Probing compartment-specific diffusion in the brain with ¹³C diffusion-weighted MRS of hyperpolarized pyruvate and lactate: initial results

Synopsis

Here we propose to use ¹³C diffusion-weighted MRS of hyperpolarized pyruvate and lactate to probe diffusion properties in distinct compartments of the mouse brain, tentatively extracellular (ECS) and intracellular spaces (ICS). Hyperpolarized ¹³C-pyruvate is injected intravenously and taken up by the brain before entering cells, where it is quickly converted to lactate, so that ¹³C-pyruvate concentration in ICS must remain low, while newly produced ¹³C-lactate should remain predominantly intracellular during the relatively short measurement time. We measure faster diffusion for pyruvate even after removing IVIM effect, suggesting faster diffusion in the ECS, and slow release of lactate in the ECS.