19F-MRI using Hyperpolarized Substrates Generated via Parahydrogen-Transfer

Introduction F attracts increasingly more attention for MRI and MRS investigations due to its interesting MR characteristics that include a 100% natural abundance and 84% sensitivity in comparison to H. Although F has a wide chemical shift range (~ 300 ppm?) the essentially complete lack of a natural background signal in body tissues qualify fluorinated substrates as excellent reporter molecules. They allow the simultaneous detection of multiple signals from separate molecules in MRS investigations, or the direct pharmacokinetic analysis of anatomical and functional sites in the living system due to the high sensitivity to changes in the microenvironment. Many pharmaceuticals contain a fluorine atom allowing detection of pharmacokinetics and their metabolism. Even passive substrates like perfluorocarbons can be used to investigate anatomical properties such as lung volume. Although the sensitivity of F is rather high, the concentration of F-containing reporter molecules is usually is limited in vivo and the signal remains very weak. Enhancement of the F signal is therefore essential for using high-sensitivity reporter molecules. We have therefore applied an effective signal enhancement provided by the PHIP hyperpolarization method (ParaHydrogen Induced Polarization) as a new promising strategy towards MR-based molecular imaging.