BAHA Devices and Magnetic Resonance Imaging Scanners

Hypothesis: That an osteointegrated Bone-anchored Hearing Aid (BAHA System) will show movement or displacement when exposed to a 9.4-T magnetic resonance imaging (MRI) magnet and that any movement may have implications for patient safety and image quality. Background: BAHA System implanted patients may require MRI scans for various pathologies. The possibility of BAHA fixture and abutment movement can be explored to help clarify patients' and physicians' decisions regarding safety issues. Setting: University Medical Center (tertiary care center). Methods: BAHA System assembled fixture with abutment of 3 and 4 mm were each placed inside of a Petri dish and mounted into human cadaver temporal bones, then exposed to a 9.4-T MRI magnet. The BAHA System external processor was entered into the MRI suite. Head MRI images and charts of 2 patients with BAHA System devices who had undergone MRI scanning at 1.5 and 3.0 T, respectively, were reviewed. Results: The BAHA System fixture with abutment moved inside of the Petri dish. The temporal bone studies revealed no sign of motion or displacement. The external BAHA processor showed strong movement toward the magnet. MRI scannings of patients were without any adverse effects. Image MRI quality was affected only around the BAHA post. Conclusion: The bone-mounted fixture with abutment of 3 and 4 mm resisted any magnetic forces trying to displace them up to 9.4 T. Two patients underwent scanning at 1.5 and 3.0 T with no adverse effects. MRI image quality was excellent starting at 1 cm from the fixture with abutment. The study findings lend strong evidence that patients can be safely scanned up to 9.4 T without adverse effects.