Magnetic resonance imaging compatibility testing of the clarion 1.2 cochlear implant

Objective: This study aimed to investigate the compatibility of the Clarion 1.2 magnet-containing cochlear implant with a 1.5-tesla (T) and 0.3-T magn etic resonance imager. Background: Cochlear implants restore functional hearing to patients with s ensorineural deafness. With the rapidly increasing number of patients with cochlear implants, there is a need to investigate the implant's magnetic re sonance imaging (MRI) compatibility. Methods: The authors tested the potential torque and force on the metallic components of the implant, heating of the implant and surrounding tissue, u nintentional output, implant damage, and image distortion. Tests were perfo rmed in both a 1.5-T and 0.3-T MRI. Results: The torque experienced by the implant in the 1.5-T MRI (0.19 nm) w as large enough that it could potentially cause implant movement in some pa tients. An acceptable amount of torque (0.04 nm) was found in the 0.3-T MRL . Image distortion occurred in the area directly around the implant with a radius of up to 60 mm in the 1.5-T MRI and 100 mm in the 0.3-T MRI. In both MRI units, there was no detectable temperature increase or unintentional o utput. There was no implant damage except that with worst-case conditions, the internal magnet was demagnetized by 78.5% with the 1.5-T unit and 3.36% with the 0.3-T unit. Conclusions: The authors recommend patients with cochlear implants avoid im aging in a 1.5-T MRI. The results suggest that the 0.3-T MRI poses little o r no risks to patients with cochlear implants.