Hyperpolarization Techniques in Magnetic Resonance Spectroscopy

Magnetic resonance spectroscopy (MRS) and imaging (MRI) are indispensable in both fundamental research and clinical diagnostics, yet their inherent sensitivity is limited by the small population differences between nuclear spin states at thermal equilibrium. Hyperpolarisation techniques overcome this barrier by artificially boosting nuclear spin polarisation by several orders of magnitude, thereby amplifying signal intensities and enabling rapid, low‐concentration experiments. Dynamic nuclear polarisation (DNP) employs microwave irradiation at cryogenic temperatures to transfer polarisation from free radicals to target nuclei, while parahydrogen‐induced polarisation (PHIP) and its variants, such as side‐arm hydrogenation (PHIP‐SAH) and signal amplification by reversible exchange (SABRE), exploit the singlet state of parahydrogen to enrich nuclear spin populations under mild conditions. Photo‐chemically induced dynamic nuclear polarisation (photo-CIDNP) uses light‐driven radical pair mechanisms to hyperpolarise nuclei in solution. Collectively, these approaches have transformed metabolic imaging, fragment‐based drug discovery and the interrogation of fast biochemical reactions. Current research focuses on extending polarisation lifetimes, simplifying hardware, broadening substrate scope and integrating hyperpolarisation modules with existing MR platforms to facilitate routine in vivo studies and high‐throughput screening.

Research from Nature Portfolio

Researchers have advanced PHIP strategies to hyperpolarise biologically relevant carboxylate metabolites. Tailored hydrogenable precursors enable transfer of parahydrogen singlet order to 13C nuclei in acetate and pyruvate, followed by chemical cleavage to yield end products with high polarisation levels. This methodology expands the substrate repertoire beyond unsaturated precursors and lays the groundwork for rapid preparation of hyperpolarised metabolites without cryogenic infrastructure. In parallel, the PHIP‐SAH approach has been implemented in vivo to generate hyperpolarised [1-13C]pyruvate within seconds and map its conversion to lactate in mouse hearts. Metabolic imaging at low magnetic field strengths revealed altered pyruvate-to-lactate exchange rates in a cardiomyopathy model, demonstrating the capacity to detect early tissue dysfunction prior to conventional echocardiography.

Hyperpolarization Techniques in Magnetic Resonance Spectroscopy publication trend

The graph below shows the total number of articles in hyperpolarization techniques in magnetic resonance spectroscopy across all publications each year (not limited to Nature Index journals).

Technical terms

Hyperpolarisation: The process of increasing nuclear spin population differences far beyond thermal equilibrium to enhance magnetic resonance signals.

Dynamic Nuclear Polarisation (DNP): A technique that transfers polarisation from unpaired electron spins to nuclear spins via microwave irradiation at low temperature.

Parahydrogen‐Induced Polarisation (PHIP): A chemistry‐based method that uses the singlet spin state of parahydrogen to enrich nuclear polarisation upon hydrogenation of target molecules.

Signal Amplification by Reversible Exchange (SABRE): A variant of PHIP in which parahydrogen and the substrate transiently bind a catalyst, transferring polarisation without permanent chemical modification.

Photo-Chemically Induced Dynamic Nuclear Polarisation (photo-CIDNP): A light‐driven technique generating radical pairs that yield selective nuclear hyperpolarisation in solution.

References

1. Spin Hyperpolarization in Modern Magnetic Resonance. Chemical Reviews (2023).
2. Ultrafast Fragment Screening Using Photo-Hyperpolarized (CIDNP) NMR. Journal of the American Chemical Society (2023).
3. Parahydrogen‐Polarized [1‐13C]Pyruvate for Reliable and Fast Preclinical Metabolic Magnetic Resonance Imaging. Advanced Science (2023).
4. ParaHydrogen Induced Polarization of 13C carboxylate resonance in acetate and pyruvate. Nature Communications (2015).
5. The 13C hyperpolarized pyruvate generated by ParaHydrogen detects the response of the heart to altered metabolism in real time. Scientific Reports (2018).