In vivo 13C spectroscopy in the rat brain using hyperpolarized [1-13C]pyruvate and [2-13C]pyruvate

The low sensitivity of 13C spectroscopy can be enhanced using dynamic nuclear polarization. Detection of hyperpolarized [1-13C]pyruvate and its metabolic products has been reported in kidney, liver, and muscle. In this work, the feasibility of measuring 13C signals of hyperpolarized 13C metabolic products in the rat brain in vivo following the injection of hyperpolarized [1-13C]pyruvate and [2-13C]pyruvate is investigated. Injection of [2-13C]pyruvate led to the detection of [2-13C]lactate, but no other downstream metabolites such as TCA cycle intermediates were detected. Injection of [1-13C]pyruvate enabled the detection of both [1-13C]lactate and [13C]bicarbonate. A metabolic model was used to fit the hyperpolarized 13C time courses obtained during infusion of [1-13C]pyruvate and to determine the values of VPDH and VLDH.