Drug eluting coronary stent: in vitro evaluation of magnet resonance safety at 3 Tesla.
OBJECTIVE
To evaluate MR safety at 3 Tesla for a drug eluting coronary stent.


METHODS
A drug eluting coronary stent (Endeavor, cobalt alloy, Medtronic Vascular, Santa Rosa, CA) was evaluated for magnetic field interactions, heating, and artifacts at 3 Tesla. MRI-related heating was assessed with the stent in a gelled saline-filled phantom using a transmit/received RF body coil with a whole body averaged SAR of 2.0 W/kg. Artifacts were characterized using T1-weighted, spin echo, and gradient echo pulse sequences.


RESULTS
The stent exhibited minor magnetic field interactions that will not cause migration. Heating was not substantial (+0.5 degrees C). Artifacts may create a problem if the area of interest is in the same area or close to the stent (e.g., for a T1-weighted, spin echo pulse sequence, within approximately 16 mm; for a gradient echo pulse sequence, within approximately 23 mm). Conclusion. The findings indicated that it would be safe for a patient with this cobalt alloy-based, drug-eluting coronary stent to undergo MRI at 3 Tesla or less. Importantly, because of the relative lack of magnetic field interactions, MRI may be performed immediately after implantation.
Shellock
Frank G
FG
Keck School of Medicine, University of Southern California, Los Angeles, California, USA. frank.shellock@gte.net
Forder
John R
JR
D016477:Artifacts; D020099:Coated Materials, Biocompatible; D023903:Coronary Restenosis / Q000517:prevention & control; D016503:Drug Delivery Systems; D004574:Electromagnetic Fields; D004869:Equipment Safety; D006358:Hot Temperature; D006801:Humans; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D019047:Phantoms, Imaging; D015607:Stents; D013696:Temperature; D019415:Torque
D020099:Coated Materials, Biocompatible