People with cochlear implants should avoid undergoing scans via magnetic imaging devices, such as 3T MRI machines, because scientists have now found that the machines can demagnetize the patients implant.
According to the new research published in the December 2008 issue of Otolaryngology – Head and Neck Surgery, Patients with cochlear implants may want to steer clear of certain magnetic imaging devices, such as 3T MRI machines, because the machines can demagnetize the patient’s implant. 3T MRI scanners are the next generation of MRI scanners and are significantly more powerful than 1.5T MRI scanners.
A cochlear implant is a surgically implanted electronic device in the inner ear and activated by a device worn outside the ear. The device restores partial hearing to the deaf. It provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. Instead, the device bypasses damaged parts of the auditory system and directly stimulates the nerve of hearing, allowing individuals who are profoundly hearing impaired to receive sound. It is estimated that more than 100,000 people have cochlear implants.
Cochlear implants also contain internal magnets used to connect an external processor with the surgically implanted components, Dr. Omid Majdani, of the Medical University of Hannover, Germany, and colleagues explain. These magnets can interact with other magnets, such as those found in magnetic resonance imaging (MRI) machines. MRIs exert strong magnetic fields that may induce voltages or temperatures that could damage the implant or harm the patient. The researchers examined the extent of damage to the magnets and the temperature changes in cochlear implants exposed to an MRI machine.
The team of German and American researchers who conducted the study tested several cochlear devices on a 3T MRI scanner with active protecting at a variety of angles (0º, 80º, 90º, 100º, 110º, and 180º). The maximum temperature increase in the cochlear implants was 0.5 degrees C, within the acceptable limit of 1.0 degrees in any location. The researchers discovered that use of 3T MRI machines at angles above 80º during routine, an unacceptable level of demagnetization was reached, causing permanent damage to devices with non-removable magnets and creating the potential of exposing patients to unwanted magnetic forces.
Based on the final results of their findings, the study authors recommend that MRI scans on patients with cochlear implants should be performed using a 3T MRI machine only if a 1.5T machine is not available, and if the benefits of the scan far outweigh the risk of cochlear implant demagnetization.