title: Radio-frequency current density imaging based on a 180 (°) sample rotation with feasibility study of full current density vector reconstruction.
abstract: Radio-frequency current density imaging (RF-CDI) is a technique that noninvasively measures current density distributions at the Larmor frequency utilizing magnetic resonance imaging. Previously implemented RF-CDI methods reconstruct the applied current density component J(z) along the static magnetic field of the imager [(B)\vec](0) (the z direction) based on the assumption that the z-directional change of the magnetic field component H(z) can be ignored compared to J(z). However, this condition may be easily violated in biomedical applications. We propose a new reconstruction method for RF-CDI, which does not rely on the aforementioned assumption. Instead, the sample is rotated by 180 (°) in the horizontal plane to collect magnetic resonance data from two opposite positions. Using simulations and experiments, we have verified that this approach can fully recover one component of current density. Furthermore, this approach can be extended to measure three dimensional current density vectors by one additional sample orientation in the horizontal plane. We have therefore demonstrated for the first time the feasibility of imaging the magnitude and phase of all components of a radio-frequency current density vector field.
authors.affiliation: Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada. dinghui.wang@utoronto.ca
authors.forename: Dinghui
authors.initials: D
authors.lastname: Wang
authors.forename: Weijing
authors.initials: W
authors.lastname: Ma
authors.forename: Tim P
authors.initials: TP
authors.lastname: Demonte
authors.forename: Adrian I
authors.initials: AI
authors.lastname: Nachman
authors.forename: Michael L G
authors.initials: ML
authors.lastname: Joy
mesh_terms: D000465:Algorithms; D000818:Animals; D003198:Computer Simulation; D005240:Feasibility Studies; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging