Related Experiment Videos
Middle ear prosthesis displacement in high-strength magnetic fields.
M D Williams1, P J Antonelli, L S Williams
1Department of Otolaryngology, University of Florida, Gainesville 32610-0264, USA.
Summary
Middle ear prostheses made from stainless steel showed movement in high magnetic fields during ex vivo testing. However, this movement was not clinically significant in vivo during magnetic resonance imaging (MRI).
Area of Science:
- Biomaterials Science
- Medical Imaging
- Otolaryngology
Background:
- Middle ear prostheses are used to restore hearing.
- Nonmagnetic, MR-compatible prostheses are preferred for patients undergoing MRI.
- Ex vivo studies suggest potential displacement of these prostheses in high magnetic fields.
Purpose of the Study:
- To evaluate the magnetic field interactions of middle ear prostheses.
- To determine the clinical significance of prosthesis displacement during MRI.
Main Methods:
- Tested prostheses made from 316L stainless steel, platinum, and 420F stainless steel at 4.7 Tesla (T).
- Measured ex vivo translational and rotational motion.
- Assessed in vivo displacement in cadaveric temporal bones using clinical MRI sequences.
Main Results:
- Nonmagnetic stainless steel prostheses exhibited angular deflection ex vivo.
- Platinum controls showed no deflection; ferromagnetic controls deflected >90 degrees.
- In vivo, nonmagnetic stainless steel prostheses remained stable after MRI; ferromagnetic prostheses displaced at 4.7 T but not 1.5 T.
Conclusions:
- Stainless steel middle ear prostheses move ex vivo in high magnetic fields.
- This movement is not clinically significant in vivo at 4.7 T.
- Caution is advised for MRI in patients with strongly ferromagnetic prostheses.