In vitro magnetic resonance imaging evaluation of ossicular implants at 3 T.
OBJECTIVE
Ossicular implants made from metallic materials may be acceptable or pose hazards for patients referred for magnetic resonance imaging (MRI) examinations, depending on the outcome of proper MRI testing procedures.


BACKGROUND
Using a 3-T MR system, 2 ossicular implants were tested for magnetic field interactions, heating, and artifacts.


METHODS
Two different ossicular implants (Stainless Steel/Fluoroplastic Sanna-Type Piston [6 mm in length] and the Offset ALTO Total Prosthesis [15 mm in length, titanium/silicone]; Grace Medical, Memphis, TN, USA) were selected for testing, which represented the largest metallic mass and materials with the highest magnetic susceptibilities, with the intent of applying the MRI findings to other ossicular implants. The implants were evaluated at 3-T for magnetic field interactions, heating, and artifacts using standard previously described techniques.


RESULTS
Each ossicular implant showed relatively minor magnetic field interactions that will not be associated with movement in situ. Heating was not excessive (highest temperature change, ≤ 1.6°C; background temperature change, 1.5°C). Artifacts, although relatively small, may create issues for diagnostic imaging if the area of interest is in the same area or close to these ossicular implants.


CONCLUSIONS
The results of this investigation demonstrated that it would be acceptable (i.e., "MR conditional" using current terminology) for patients with these ossicular implants to undergo MRI examinations at 3 T or less. In consideration of the materials and dimensions of the implants that underwent testing, these findings pertain to many other similar ossicular implants from the same manufacturer.
Keck School of Medicine, University of Southern California and Institute for Magnetic Resonance Safety, Education, and Research, Los Angeles, California 90045, USA. frank.shellock@gte.net
Frank G
FG
Shellock
Lauren N
LN
Meepos
Matthew R
MR
Stapleton
Sam
S
Valencerina
D016477:Artifacts; D004869:Equipment Safety; D006801:Humans; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods; D009998:Ossicular Prosthesis