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 magnetic 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 hardware 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.
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Field-cycling; FFC-MRI; delta relaxation enhanced MR; dispersion; NMRDCONTACT Markus Bödenler m.boedenler@tugraz.at * These authors have equally contributed to this work. of the scanner. Differences in the underlying relaxation behaviour at B 0 , and therefore changes in image contrast, can be used to distinguish between healthy and pathological tissues for many diseases [1]. However, contrast mechanisms may change dramatically with the applied magnetic field strength, and these changes can be exploited to obtain new information for medical diagnosis. One way to access field-dependant information is by using Fast Field-Cycling (FFC) methods.FFC Nuclear Magnetic Resonance (NMR) relaxometry is an established method to measure the changes