title: Spatial distribution of RF-induced E-fields and implant heating in MRI.
abstract: The purpose of this study was to assess the distribution of RF-induced E-fields inside a gel-filled phantom of the human head and torso and compare the results with the RF-induced temperature rise at the tip of a straight conductive implant, specifically examining the dependence of the temperature rise on the position of the implant inside the gel. MRI experiments were performed in two different 1.5T MR systems of the same manufacturer. E-field distribution inside the liquid was assessed using a custom measurement system. The temperature rise at the implant tip was measured in various implant positions and orientations using fluoroptic thermometry. The results show that local E-field strength in the direction of the implant is a critical factor in RF-related tissue heating. The actual E-field distribution, which is dependent on phantom/body properties and the MR-system employed, must be considered when assessing the effects of RF power deposition in implant safety investigations.
authors.affiliation: Medizinische Klinik und Poliklinik I, Universität Würzburg, Würzburg, Germany. nordbeck@physik.uni-wuerzburg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Nordbeck
authors.forename: Florian
authors.initials: F
authors.lastname: Fidler
authors.forename: Ingo
authors.initials: I
authors.lastname: Weiss
authors.forename: Marcus
authors.initials: M
authors.lastname: Warmuth
authors.forename: Michael T
authors.initials: MT
authors.lastname: Friedrich
authors.forename: Philipp
authors.initials: P
authors.lastname: Ehses
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Geistert
authors.forename: Oliver
authors.initials: O
authors.lastname: Ritter
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
authors.forename: Harald H
authors.initials: HH
authors.lastname: Quick
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Bauer
mesh_terms: D001831:Body Temperature / Q000502:physiology* / Q000528:radiation effects*; D003198:Computer Simulation; D008279:Magnetic Resonance Imaging; D008954:Models, Biological; D019736:Prostheses and Implants; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012542:Scattering, Radiation