title: Magnetic resonance imaging characteristics of six radiofrequency electrodes in a phantom study.
abstract: OBJECTIVE
  To evaluate and compare visibility and artifacts in magnetic resonance (MR) compatible radiofrequency (RF) electrodes for MR-guided RF ablation.
  
  
  METHODS
  Six different MR compatible electrodes for RF ablation including two internally cooled single needles, one internally cooled cluster needle, two expandable needles and one perfused needle were tested in a phantom study at 0.2 Tesla and at 1.5 Tesla field strength. Fluoroscopic, T1- and T2-weighted fast spin echo (FSE) and gradient echo (GE) sequences, which are usually used for MR-guided interventions, were evaluated. Qualitative and quantitative evaluations were performed. Length, width, noise, tip artifacts, global artifacts and global visualization of the RF electrodes that showed all sequences at different angles.
  
  
  RESULTS
  Qualitative analysis showed that electrodes were well visualized at all angles and sequences and on both MR imagers. Quantitative analysis showed that artifact-induced widening of the shaft was increased in all electrodes by: a). use of fluoroscopic sequences, GE sequences, and fat saturation, b). increasing the angle between the needle and main magnetic field, and c). high field strength (1.5 T). Expandable needles produced fewer tip artifacts but broader signal voids along the shaft compared to nonexpandable needles. Cluster electrodes produced less widening than the other electrodes.
  
  
  CONCLUSIONS
  Visibility and artifacts in all six MR compatible RF electrodes are satisfactory and these electrodes could be used for MR-guided radiofrequency ablation procedures.
authors.affiliation: Department of Radiology, University Hospital of Angers, Angers, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Aubé
authors.forename: Diethard
authors.initials: D
authors.lastname: Schmidt
authors.forename: Jens
authors.initials: J
authors.lastname: Brieger
authors.forename: Martin
authors.initials: M
authors.lastname: Schenk
authors.forename: Thomas
authors.initials: T
authors.lastname: Helmberger
authors.forename: Claudius W
authors.initials: CW
authors.lastname: Koenig
authors.forename: Fritz
authors.initials: F
authors.lastname: Schick
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
mesh_terms: D016477:Artifacts; D017115:Catheter Ablation / Q000295:instrumentation; D004567:Electrodes, Implanted; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009339:Needles; D010477:Perfusion; D019047:Phantoms, Imaging; D016896:Treatment Outcome