MRI Machines May Damage Cochlear Implants

Main Category: MRI / PET / Ultrasound
Also Included In: Hearing / Deafness;  Ear, Nose and Throat
Article Date: 01 Dec 2008 - 3:00 PST

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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, according to new research published in the December 2008 issue of Otolaryngology - Head and Neck Surgery.

A cochlear implant is an electronic device that restores partial hearing to the deaf. It is surgically implanted in the inner ear and activated by a device worn outside the ear. Unlike a hearing aid, it does not make sound louder or clearer. 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.

The study, conducted by a team of German and American researchers, tested several cochlear device magnets on a 3T MRI scanner with active shielding at a variety of angles (0º, 80º, 90º, 100º, 110º, and 180º). The researchers discovered that during routine use of 3T MRI machines at angles above 80º, an unacceptable level of demagnetization was reached, causing permanent damage to devices with non-removable magnets, and creating the potential of exposing patients to undesirable magnetic forces.

3T MRI scanners are the next generation of MRI scanners and are significantly more powerful than 1.5T MRI scanners.

As a result 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.

Notes:

Otolaryngology - Head and Neck Surgery is the official scientific journal of the American Academy of Otolaryngology - Head and Neck Surgery Foundation (AAO-HNSF) and the American Academy of Otolaryngic Allergy (AAOA). The study's authors are Omid Majdani, MD, PhD; Martin Leinung, MD, PhD; Thomas Rau; Arash Akbarian, MD, PhD; Martin Zimmerling, PhD; Minoo Lenarz, MD, PhD; Thomas Lenarz, MD, PhD; and Robert Labadie, MD, PhD.

About the AAO-HNS

The American Academy of Otolaryngology - Head and Neck Surgery (http://www.entnet.org), one of the oldest medical associations in the nation, represents nearly 12,000 physicians and allied health professionals who specialize in the diagnosis and treatment of disorders of the ears, nose, throat, and related structures of the head and neck. The Academy serves its members by facilitating the advancement of the science and art of medicine related to otolaryngology and by representing the specialty in governmental and socioeconomic issues. The organization's vision: "Empowering otolaryngologist-head and neck surgeons to deliver the best patient care."

Source:
Jessica Mikulski
American Academy of Otolaryngology -- Head and Neck Surgery