title: Exchange-induced relaxation in the presence of a fictitious field.
abstract: In the present study we derive a solution for two site fast exchange-induced relaxation in the presence of a fictitious magnetic field as generated by amplitude and frequency modulated RF pulses. This solution provides a means to analyze data obtained from relaxation experiments with the method called RAFFn (Relaxation Along a Fictitious Field of rank n), in which a fictitious field is created in a coordinate frame undergoing multi-fold rotation about n axes (rank n). The RAFF2 technique is relevant to MRI relaxation methods that provide good contrast enhancement for tumor detection. The relaxation equations for n=2 are derived for the fast exchange regime using density matrix formalism. The method of derivation can be further extended to obtain solutions for n>2.
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Sorce
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Mangia
authors.affiliation: A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Liimatainen
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Garwood
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, MN, USA. Electronic address: shalom@cmrr.umn.edu.
authors.forename: Shalom
authors.initials: S
authors.lastname: Michaeli
mesh_terms: D000465:Algorithms; D004574:Electromagnetic Fields; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*
keywords: Exchange; Fictitious fields; High rotating frames; Relaxations