Cochlear Implants & MRI Compatibility
MRI (Magnetic Resonance Imaging) is a common scan used for a medical imaging procedures. MRI uses a very powerful magnet to provide detailed images of a person’s internal organs and tissue. It is often used to provide early detection of many different conditions so that treatment can be more effective and timely.
As implanted medical devices can interfere with MRI scans, it’s important to consider the compatibility of this increasingly popular technology with your choice of cochlear implant.
How does a cochlear implant affect MRI?
The internal implant contains a magnet, which holds the external sound processor coil in place. When placed in an MRI scanner, this magnet can cause a blur or ‘artifact’ over the medical image, which may hinder the Doctor’s ability to make an accurate diagnosis of brain scans. As a quarter of all MRI scans are performed on the brain, having the flexibility to remove the internal magnet if required is an important consideration when choosing a cochlear implant.
A 1.5 Tesla MRI scan of a Nucleus® implant recipient with the magnet in place. The yellow line represents implant placement. The implant magnet creates a large blur on the image, hindering an accurate diagnosis.
A 1.5 Tesla MRI scan of a Nucleus implant recipient with magnet removed. The yellow line represents implant placement. The blur on the image is significantly reduced and causes minimal interference with the diagnosis2. (Images courtesy of Royal North Shore Radiology (Sydney, Australia)).
Other brands may not feature a removable magnet
This means that recipients may be limited by older MRI technology or may need their entire implant including the electrode removed, even for a scan of a different part of the body such as the knee.
Implant removal requires surgery. Once an implant is removed, it cannot be re-used, meaning a new implant is required and therefore further surgery.
Why is compatibility with high strength MRI so important?
1.5 Tesla strength MRIs are considered standard at present, however 3.0 Tesla scans are becoming increasingly popular due to their superior image quality. With the continuing trend towards higher strength MRIs, the compatibility of cochlear implants with MRI is an important lifetime decision.
Why MRI over X-ray or other types of imaging devices?
There are a variety of imaging techniques available to obtain images of the body such as X-rays, CT scans, PET scans and ultrasounds. Different techniques are required for different reasons. MRI is becoming increasingly popular thanks to its ability to capture detailed images of soft tissue and joints, plus its ability to diagnose other conditions such as heart disease and cancer. Additionally, MRI does not use radiation such as other techniques like X-ray, making it a safer option.
Do all cochlear implants have the same MRI compatibility?
No. MRI compatibility differs between cochlear implant manufacturers. Nucleus implants from Cochlear are approved for MRI scans at 1.5 Tesla with the internal magnet in place and 3.0 Tesla with the magnet removed3. No other implant manufacturer can offer this level of MRI compatibility.
How does the removal procedure work?
The magnet can be removed in a simple outpatient procedure before the MRI takes place. A temporary fixing disc is then used to hold the external coil in place, meaning that the recipient only experiences hearing downtime during the actual scan, when the sound processor cannot be worn. Once the MRI is complete, a sterile magnet is re-inserted into the implant.
The magnetic field used in MRI can cause a weakening of the internal magnet in any cochlear Implant. As a result, the sound processor coil may not remain firmly in place. The ability to replace the internal magnet resolves this issue, and prevents having to have a device explanted and a new cochlear implant re-implanted.
Please seek advice from your medical practitioner or health professional about treatments for hearing loss. They will be able to advise on a suitable solution for the hearing loss condition. All products should be used only as directed by your medical practitioner or health professional.
Not all products are available in all countries. Please contact your local Cochlear representative.
- Risi F. Saldanha A, Leigh R, Gibson R. Magnetic resonance imaging safety of Nucleus 24 cochlear implants at 3.0 T. International Congress Series; 1273 (2004) 394–398.
- MRI compatibility varies by country depending on regulatory approvals in each country. Please check the MRI guidance provided in your country by contacting your local cochlear representative or clinic before proceeding with an MRI scan.