MRI Examination Guide For Nurotron Cochlear Implant
MRI Safety Information
Nurotron cochlear implant CS-10A is MR Conditional. Before MRI examination, the patient should clearly inform Nurotron of which MRI examination is to be performed. You can contact local Nurotron staff or Nurotron clinical personnel through customer service hotline 400-6333571. Visit www.nurotron.com/MRIWarning for current MRI conditional labelling. Before MRI, the patients should see their implantation surgeon to make sure they are safe to take MRI examination.
processors and accessories are MR Unsafe. Patient should remove them before
entering MRI room.
All external processors and accessories are MR Unsafe. Patient should remove them before entering MRI room.
1.5T MRI can be done with implant magnet in position if Nurotron’s MRI examination guide is followed. For 3.0T MRI, implant magnet should be removed by a qualified surgeon. During MRI, theimplant magnet may move from its normal position if not properly bonded; themagnet strength may change; Patients may feel discomfort or pain when magnetpress against skin. The magnet and the metallic shell of implant can causeartifact.
Guide For Radiologist
1. The preparation before MRI examination
Theradiologist should be aware of the following information before performing MRIon the patient.
1) The implant magnet is required to beremoved under MRI examinations over 1.5T. Under MRI examination equal to orless than 1.5T, the magnet is not required to be removed, but it is required tobe elastically bandaged with an elastic bandage and an elastic plastic piece toprevent shifting (See the 1.5T MRI examination for details).
2) Before the examination, take caution to wait the swelling caused bythe implantation surgery reduced, and for most patients it takes two to fourweeks. Whether the patient takes out the magnet for MRI examination or not, themetal case may cause shadows around the implant. Please inform the patientbeforehand.
2. Patients’ comfort
Please explain to the patient as follows.
1) Compression bandages (for MRI over 0.2T) may prevent the implantmagnet from twisting and shifting, but the patient may still feel pressure.This sensation is similar to the feeling of pressing the thumb against theskin, which does not damage the implant or harm the patient.
2) If the patient feels uncomfortable or feels too tight, remove thepatient from the magnetic resonance machine and consider 0.2T MRI examination(no bandage required). Or consult the patient's attending physician todetermine if the magnet should be removed or using local anesthesia to reducediscomfort.
3. MRI examination kit
When performing 1.5T MRI examination, an MRI examination kit isrequired. The MRI examination kit includes thefollowing:
1) Plastic piece: used to cover the magnetof the implant coil, size: 80*50*1.5mm (Fig. 1 is the plastic piece for MRI examination).
Figure 1. Front and back sides of plastic pieces (Translation ofprinted scripts as follows)
Front Side:Plastic piece for MRI Examination
◊ Before the examination, the patient should clearly inform Nurotronof which MRI examination is to be performed. You can contact Nurotron localstaff or Nurotron clinical personnel through customer service hotline 400-6333571.
◊ The implant magnet is required to be removed under MRI examinationsover 1.5T.
◊ The magnet should be in the center of the bandage and the plastic piece.The medical bandage must be completely wrapped with plastic piece.
◊ Bandaging:Firmly tighten the bandage to its elastic limit, stretch it for at least fourturns around the head, and make sure that the four turns stick together.
◊ Usemedical tape around the center of the elastic bandage to ensure that the tapeis tightly attached to the elastic bandage.
◊ SeeMRI examination of Nurotron Cochlear Implant guide for details.
2) Elastic bandage: used to fix theplastic piece. It is recommended to use elastic bandage with a width of morethan 10cm (as shown in Figure 2).
Figure 2. Example of elastic bandage
3) Medicaltape: used to fix elastic bandage and plastic piece.
4. 1.5T MRI Examination
1) Before entering the MRI room, first removethe speech processor and the coil; draw a contour at the scalp of the coil tomark the center of the magnet. If the patient's hair is too dense, shave thehair at the coil to better fix the elastic piece. If the position of the coilis not found, use magnetic material such as a paper clip or the like. However,this magnetic material must be removed before entering the MRI room.
Figure3. The inner magnet position
2) Take out the plastic piece from the MRIexamination kit and place it at the coil position of the implant to make sure themagnet is in the center of the plastic piece. See Figure 4, fix the plasticpiece with medical tape, and then tightly bandage with medical bandage. Makesure that the centerline of the bandage is at the implant position and try to placethe magnet in the exact center of the bandage. The medical bandage must completelycover the plastic piece.
Figure4. The diagram of the fixing of plastic pieceand elastic bandages
3) Bandaging: Firmly tighten the bandage toits elastic limit, stretch it for at least four turns around the head, and makesure that the four turns stick together.
4) Use medical tape around the center ofthe elastic bandage to ensure that the tape is tightly attached to the elasticbandage.
5. After1.5T MRI examination
After the MRI examination, remove the elastic bandage and theplastic piece, and wear the speech processor. After the speech processionturned on, confirm the sound is normal and there is no discomfort to thepatient. If in doubt, contact your surgeon or Nurotron clinical personnel assoon as possible.
6. MRIexamination over 1.5T up to 3.0T
The implant magnet is required to be removed under MRI examinations over1.5T up to 3.0T, and bandage according to above method before examination.
Precautions for implantmagnet removal
1) The implant magnet needs to be removedby a professional doctor.
2) Ifthe patient needs multiple MRI examinations, a sterile non-magnetic metal plugis required to replace the magnet implant in order to prevent fibrous tissuefrom entering the crypt for the inner magnet.
3) Afterthe inner magnet is removed, the patient could wear a device such as soft beltto fix the coil of the speech processor between multiple MRI examinations.
4) WhenMRI is no longer required, the sterile non-magnetic metal plug should beremoved and a new sterile internal magnet implanted.
The removal of the implant magnet —surgeon guide
Perform systemic or local anesthesiaand remove the magnet under aseptic conditions:
Figure5 Incision on the side of implant Figure 6 Incision of the implant with magnetremoved
1. Make a small incisionto make sure the magnet can be reached. The incision must be on the side of theimplant (do not exceed the coil), see Figure 5.
2.Cut along the fiber growth site aroundthe implant to expose the magnet.
3.Using separator or similar device, carefully lift the top of the siliconeelastic crypt around the magnet and remove the magnet from the implant. Ifthere are residual sutures around the magnet, remove the suture. See Figure 6.
The procedure will vary depending onwhether the patient needs single or multiple MRI examination.
1. Make a small incision to remove the magnet.
2.Leave the magnet crypt empty. Do not close the wound, cover it with a dry andsterile dressing. The crypt can hold up to 4 hours of sterile empty state.
3. Perform theMRI.
4.After the examination, insert a new sterile magnet with the mark “十” (polarity) facing up. Use separatorto raise the hidden lip and place the magnet.
5. Suture the wound layered.
If the patient needs multiple MRI examinations, a sterilenon-magnetic metal plug is required to replace the magnet implant in order toprevent fibrous tissue from growing into the crypt.
Inserta metal plug into the crypt as follows:
1. Makea small incision to remove the magnet. (Figure 6).
2.Use a separator to lift the lip of the crypt and press the non-magnetic metalplug into the place. Be careful not to put too much pressure on the implant.
3. Suture the wound layered.
Whenregular MRI examination is no longer needed:
1.Make a smallincision to expose the magnet crypt.
the non-magnetic metal plug according to the above procedure.
Insert a new sterile magnet with the mark “十”
(polarity) facing up. Use a separator to lift the lip of the crypt and press
the sterile magnet into the place.
4. Suture the wound layered.
3. Insert a new sterile magnet with the mark “十” (polarity) facing up. Use a separator to lift the lip of the crypt and press the sterile magnet into the place.
4. Suture the wound layered.