Magnetic resonance imaging characteristics of six radiofrequency electrodes in a phantom study.
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.
Aubé
Christophe
C
Department of Radiology, University Hospital of Angers, Angers, France.
Schmidt
Diethard
D
Brieger
Jens
J
Schenk
Martin
M
Helmberger
Thomas
T
Koenig
Claudius W
CW
Schick
Fritz
F
Claussen
Claus D
CD
Pereira
Philippe L
PL
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