3.0T with the magnet removed
The internal magnet must be removed. See the “Surgeon Manual for the HiRes Ultra Cochlear Implant” for removal instructions.
The external sound processor and headpiece are MR Unsafe and must be removed before entering a room containing an MR scanner.
Horizontal closed bore scanners with a static magnetic field of 3.0T
Maximum spatial field gradient of 2,000 Gauss/cm (20 T/m)
Maximum MR system reported, whole body averaged specific absorption rate (SAR) of ≤ 2.0 W/kg at 3.0T (Normal Operating Mode) for quadrature transmit RF body coils
Maximum MR system reported, head averaged SAR of ≤ 2.6 W/kg at 3.0T (Normal Operating Mode) for quadrature transmit RF head coils
RMS gradient field of 30 T/s and peak gradient field of 150 T/s
Under the scan conditions defined above the HiRes Ultra implant is expected to produce a maximum temperature rise of <3°C after 15 minutes of continuous 3.0T scanning.
In MRI testing of unilateral and bilateral recipient conditions, respectively, the image artifact caused by the device extends from the HiRes Ultra implant approximately 5 cm using a spin echo pulse sequence in a 3.0T scanner with the temporary non-magnetic plug in place. These artifacts may result in a loss of diagnostic information in the implant vicinity.
The recommended minimum duration of time post implant surgery prior to undergoing an MRI scan is 2 to 4 weeks in order to allow any inflammation to subside.
An MRI scan is not recommended if the patient has a fever.