Reproducibility of the Determination of ¹³C‐Labeling of Glutamate and Glutamine in the Human Brain Using selPOCE‐MRS at 7 T Upon [U‐¹³C]–Labeled Glucose Infusion

Glutamate (Glu) is the major excitatory neurotransmitter in the central nervous system. The measurement of Glu/glutamine (Gln) neurotransmitters in the brain provides valuable insights into the dynamic aspects of neuroenergetics and neurotransmitter cycles and can be accomplished through the detection of 13 C‐labeling of Glu and Gln during the administration of 13 C‐labeled glucose. Our goal is to evaluate the reproducibility of selective proton‐observed, carbon‐edited (selPOCE) MRS at 7 T for the detection of 13 C‐labeled Glu and Gln in the human brain. Data of three healthy participants, who were scanned twice at 7 T while undergoing [U‐ 13 C]‐glucose infusion for 120 min, were used to detect 13 C‐labeled Glu and Gln in the brain, using selPOCE‐STEAM‐MRS. There was a rapid increase of plasma glucose 13 C fractional enrichment (FE) during the first 20 min of infusion, followed by a steady state of plasma glucose 13 C FE until the end of the [U‐ 13 C]‐glucose infusion. The time courses of 13 C‐labeling of Glu and Gln were similar for test/retest. The test/retest variability was 15.8% for 13 C‐Glu and 33.3% for 13 C‐Gln. Knowing the variability of these readings using selPOCE‐STEAM‐MRS can inform the application to future studies on disease‐specific alterations in Glu/Gln cycling.