TY - JOUR
T1 - Middle ear prosthesis displacement in high-strength magnetic fields
AU - Williams, Michelle D.
AU - Antonelli, Patrick J.
AU - Williams, Lorna Sohn
AU - Moorhead, Jacquelyn E.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2001
Y1 - 2001
N2 - Hypothesis: Middle ear prostheses made from nonmagnetic, magnetic resonance (MR)-compatible metals reportedly displace ex vivo in the presence of high magnetic fields used in MR imaging (MRI). The authors postulate that the prosthesis displacement seen with "nonmagnetic" MR-compatible prostheses ex vivo may not be clinically significant in vivo. Methods: Middle ear prostheses made from ferromagnetic (420F stainless steel) and nonmagnetic MR-compatible metals (316L stainless steel and platinum) were examined for magnetic field interactions at 4.7 Tesla (T). Ex vivo testing consisted of measurements of the translational and rotational motion of the prosthesis induced by the static magnetic field. In vivo testing was assessed by implanting prostheses in cadaveric temporal bones and performing clinical MRI sequences. Prosthesis displacement was measured semiquantitatively. Results: Angular deflection was observed in all samples made from nonmagnetic stainless steel. The negative control (platinum) demonstrated no deflection, and the positive controls (ferromagnetic stainless steel) deflected >90°. Torque analysis showed movement in five of five nonmagnetic stainless steel prostheses. Prostheses made from nonmagnetic stainless steel remained in place without appreciable loosening in vivo after MRI. Prostheses made with known ferromagnetic properties were displaced at 4.7 T but not at 1.5 T. Conclusion: Middle ear prostheses made from low-magnetic stainless steel do move in the presence of high magnetic fields ex vivo; however, this does not appear to be clinically or statistically significant in vivo at 4.7 T. Magnetic resonance imaging should be undertaken with caution in individuals with prostheses made from stainless steel with strong ferromagnetic properties.
AB - Hypothesis: Middle ear prostheses made from nonmagnetic, magnetic resonance (MR)-compatible metals reportedly displace ex vivo in the presence of high magnetic fields used in MR imaging (MRI). The authors postulate that the prosthesis displacement seen with "nonmagnetic" MR-compatible prostheses ex vivo may not be clinically significant in vivo. Methods: Middle ear prostheses made from ferromagnetic (420F stainless steel) and nonmagnetic MR-compatible metals (316L stainless steel and platinum) were examined for magnetic field interactions at 4.7 Tesla (T). Ex vivo testing consisted of measurements of the translational and rotational motion of the prosthesis induced by the static magnetic field. In vivo testing was assessed by implanting prostheses in cadaveric temporal bones and performing clinical MRI sequences. Prosthesis displacement was measured semiquantitatively. Results: Angular deflection was observed in all samples made from nonmagnetic stainless steel. The negative control (platinum) demonstrated no deflection, and the positive controls (ferromagnetic stainless steel) deflected >90°. Torque analysis showed movement in five of five nonmagnetic stainless steel prostheses. Prostheses made from nonmagnetic stainless steel remained in place without appreciable loosening in vivo after MRI. Prostheses made with known ferromagnetic properties were displaced at 4.7 T but not at 1.5 T. Conclusion: Middle ear prostheses made from low-magnetic stainless steel do move in the presence of high magnetic fields ex vivo; however, this does not appear to be clinically or statistically significant in vivo at 4.7 T. Magnetic resonance imaging should be undertaken with caution in individuals with prostheses made from stainless steel with strong ferromagnetic properties.
KW - Magnetic fields
KW - Magnetic resonance imaging
KW - Middle ear prosthesis
KW - Safety
KW - Stapes prosthesis
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U2 - 10.1097/00129492-200103000-00007
DO - 10.1097/00129492-200103000-00007
M3 - Article
C2 - 11300262
AN - SCOPUS:0035078808
SN - 1531-7129
VL - 22
SP - 158
EP - 161
JO - Otology and Neurotology
JF - Otology and Neurotology
IS - 2
ER -