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One of the most common risks of MRI scanning is the risk of thermal injury. Burns can result when any object containing metallic or ferromagnetic material superheats during the scan. While most burns have occurred due to things like superficial EKG electrodes or coils, the risk of thermal injury has also been attributed to some unusual items: transdermal skin patches, tattoos, tags on breast implants, ingested toy magnets, and even metallic eyelashes (see our previous columns for April 2, 2019 Unexpected Events During MRI and September 2019 New MRI Hazard: Magnetic Eyelashes).
Now the FDA has issued a warning after receiving a report of a patient suffering facial burns from a face mask during MRI FDA 2020. That patient was wearing a face mask with metal during a 3-Tesla MRI scan of the neck. The report described the burns to the patients face being consistent with the shape of the face mask.
Some face masks and respirators contain metal parts or coatings. The FDA notes that metal parts, like nose pieces nose clips or wires, headband staples, nanoparticles (ultrafine particles), or antimicrobial coating that may contain metal (such as silver or copper), may become hot and burn the patient during an MRI.
The FDA acknowledges that it may be appropriate for a patient to wear a face mask during an MRI exam, especially during the COVID-19 pandemic. But it is critical to ensure the face mask contains no metal.
FDA recommends that, if the absence of metal cannot be confirmed and it is determined to be appropriate for the patient to wear a face mask, an alternative face mask where the absence of metal can be confirmed should be used. Health care providers who perform MRI exams are encouraged to provide face masks without metal to patients who will undergo an MRI.
Your pre-MRI checklist, of course, includes screening for metallic objects. Looking at the face mask could identify obvious metallic parts, like nose pieces or staples, but wont reveal things like nanoparticles or coatings mentioned in the FDA warning. The FDA warning does not mention whether metal detection devices can detect some of those less obvious items.
So, our recommendation would be to not allow patients to wear their own face masks during MRI. Instead, each facility should provide them with a face mask known to be free of those metallic components.
That recommendation is echoed by Tobias Gilk, an MRI safety expert whom we have cited in many of our columns (Yee 2020). "The staples holding the elastic to the mask are too small to conduct heat, and since the COVID-19 pandemic, patients have been imaged in masks that have nose bridges without injury," he said. "But antimicrobial treated fabric can heat up. So, to be safe, patients should be provided with disposable surgical masks before their MRI."
And, of course, appropriate infection control procedures need to be followed when handling either the patients own face mask or the one provided by the facility.
Lastly, it also makes sense that your own MRI staff must wear face masks known to be free of those metallic components. That would include other hospital staff who might have to respond to an emergency in the MRI suite.
Metallic elements are showing up more and more in places wed never think of looking for.
Some of our prior columns on patient safety issues related to MRI:
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