Parahydrogen-Polarized [1-13C]Pyruvate For Reliable and Fast Preclinical Metabolic Magnetic Resonance Imaging

Hyperpolarization techniques increase nuclear spin polarization by more than four orders of magnitude, enabling metabolic MRI. Even though the hyperpolarization has shown clear value in clinical studies, the complexity, cost and slowness of current equipment limits its widespread use. Here, we demonstrate a polarization procedure of [1-13C]pyruvate based on parahydrogen-induced polarization by side-arm hydrogenation (PHIP-SAH) in an automated polarizer. It was benchmarked in a study with 48 animals against a commercial dissolution dynamic nuclear polarization (DNP) device. We obtained purified, concentrated (≈ 70-160 mM) and highly hyperpolarized (≈ 18 %) solutions of pyruvate at physiological pH for volumes up to 2 ml within 85 seconds in an automated process. The safety profile, image quality, as well as the quantitative perfusion and pyruvate-to-lactate ratios, were equivalent for PHIP and DNP, rendering PHIP a viable alternative to established hyperpolarization techniques.