EFFECTS OF MAGNETIC-RESONANCE-IMAGING ON IMPLANTABLE PERMANENT-MAGNETS

Implantable permanent magnets are increasingly used in devices for oto laryngologic applications. It is likely that at least some of the pati ents with implanted magnets will be in need of magnetic resonance imag ing (MRI). The effect of an MRI scan on the magnetic properties of imp lanted permanent magnets has not been previously demonstrated. Some of the basic concepts and descriptive terminology used in industry regar ding permanent magnets are reviewed. Experiments presented show that t he MRI scan is capable of demagnetizing permanent magnets. A case hist ory is also presented that demonstrates demagnetizing of an implanted Audiant magnet by an MRI scan.