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Hyperpolarization-enhanced magnetic resonance imaging can be used to
study biomolecular processes in the body, but typically requires nuclei such as
13C, 15N, or 129Xe due to their long spin‑polarization
lifetimes and the absence of a proton‑background signal from water and fat in the
images. Here we present a novel type of 1H imaging, in which
hyperpolarized spin order is locked in a nonmagnetic long-lived correlated (singlet)
state, and is only liberated for imaging by a specific biochemical reaction. In
this work we produce hyperpolarized fumarate via chemical reaction of a precursor
molecule with para-enriched hydrogen gas, and the proton singlet order
in fumarate is released as antiphase NMR signals by enzymatic conversion to
malate in D2O. Using this model system we show two pulse sequences
to rephase the NMR signals for imaging and suppress the background signals from
water. The hyperpolarization-enhanced 1H‑imaging modality presented
here can allow for hyperpolarized imaging without the need for low‑abundance,