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

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