Magnetic Resonance Imaging of Cochlear Implant Recipients

Objective: Determine the diagnostic usefulness of postimplantation 1.5 T magnetic resonance imaging (MRI) and review magnet-related MRI complications. Study Design: Retrospective chart review with additional review of MRIs. Setting: Tertiary care children's hospital. Patients: Twelve patients who underwent MRI after receiving a cochlear implant (CI). Intervention: One or more episodes of 1.5 T MRI with CI in place. Main Outcome Measures: Occurrence of magnet-related complications; whether imaging was clinically useful. Results: The 12 patients underwent 23 episodes of MRI, including 13 episodes in 11 patients (18 ears) during which a magnet was present and 17 studies were obtained. Complications related to the magnet occurred during 4 of the 13 imaging episodes (30.8%), all during body or spine studies. Magnet torsion with reversal of polarity occurred in three devices; reduced magnet strength in one; and displacement of the magnet from its housing in one. One patient required surgical magnet replacement, whereas other headpiece retention problems were resolved without surgery. All studies but one brain with bilateral magnets were clinically useful. Conclusions: CI patients who undergo MRI with a magnet in situ may experience complications, especially when imaged below the head. Most complications may be resolved without surgery. Diagnostic usefulness of non-cranial MRI is not likely to be limited by presence of the magnet, while a magnet may prevent clinically useful brain imaging. Obtaining MRI with the magnet in situ avoids the cost and risks associated with multiple surgeries to remove and replace the magnet or the entire implant.