Jan Falk Dechent's research while affiliated with Max Planck Institute for Polymer Research and other places

Despite their wide applicability in natural sciences, NMR and MRI still suffer from their inherently low sensitivity. This can be overcome by hyperpolarisation techniques, such as parahydrogen-induced polarisation and dynamic nuclear polarisation. Here, we focus on the generation of 1H-hyperpolarised substances with both methods. We especially address the severe lifetime issue of the accomplished 1H hyperpolarisation by demonstrating the production of hyperpolarised liquids in a continuous flow fashion and the storage of hyperpolarisation in slowly relaxing singlet states. Another problem of hyperpolarised proton NMR and MRI is the generation of contrast between a small amount of hyperpolarised molecules and a vast thermal background signal. In this contribution, we show the possibility to use the special signal pattern that is inherent to the hyperpolarisation method to generate excellent MRI contrast which may open up unprecedented opportunities to use the standard MRI nucleus 1H, for example, biomedical applications in future.

A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for (1)H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screens the small amount of hyperpolarized ones. Here, we describe a method giving rise to high (1)H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling induced rephasing of the NMR signal of molecules hyperpolarized via PHIP and it can easily be implemented in common pulse sequences. We discuss several scenarios with different or equal dephasing times T(2)* for the hyperpolarized and thermally polarized compounds and verify our approach by experiments. This method may open up unprecedented opportunities to use the standard MRI nucleus (1)H for e.g. metabolic imaging in the future.