MRI scanners and the stapes prosthesis

Objective: Physicians and patients alike have concerns regarding exposing in vivo implanted metal stapes prostheses to magnetic resonance imaging (MRI) scanners. As MRI scanners become more powerful, the possibility for stapes prosthesis displacement due to ferromagnetic forces increases. It is hypothesized that some metal stapes prostheses may be exposed to powerful MRI scanners without leading to potential adversities for patients. Study Design: Literature review, retrospective case review, and physician survey. Settings: Tertiary care, University Medical Center. Materials and Methods: A review of the medical literature, a retrospective case review, and a clinical survey were performed. Results: In the history of stapes prostheses, I adverse patient outcome was causally substantiated when a defective stapes prosthesis was exposed to an MRI field. Otherwise, a review of the literature on experiments investigating stapes prostheses and MRI fields revealed a lack of any adverse clinical reports. In addition, 2 physician's surveys revealed no other cases of symptoms or damage to the ears of patients with stapes prostheses that had been exposed to an MRI scanner. Conclusion: All patients with a metallic stapes prosthesis may be sent to the MRI scanner, with the exception of I specific defective prosthesis type. The exception is a 1987 accidental mismanufacture of several lots of McGee pistons with a magnetic alloy. Patients with these specifically identified lots of McGee pistons should go to a computed tomographic scanner or be reimplanted with another prosthesis if MRI scans are mandatory. It would be advisable for manufacturers to use nonferromagnetic metals such as titanium for production of future stapes prostheses.