Abstract
"Classical" magnetic resonance imaging (MRI) is based on imaging of water protons and the technique is commonly used in clinical and preclinical practice. The 19F nuclide has nuclear magnetic properties similar to those of 1H and can be used for MRI on common commercial scanners with only minor modifications.
The 19F MRI is a potentially interesting tool for preclinical or even clinical imaging. As there is no abundance of 19F in a living body, 19F MRI requires contrast agents (CAs) containing fluorine atoms and is presented as "hotspot" imaging.
In this text, we present how the current development of 19F MRI CAs is influenced by utilization of paramagnetic metal ions as relaxation agents through shortening the long 19F relaxation times. The theory behind the change of relaxation times is briefly introduced.
Influence of lanthanide(III) and transition metal ions on the relaxation properties of the 19F nucleus in defined molecules and in nanoobjects is reviewed and differences between complexes of these two metal ion families are discussed. The 19F tracers are best utilized as responsive MRI CAs and various responsive modes of the probes are reviewed and evaluated.
As 19F MRI requires some special consideration about acquisition techniques, the main differences between 1H and 19F MRI are discussed. Briefly, some outlook for the technique is suggested.