Comparison of fast field-cycling magnetic resonance imaging methods and future perspectives

Fast field-cycling (FFC) nuclear magnetic resonance relaxometry is a well-established method to

determine the relaxation rates as a function of magnetic field strength. This so-called nuclear mag-

netic relaxation dispersion gives insight into the underlying molecular dynamics of a wide range

of complex systems and has gained interest especially in the characterisation of biological tissues

and diseases. The combination of FFC techniques with magnetic resonance imaging (MRI) offers a

high potential for new types of image contrast more specific to pathological molecular dynamics.

This article reviews the progress in FFC-MRI over the last decade and gives an overview of the hard-

ware systems currently in operation. We discuss limitations and error correction strategies specific to

FFC-MRI such as field stability and homogeneity, signal-to-noise ratio, eddy currents and acquisition

time. We also report potential applications with impact in biology and medicine. Finally, we discuss

the challenges and future applications in transferring the underlying molecular dynamics into novel

types of image contrast by exploiting the dispersive properties of biological tissue or MRI contrast

agents.