The Hoffmann 3 is an MR Conditional device. This means patients with this device can be safely scanned in MRI but under certain conditions. The manufacturer conditions are somewhat ambiguous and quite restrictive in regard to the allowable specific absorption rate (SAR) which controls the amount of energy disposition and heating that the patient experiences. While no physical injury has been observed we have now had a number of patients with this device who have stopped their MR scans due to heating.
While we will always aim to scan within the MR Conditions it may not always be possible for the MRI unit to satisfy these conditions and also get the diagnostic quality desired. That being the case we may need to scan a patient with this device ‘off-licence’. We would consider the risk to a patient with this device to be low. The manufacturer places the onus on the radiologist and MR scientist to assess each case on its merits. The latest manufacturer IFU can be opened below, pages
Should you be required to vet or justify MR imaging a patient with this device then the recommendation from the MR Safety Experts is that provided the clinical justification for scanning is good and there is a good reason to scan ’now’ and not wait until the frame has been removed, then the MR scan should proceed. That is, the perceived benefit would outweigh the risk.
Further guidance will be provided to the radiographers in regard assessing the device (to ensure the device is indeed a Hoffmann 3 device) and on how to limit SAR as far as is reasonably practicable whilst still acquiring diagnostic quality images.