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Patient Safety Tip of the Week

August 13, 2024

Preventing Thermal Injury During MRI

Though there are many causes of iatrogenic burns (see list below of our prior columns on iatrogenic burns), those related to MR imaging are probably most frequent. Thermal injuries and burns are probably the most common adverse events encountered during MR imaging, accounting for 59% of MRI incidents to the Food and Drug Administration (Delfino 2019). It’s quite likely that thermal injuries related to MR imaging are also underreported.

It's not only the obvious ferromagnetic items that can overheat and lead to burns. But some items are relatively hidden. For example, there may be metal wires or woven metal fibers in face masks and certain clothing items. And transdermal drug patches are often overlooked.

Recently, Baker et al. published a systematic review of the MRI safety literature in relation to radiofrequency thermal injury prevention (Baker 2024). From 98 included studies, they came up with three simplified recommendations:

· Remove any electrically conductive items

· Insulate the patient to prevent any conductive loops or contact with objects

· Communicate regularly

The authors concluded that, by implementing the above recommendations, it is estimated that 97% of skin burns could be prevented. They suggest that assessing individual risks, rather than blanket policies, will help prevent skin thermal injuries occurring, improving patient care.

Their conclusion really is an oversimplification. They actually have many more recommendations.

A primary theme is to remove all unnecessary metallic or electrically conductive items. Baker et al. note that “ferromagnetic detectors (FMDS) are increasingly seen as a tool to be used as an adjunct or ‘final check’ to ensure all ferrous materials have been removed prior to entering the magnet room.” But they note that some materials that are non-ferrous, such as silver, copper and carbon fibre are still electrically conductive and capable of leading to thermal injuries. Even some hair extensions can contain metals that could lead to burns during MR imaging. They go on to describe dangers of various types of jewelry and, as we noted above, transdermal medication patches. They also note that continuous glucose monitoring (CGM) and Flash Glucose Monitoring (Flash GM) for diabetes or health and fitness purposes may be “MR Unsafe” and must be removed prior to scanning. Since many of these devices have a 10-to-14-day use period and cannot be reused once removed, questions about these should be asked at the time of booking and might even influence scheduling the procedure.

A recommendation to change into a gown or pocketless scrubs also avoids other metals potentially fixed to clothing, including fasteners. Baker et al. note it is generally considered that there is minimal risk of burns from small, non-ferrous metallic fasteners such as buttons less than 2 cm. but they can cause artefacts on the images. Our own recommendation is that the hospital gown should be one that has no metal snaps, since disposable gowns that have no metal are readily available. Pocketless scrubs will also remove the risk of unknown items carried in pockets. Baker et al. note that silver and copper are often now used in athletic wear for their antimicrobial properties and even underwear and socks may have these metals. They further note that, while silver and copper are non-ferromagnetic, these materials are excellent electrical conductors and therefore the risk of induced current and subsequent heating does exist.

Another theme is to check the integrity of all equipment. That means identifying any damages or faults, such as cracks and splits in insulation of cables, to ensure unsafe equipment is removed before scanning.

Sometimes, patients may have medically necessary devices or equipment, such as ECG leads or pulse oximetry devices. “MRI conditional” devices usually have adaptions, such as fibre optics, shielding, carbon electrodes and plastic coatings, that ensure the electrically conductive components have reduced risk of burns when used as per manufacturer's instructions. But all ECG and other monitoring equipment associated with the patient should be considered “MR Unsafe” until checked. Only approved “MR Conditional” ECG electrodes and monitoring devices should be applied as per manufacturer’s instructions by MRI trained staff.

Especially important is avoiding formation of any loops between electrically conductive materials, such as ECG leads, coil cables, the scanner bore as well as the patient. These must be separated and insulated from each other.

External fixation devices such as those for lower limbs, halo collars for the cervical spine, and stereotaxic headframes may be “MRI Conditional” but it is important to recognize that these may be electrically conductive and contact with any other wires or cables should be avoided. Individual consideration should be given to potentially electrically conductive materials like surgical staples and RadioFrequency Identification (RFID) and Near Field Communication (NFC) devices.

Use padding to avoid contact burns. They can occur anywhere on the patient but common locations are between the legs, or finger and thigh. These can be exacerbated by sweat and thus prevented by ensuring there is dry, water resistant, non-conductive material as guided by the manufacturer between any skin surfaces that may be in contact.

Baker et al. also warn about tattoos and certain cosmetics as risk factors for burns.

In our April 2, 2019 Patient Safety Tip of the Week “Unexpected Events During MRI” we discussed tattoos, which may be made with color pigments containing ferrous particles that may interact with the magnetic resonance, potentially leading to burns. And our September 2019 What's New in the Patient Safety World column “New MRI Hazard: Magnetic Eyelashes” talked about magnetic eyelashes as a potential risk factor for burns that might be overlooked.

Lastly, monitor and communicate regularly! Baker et al. noted that many superficial burns, such as those associated with tattoos and skin-to-skin contact, are felt instantaneously and the patient can alert the MRI radiographer to uncomfortable sensations right away. MR staff should communicate with their patients about potential risks and the importance of the call bell/buzzer if they have any discomfort. Also, pay attention to any artefacts that appear on early images. These may point to items or materials that could lead to burns. The presence of artefacts should lead to immediate investigation to prevent any burns occurring. And you should seek feedback from patients following their MRI scan to see if any adverse events occurred.

The FDA provides a poster “MRI Burn Prevention” that has the following recommendations:

· Screen patients for implants, devices, and other metallic objects. Assume anything unknown is MR Unsafe.

· Screen objects to ensure that anything entering the scan room is MR Conditional or MR Safe. Match conditions on MR Conditional devices with your scanner. All metals, even non-ferromagnetic ones, have the potential to heat up and cause burns.

· Have patients change out of street clothes whenever possible.

· Position patients to avoid skin-to-skin contact (e.g. no hands on hips, no crossed arms, no crossed legs, etc.)

· Always use the manufacturer-provided padding to insulate the patient. Sheets and blankets may be added for patient comfort but are not a substitute for manufacturer-provided padding.

· Route cables out of the scanner in a straight line. Don’t coil cables or allow them to touch the patient.

· Use only Normal Operating Mode and the lowest SAR, whenever possible.

· Keep your eyes and ears on the patient at all times. Stay in communication with patients to identify warming. Monitor sedated patients using MR Conditional monitoring equipment.

The recently updated ACR Manual on MR Safety also has comments on prevention of burns and thermal injury as part of comprehensive MR safety recommendations.

Our prior columns on iatrogenic burns:

· March 2009 “Risk of Burns during MRI Scans from Transdermal Drug Patches”

· June 1, 2010 “Iatrogenic Burns”

· October 5, 2010 “More Iatrogenic Burns”

· December 23, 2014 “Iatrogenic Burns in the News Again”

· March 2015 “Another Source of Iatrogenic Burns”

· September 5, 2017 “Another Iatrogenic Burn”

· June 5, 2018 “Pennsylvania Patient Safety Authority on Iatrogenic Burns”

· July 28, 2020 “Electrosurgical Safety”

· January 2021 “New MRI Risk: Face Masks”

· May 3, 2022 “Iatrogenic Burns Again”

· December 6, 2022 “Rare Risk – Defibrillator Fires”

· April 25, 2023 “Joint Commission: Beware Light Source Burns”

· December 5, 2023 “Thermal Injuries During Surgery”

· March 2024 “ECRI Top 10 Health Technology Hazards for 2024”

Some of our prior columns on patient safety issues related to MRI:

· February 19, 2008 “MRI Safety”

· March 17, 2009 “More on MRI Safety”

· October 2008 “Preventing Infection in MRI”

· March 2009 “Risk of Burns during MRI Scans from Transdermal Drug Patches”

· January 25, 2011 “Procedural Sedation in Children”

· February 1, 2011 “MRI Safety Audit”

· October 25, 2011 “Renewed Focus on MRI Safety”

· August 2012 “Newest MRI Hazard: Ingested Magnets”

· October 22, 2013 “How Safe Is Your Radiology Suite?”

· October 21, 2014 “The Fire Department and Your Hospital”

· August 25, 2015 “Checklist for Intrahospital Transport”

· August 2016 “Guideline Update for Pediatric Sedation”

· October 2016 “MRI Safety: There’s an App for That!”

· January 17, 2017 “Pediatric MRI Safety”

· August 8, 2017 “Sedation for Pediatric MRI Rising”

· March 2018 “MRI Death a Reminder of Dangers”

· March 2018 “Cardiac Devices Safe During MRI But Spinners!?”

· November 2018 “OMG! Not My iPhone!”

· April 2, 2019 “Unexpected Events During MRI”

· September 2019 “New MRI Hazard: Magnetic Eyelashes”

· October 15, 2019 “Lots More on MRI Safety”

· November 5, 2019 “A Near-Fatal MRI Incident”

· November 2019 “ECRI Institute’s Top 10 Health Technology Hazards for 2020”

· January 7, 2020 “Even More Concerns About MRI Safety”

· March 2020 “Airway Emergencies in the MRI Suite”

· October 2020 “New Warnings on Implants and MRI”

· January 2021 “New MRI Risk: Face Masks”

· June 1, 2021 “Stronger Magnets, More MRI Safety Concerns”

· November 2021 “Yet Another Risk During MRI”

· January 2022 “MRI Safety Issues”

· July 26, 2022 “More Risks in the Radiology Suite”

· October 24, 2012 “Serious MRI Accident at Unregulated MRI Center”

· November 21, 2023 “Another Terrifying MRI Accident”

· January 2024 “Guns and MRI Don’t Mix”

· February 20, 2024 “What is a “Safety Case”?”

· June 11, 2024 “Nursing in the MRI Suite”

References:

Delfino J., Krainak DM, Flesher SA, Miller L. MRI-related FDA adverse event reports: A 10-yr review. Med. Phys 2019; 46: 5562-5571

https://aapm.onlinelibrary.wiley.com/doi/full/10.1002/mp.13768

Baker C, Nugent B, Grainger D, et al. Systematic review of MRI safety literature in relation to radiofrequency thermal injury prevention. J Med Radiat Sci 2024; First published: 27 June 2024

https://onlinelibrary.wiley.com/doi/10.1002/jmrs.800

FDA. MRI Burn Prevention Poster.

https://www.fda.gov/media/94595/download?attachment

American College of Radiology (ACR). ACR Manual on MR Safety 2024. ACR 2024

https://www.acr.org/-/media/ACR/Files/Radiology-Safety/MR-Safety/Manual-on-MR-Safety.pdf

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