Demagnetization of cochlear implants and temperature changes in 3.0T MRI environment
This paper was presented at the 11th International Conference on Cochlear Implants in Children, Chapel Hill, NC, April 11-14.
Received 17 June 2008; received in revised form 21 July 2008; accepted 21 July 2008.
Objective
To investigate the level of demagnetization of the magnets and temperature changes in cochlear implants (Cis) in a 3.0 tesla (3.0T) MRI.
Study Design
Experimental.
Subjects and Methods
Demagnetization and remagnetization measurements were done on magnets for different types of CIs. Temperature of different body and electrode sides was measured in the MRI environment.
Results
Demagnetization of the magnets of the CI is dependent on the angle between the magnetic field of the CI magnet and the MRI. When this angle was greater than 80 degrees, relevant demagnetization occurred and sufficient remagnetization was not possible with the 3.0T MRI magnet. Maximum temperature rise was 0.5°C.
Conclusions
Patients carrying CIs with non-removable magnets should not enter a 3.0T MRI device in a routine clinical setup. Under special conditions (angle between the two magnets less than 80 degrees) imaging in a 3.0T MRI may be possible without harming the patient or the implant.
aMedical University of Hannover, Clinic for Otolaryngology, Hannover, Germany
bInternational Neuroscience Institute, Department of Neurosurgery, Hannover, Germany
cR&D Department, MED-EL Elektromedizinische Geraete GmbH, Innsbruck, Austria
dVanderbilt University Medical Center, Clinic for Otolaryngology, Nashville, TN
Corresponding author: Omid Majdani, MD, PhD, Department of Otolaryngology–Head and Neck Surgery, Vanderbilt University Medical Center, Suite 7209 Medical Center East, Nashville, TN 372332
Medical University of Hannover, Otolaryngology Head and Neck Surgery, Carl-Neuberg-Str 1, OE 6500, 30625 Hannover, Germany.
ABSTRACT