Magnetic resonance imaging of 13C-labeled metabolites enhanced by parahydrogen-induced polarization (PHIP) can enable real-time monitoring of processes within the body. We introduce a robust, easily implementable technique for transferring parahydrogen-derived singlet order into 13C magnetization using adiabatic radio-frequency sweeps at μT fields. We experimentally demonstrate the applicability of this technique to several molecules, including some molecules relevant for metabolic imaging, where we show significant improvements in the achievable polarization, in some cases reaching above 60%. Furthermore, we introduce a site-selective deuteration scheme, where deuterium is included in the coupling network of a pyruvate ester to enhance the efficiency of the polarization transfer. These improvements are enabled by the fact that the transfer protocol avoids relaxation induced by strongly coupled quadrupolar nuclei.
@article{arxiv.2205.15709,
title = {Radio-Frequency Sweeps at {\mu}T Fields for Parahydrogen-Induced Polarization of Biomolecules},
author = {Alastair Marshall and Alon Salhov and Martin Gierse and Christoph Müller and Michael Keim and Sebastian Lucas and Anna Parker and Jochen Scheuer and Christophoros Vassiliou and Philipp Neumann and Fedor Jelezko and Alex Retzker and John W. Blanchard and Ilai Schwartz and Stephan Knecht},
journal= {arXiv preprint arXiv:2205.15709},
year = {2023}
}