[Factors for Degaussing of a Cochlear Implant Magnet in the MR Scanner]

Area of Science:

• Medical Imaging
• Biomagnetism

Background:

• Magnetic Resonance Imaging (MRI) is crucial for diagnostics.
• Cochlear implant magnets can be affected by MRI's static magnetic fields.
• Understanding magnet degaussing is vital for patient safety and device function.

Purpose of the Study:

• To investigate factors influencing magnet degaussing within an MRI environment.
• To determine the impact of magnet orientation and movement on degaussing rates.
• To provide guidance for MRI procedures involving patients with cochlear implants.

Main Methods:

• Magnets were secured using Poly methyl methacrylate (PMMA) at varying angles (0°-180°) relative to the MRI's static magnetic field.
• PMMA was moved within the MRI magnetic field to simulate conditions.
• Magnetic flux density was measured pre- and post-movement to calculate degauss rate.
• Statistical analysis was performed using the Mann-Whitney U test.

Main Results:

• The angle between the measurement magnet's flux vector and the static magnetic field significantly influenced degaussing.
• Other tested factors included number of movements, velocity, and spatial magnetic field gradients.
• The orientation of the magnetic flux vector was identified as the most critical factor for degaussing.

Conclusions:

• Magnet orientation is a primary factor affecting degaussing in MRI scans.
• MRI operators must identify the magnetic flux vector directions of cochlear implant magnets.
• This knowledge is essential for safe MRI examinations of patients with cochlear implants.