Of the otologic implants evaluated for the presence of magnetic field interactions, the McGee stapedectomy piston prosthesis, made from platinum and chromium-nickel alloy stainless steel, is ferromagnetic. The manufacturer has recalled this otologic implant. Patients who received this device have been issued warnings to avoid MR procedures. The specific item and lot numbers of the McGee implants recalled and considered to be a contraindication for MR procedures are as follows (Personal Communication, Winston Geer, Smith & Nephew Richards Inc., Barlett, TN):
Item No. Lot Number:
14-0330 1W91100, 4UO9690
14-0332 1W91110, 4U58540, 4U86300
14-0333 4U09710, 1W34390, 2WR4073
14-0334 4U09720, 1W34390, 2WR4073
14-0335 1W34400, 4U09730
14-0336 3U18350, 3U50470, 4UR2889
14-0337 3U18370, 4UR2889
14-0338 3U18390, 4U02900, 4UR1453
14-0339 3U18400, 3U50500
14-0340 3U18410, 3U50500
14-0341 3U41200, 4UR2889
MR Unsafe Otologic Implants. Besides the above information, there are several other MR Unsafe otologic implants that exist including, the following (Kurz, www.kurzmed.de/en/products/mri-safety/)
- Tuebingen Type Ventilation Tubes with Wire, Gold-Platinum, Stainless Steel
- Tuebingen Type Ventilation Tubes with Wire, Gilded Silver, Stainless steel
- Tuebingen Type Ventilation Tubes with Wire, Pure Titanium, Stainless Steel
- Minimal Type Ventilation Tube, Gold-coated, Stainless Steel
MRI Information at 3-Tesla and Otologic Implants. MRI at 3-Tesla and Otologic Implants. Many otologic implants have been evaluated for magnetic field interactions at 3-Tesla (see The List). In consideration of the relatively small sizes of these items, MRI-related heating is not a concern at 3-Tesla. For the ones tested, all are considered to be acceptable for patients based on findings for translational attraction, torque, and according to the intended in vivo uses of these specific devices.
Otologic Implants, Micromedics, Inc. (Eagan, MN)
MRI testing at 3-Tesla was conducted on the following products from Micromedics, Inc:
Stainless Steel Vent Tube & Stainless Steel Wire
Because of the size of the metallic mass associated with this particular product, the MRI test findings (MR Conditional 6, 3-Tesla or less) apply to all of the products listed below (Micromedics, Inc., Eagan, MN):
VT-0205-, Fluoroplastic with stainless steel wire
VT-0702-, Silicone with stainless steel wire
VT-1402-, Stainless Steel with stainless steel wire
VT-1412-, Titanium with stainless steel wire
VT-1505-, Polyethylene with stainless steel wire
Otologic Implants, Grace Medical (Memphis, TN).
Grace Medical http://www.gracemedical.com/
Magnetic Resonance Imaging (MRI) Information for Grace Medical Otologic Implants
Dear Medical Professional:
MRI may be contraindicated or can pose risks for patients that have certain metallic implants primarily due to substantial magnetic field interactions or excessive MRI-related heating. Therefore, caution is advised when using MRI procedures in patients with metallic implants and devices.
The Otologic device families listed in Table 1 below are considered MR Safe according to the American Society for Testing and Materials (ASTM) International, Designation: F2503 since these items are made from non-metallic and non conducting materials.
The Otologic device families listed in Table 2 below are considered MR Conditional according to the American Society for Testing and Materials (ASTM) International, Designation: F2503 and based on MRI tests conducted on selected implants that represented worst case with regard to materials and mass.
The MRI Information is, as follows:
Non-clinical testing has demonstrated that patients with these specific Grace Medical otologic implants can undergo MRI safely, immediately after implantation under the following conditions:
• Static magnetic field of 3-Tesla or less
• Maximum spatial gradient magnetic field of 720-Gauss/cm or less.
• MR system reported, whole-body-averaged specific absorption rate (SAR) of 2.9 –W/kg for 15 minutes of scanning (i.e., per pulse sequence).
Under controlled testing conditions a temperature rise equal to or less than +1.6-degrees C occurred.
MR image quality may be compromised if the area of interest is in the exact same area or relatively close to the device. Therefore, optimization of imaging parameters may be necessary.
All Grace Medical otologic implants that are considered MR Conditional have been packaged with an MRI Patient Card.
Should you have any questions regarding a specific implant, or if an implant is not in one of the tables below, please contact Grace Medical at 1-866-472-2363.
Table 1. MR Safe
Device Family, Stapes Prostheses-Pistons; Family Product Number(s), 401-XXX, 402-XXX, 403-XXX, 404-XXX, 405-XXX, 406-XXX, 408-XXX; Device Material(s), Fluoroplastic
Device Family, Partial and Total Prostheses; Family Product Number(s),1XX, 190-XXX; Device Material(s), HA, hydroxyapatite
Device Family, Partial and Total Prostheses; Family Product Number(s),2XX, 193; Device Material(s), HA (hydroxyapatite), Silicone
Table 2. MR Conditional
Device Family, ALTO Partial and Total Prosthesis; Family Product Number(s), 6XX; Device Material(s), Titanium, HA (hydroxyapatite), Silicone
Device Family, K-Helix Prosthesis; Family Product Number(s), 756-XXX, 757-XXX; Device Material(s), Titanium
Device Family, Strasnick Prosthesis; Family Product Number(s), 220-XXX, 270-XXX; Device Material(s), Titanium, Silicone
Device Family, Precise Prosthesis; Family Product Number(s), 700-XXX, 705-XXX, 720-XXX, 750-XXX, 765-XXX, 770-XXX; Device Material(s),Titanium, HA (hydroxyapatite)
Device Family, Stapes Prosthesis, Piston; Family Product Number(s), 409-XXX, 410-XXX, 411-XXX, 412-XXX, 413-XXX, 415-XXX, 417-XXX, 418-XXX, 419-XXX, 452-XXX, 453-XXX, 465-XXX, 466-XXX, 467-XXX, 468-XXX, 469-XXX; Device Material(s), Titanium, Platinum, Stainless Steel, Nitinol, Fluroplastic
Device Family, Stapes Prosthesis, Bucket; Family Product Number(s), 420-XXX, 421-XXX, 422-XXX, 423-XXX, 424-XXX, 425-XXX, 426-XXX, 427-XXX, 428-XXX, 429-XXX, 430-XXX; Device Material(s), Titanium, Nitinol
Grace Medical, http://www.gracemedical.com/
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