Lactate topography of the human brain using hyperpolarized ¹³C-MRI

Lactate is now recognized as an important intermediate in brain metabolism, but its role is still under investigation. In this work we mapped the distribution of lactate and bicarbonate produced from intravenously injected ¹³C-pyruvate over the whole brain using a new imaging method, hyperpolarized ¹³C MRI (N = 14, ages 23 to 77). Segmenting the ¹³C-lactate images into brain atlas regions revealed a pattern of lactate that was preserved across individuals. Higher lactate signal was observed in cortical grey matter compared to white matter and was highest in the precuneus, cuneus and lingual gyrus. Bicarbonate signal, indicating flux of [1-¹³C]pyruvate into the TCA cycle, also displayed consistent spatial distribution. One-way ANOVA to test for significant differences in lactate among atlas regions gave F = 87.6 and p < 10^-6. This report of a "lactate topography" in the human brain and its consistent pattern is evidence of region-specific lactate biology that is preserved across individuals.