title: Magnetic resonance imaging of alternating electric currents.
abstract: Electric Current Density Imaging (CDI) is a new modality of magnetic resonance imaging that enables electric current distribution imaging in conductive samples containing water. So far, two CDI techniques have been in use: DC-CDI operating at zero frequency and RF-CDI operating at the RF Larmor frequency. In this paper we present a new CDI technique, which extends the CDI frequency range to alternating electric currents (AC-CDI). First, a theoretical model for the electric current response to the alternating voltage is presented. Later, this model is used for the frequency analysis of the AC-CDI sequence. Additionally, the effect of off-resonance spins and imperfect refocusing RF pulses on the stability of the AC-CDI sequence and the echo formation is studied. The new theory is verified by experiments on a model system and compared to the other two methods: DC-CDI and RF-CDI. Finally, an application of the AC-CDI sequence to biological systems is demonstrated by an experiment on a wood twig in which an increase of approximately 30% was obtained at AC as compared to DC electric current.
authors.affiliation: Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: U
authors.initials: U
authors.lastname: Mikac
authors.forename: F
authors.initials: F
authors.lastname: Demsar
authors.forename: K
authors.initials: K
authors.lastname: Beravs
authors.forename: I
authors.initials: I
authors.lastname: Sersa
mesh_terms: D004560:Electricity; D008279:Magnetic Resonance Imaging / Q000379:methods; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D014934:Wood