Safe magnetic resonance scanning of patients with metallic middle ear implants.

摘要

OBJECTIVE: To determine the MR scanning risk to patients with otologic implants. DESIGN: We used a repeated-measures study with an additional control measure to assess two aspects of risk; (i) movement of the device in the magnetic field, and (ii) absorption of energy leading to local heating. We used an ex vivo test method that met with international standards. We measured the effects in a Philips Intera Achieva 3 Tesla (T) MR scanner using a Sense Head 8 channel RF coil. SETTING: University-based magnetic resonance research facility. MAIN OUTCOME MEASURES: Heating or displacement of the stapedectomy pistons. RESULTS: No evidence of displacement or heating was found. CONCLUSION: Complying with the ex vivo standard testing protocols, the Schuknecht and McGee wire pistons (device product numbers 140106 and 140108, respectively) were found to be safe in a 3 T MR scanner. These conclusions can be extrapolated to the in vivo case.