic/amide carbon were well distinguished. The results demonstrated that different 13C isotopomer patterns could be simultaneously and distinctly measured in vivo in a clinical setting at 3T.