[Behaviour of titanium middle ear implants at 1.5 and 3 Tesla field strength in magnetic resonance imaging].
BACKGROUND
Investigations into the MRI compatibility of middle ear implants made from titanium alloys with 1.5 and 3.0 tesla MRI systems which are frequently used for imaging diagnostics.


METHODS
17 different middle ear (ME) implants (ossicular replacement prosthesis (ORP) and ventilation tubes) made from titanium were tested in vitro. Potential warming was determined via an MRI-compatible fibre optic temperature sensor under the influence of sequences with high-level high frequency impulses. An assessment of the attractive force of the implants was carried out placed on a Petri dish under vibration and floating on rubber-sponge (RS) in a water bath.


RESULTS
No significant warming of the implants was observed with any of the used sequences at either 3 or 1.5 Tesla field strength (TF). With 3 TF, all 17 implants changed their position on the surface of the water and moved at a slow speed (0.0004-0.0014 m/s) towards the magnetic field. With 1.5 TF, the tested ME implants moved at a maximum speed of 0.0002 m/s and in the case of the ventilation tubes at 0.0005 m/s.


CONCLUSIONS
No warming occurred in any of the tested middle ear implants at either 1.5 or 3 TF. The attractive forces exerted through the static magnetic field were overall low at 1.5 and 3 TF, indicating that no dislocation is to be expected if intraoperative anchoring is correctly conducted. Nevertheless, the indication for examination at 3 TF should be carefully considered due to the anatomically sensitive region.
Bauknecht
H C
HC
Abteilung Neuroradiologie, Institut für Radiologie, Charité Universitätsmedizin Berlin, Berlin. christian.bauknecht@charite.de
Jach
C
C
Krug
L
L
Schrom
T
T
D000075202:Contraindications; D004574:Electromagnetic Fields / Q000009:adverse effects; D019544:Equipment Failure Analysis; D004869:Equipment Safety; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008876:Middle Ear Ventilation / Q000295:instrumentation*; D009998:Ossicular Prosthesis; D013696:Temperature; D014025:Titanium
D014025:Titanium