Potential risks and artifacts of magnetic resonance imaging of self-expandable esophageal stents.
BACKGROUND
Several types of coated and uncoated self-expandable stents composed of various metals are available for palliation of malignant esophageal stenoses and fistulas. We encountered poor visualization of the mediastinum and skeletal axis with magnetic resonance imaging in a patient with a Gianturco self-expandable stent.


METHODS
To evaluate potential problems, such as stent migration in the magnetic field of the magnetic resonance scanner (MRI) and artifacts in the images, we studied four types of expandable stents: the Ultraflex (titanium alloy), the covered Wall stent (nitinol), the Gianturco stent (Cook), and the modified Gianturco stent (Song)-the last two being made of stainless steel.


RESULTS
An appreciable attraction force and torque, as measured ex vivo by suspending the stent in a Perspex device, was found for both Gianturco stents. In particular, the Gianturco (Cook) stent is pulled toward the head with a force of 7g; however, it is uncertain whether this is a potential risk for dislodgement. In addition, gross artifacts in the images, studied by putting the stents in a cylindric phantom filled with a diluted gadolinium solution, made the magnetic resonance useless for imaging in a wide area around the Gianturco stents of stainless steel. No problems with magnetic resonance image quality were encountered for the titanium-based Ultraflex and Wall stents.


CONCLUSIONS
Specific information on the type of stent is necessary before a magnetic resonance imaging examination is planned.
Taal
B G
BG
Department of Gastroenterology, Netherlands Cancer Institute/Antoni van Leeuwenhoekhuis, Amsterdam.
Muller
S H
SH
Boot
H
H
Koops
W
W
D016477:Artifacts; D001983:Bronchial Fistula / Q000628:therapy*; D004937:Esophageal Fistula / Q000628:therapy*; D005260:Female; D005548:Foreign-Body Migration / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D015607:Stents / Q000009:adverse effects