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Parahydrogen‐induced polarization (PHIP) is an inexpensive way to produce hyperpolarized molecules with polarization levels of >10 % in the solution‐state, but is strongly limited in generality since it requires chemical reactions/ interactions with H2. Here we report a new method to widen the scope of PHIP hyperpolarization: a source molecule is produced via PHIP with high 13C polarization, and precipitated out of solution together with a target species. Spin diffusion within the solid carries the polarization onto 13C spins of the target, which can then be dissolved for solution‐state applications. We name this method PHIP‐SSD (PHIP with solid‐state spin diffusion) and demonstrate it using PHIP‐polarized [1‐13C]‐fumarate as the source molecule, to polarize different 13C‐labelled target molecules. 13C polarizations of between 0.01 and 3 % were measured on [1‐13C]‐benzoic acid, depending on the molar ratio of fumarate:benzoate in the solid state. We also show that PHIP‐SSD does not require specific co‐crystallization conditions by grinding dry powders of target molecules together with solid fumarate crystals, and obtain 13C signal enhancements of between 100 and 200 on [13C,15N2]‐urea, [1‐13C]‐pyruvate, and [1‐13C]‐benzoic acid. This approach appears to be a promising new strategy for facile hyperpolarization based on PHIP. [ABSTRACT FROM AUTHOR]

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