Hyperpolarized Multi-organ Spectroscopy of Liver and Brain Using 1-13C-Pyruvate Enhanced via Parahydrogen

Hyperpolarization in nuclear magnetic resonance boosts the signals by several orders of magnitude. Using the singlet spin order of parahydrogen to create large non-equilibrium spin polarization is a fast approach to obtain hyperpolarized metabolites in seconds. In recent years, it has attracted particular interest in the field of biomedicine because signal-enhanced and 13C-enriched metabolites allow for real-time metabolic investigations in combination with imaging in vivo. With this, metabolism can be traced and characterized with spatial selectivity in the body. Here, we introduce a method to use signal-enhanced metabolites to study multiple organs in separate injections to obtain real-time kinetics in vivo of these organs. Using hyperpolarized 1-13C-pyruvate, we measured the kinetics of the conversion from pyruvate to lactate in the brain and the liver of mice. This we did by injecting the hyperpolarized pyruvate two times within half an hour and using each injection to measure the spectra of one region of interest. Organ cross-talk and especially how different organs affect each other in diseases is of major interest and poorly understood, because of the high complexity of biological systems. With the proof-of-principle study provided here, we are introducing a new tool to study organ-related interaction in vivo. It allows the characterization of different organs of the same animal within half an hour, which is enabled by the fast signal enhancement achieved with parahydrogen.