Task activation results in regional 13C-lactate signal increase in the human brain

Abstract

Hyperpolarized-13C magnetic resonance imaging (HP-13C MRI) was used to image changes in 13C-lactate signal during a visual stimulus condition in comparison to an eyes-closed control condition. Whole-brain 13C-pyruvate, 13C-lactate and 13C-bicarbonate production was imaged in healthy volunteers (N = 6, ages 24–33) for the two conditions using two separate hyperpolarized 13C-pyruvate injections. BOLD-fMRI scans were used to delineate regions of functional activation. 13C-metabolite signal was normalized by 13C-metabolite signal from the brainstem and the percentage change in 13C-metabolite signal conditions was calculated. A one-way Wilcoxon signed-rank test showed a significant increase in 13C-lactate in regions of activation when compared to the remainder of the brain ((Formula presented.)). No significant increase was observed in 13C-pyruvate signal ((Formula presented.)) or 13C-bicarbonate signal ((Formula presented.)). The results show an increase in 13C-lactate production in activated regions that is measurable with HP-13C MRI.