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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.
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:
References:
https://www.auntminnie.com/index.aspx?sec=sup&sub=mri&pag=dis&ItemID=131064
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