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This project aims to enhance the NMR signal intensity for MRI applications by means of Dynamic Nuclear Polarization (DNP) at a magnetic field strength of 1.5 T. In contrast to other approaches the hyperpolarization of the nuclear spins of metabolites is achieved in the liquid state with a microwave resonator situated inside the bore of the MRI magnet. Therefore, we developed a 42 GHz frequency resonance structure for liquid samples, which can be operated under continuous flow conditions. [1]

[1] Krummenacker, J., Denysenkov, V., Terekhov, M., Schreiber, L. and Prisner, T.F. (2012), DNP in MRI: An in-bore approach at 1,5 T. J. Magn. Reson., 215, 94-99. doi: 10.1016/j.jmr.2011.12.015
Deutsches Patent Nr. 10 2010 017 568.

In this setup, a liquid state flow-through DNP polarizer was developed to be operated in the bore of a commercial 1.5 T MRI tomograph. The microwave excitation at 42 GHz EPR frequency is provided by a home-built source (left) and transmitted into the magnet through a 3 m waveguide. The DNP polarizer (middle) produces a constant flow of hyperpolarized liquid sample, which can then be employed in imaging experiments (right).