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A 10-year Review of MRI-Related FDA Adverse Event Reports
Jana G Delfino1, Daniel M Krainak1, Stephanie A Flesher1, and Donald L Miller1
1US Food and Drug Administration, Silver Spring, MD, United States

Synopsis

We provide a breakdown of the adverse event reports received by FDA during a 10-year period (2008-2017). Reports were manually categorized into eight mutually-exclusive event types. Thermal events were further sub-categorized by probable root cause. Objects that became projectiles were sub-categorized. Adverse events related to MR systems consistent with the known hazards of the MR environment continue to be reported to FDA. Thermal events were the most commonly reported serious injury (59% of analyzed reports). Mechanical events (11%), projectile events (9%), image quality issues (6%), and acoustic events (6%) were also observed.

Purpose

Adverse events consistent with the known hazards of the MR environment continue to occur and to be reported to FDA. As the clinical applications of MR imaging continue to grow, it is especially important that all of those involved in patient care, including MR technologists, medical physicists, and physicians, are aware of the unique safety challenges associated with the MR environment. The purpose of this study was to provide an overview of the adverse event reports received by FDA for MR systems over a 10-year period (2008-2017).

Methods

For this analysis, all adverse event reports received by FDA between January 1, 2008 and December 31, 2017 (inclusive) for MR imaging systems (FDA product code LNH), MR specialty coils (FDA product code MOS), NMR spectroscopy (FDA product code LNI), and PET/MR systems (FDA product code OUO) were retrieved. This included adverse event reports received through MedWatch1, MedSun2 and alternate summary reporting3 mechanisms. Two FDA adverse event analysts independently reviewed these adverse events and manually categorized each adverse event report into one of eight mutually-exclusive event types described below.
  • Thermal - Skin reddening, blisters, burns, warming, heating sensation, fires, and smoke
  • Acoustic - Hearing loss and/or tinnitus (temporary or permanent)
  • Image Quality- Lost, misoriented, inadequate, or mislabeled images. These include items such as image artifact, image flipping, and images attributed to the incorrect patient. An error anywhere along the image acquisition chain may fall into this category.
  • Projectile - Events in which objects were pulled into or attracted to the main static magnetic field
  • Mechanical - Slips, falls, crush injuries, broken bones, and cuts; musculoskeletal injuries from lifting or movement of the device were considered mechanical events.
  • Peripheral Nerve Stimulation - Nerve or muscle stimulation or patients experiencing ‘tingling,’ ‘twitching’ or involuntary movements. (When tingling was reported in conjunction with heating or blistering, the event was classified as a thermal injury)
  • Miscellaneous - Adverse event reports for which a sufficient narrative was provided to describe the event, but the event did not fit into the above categories. (These are events that are clearly linked/attributed to or caused by the MR system.)
  • Unclear -Insufficient information was available to draw any conclusions, or the event description and/or conclusion are inconclusive or contradictory. Events describing symptoms or a clinical narrative for which the connection to the MRI exam is unclear were placed into this category.

Discrepancies in event categorization were flagged and discussed by the two analysts with the aim of reaching agreement on the appropriate categorization of a flagged event. If no agreement could be reached, the event was referred to a third individual for adjudication.

Thermal events were further sub-categorized by probable cause. For projectile events, the object that became a projectile was recorded.

Results

Between January 1, 2008 and December 31, 2017, FDA received 1568 adverse event reports for MR systems. These 1568 reports included 6 reports of adverse reactions to MR contrast agents and 14 miscoded events, which were excluded from further analysis, leaving 1548 reports for review.

Thermal events were the most commonly reported serious injury (59% of analyzed reports). Mechanical events, defined as slips, falls, crush injuries, broken bones, and cuts and musculoskeletal injuries from lifting or movement of the device compromised 11% of reports. Projectile events (9%), image quality issues (6%), acoustic events (6%), unclear events (4%) and miscellaneous events (7%) were also observed. (Total percentage may not be 100 due to rounding).

The probable root cause of the 906 thermal injuries was as follows: unclear (39%), contact with an object (28%), skin-to-skin contact (16%), bore contact (10%), and not RF related (6%). Objects involved in burn injuries with a probable root cause of contact with another object included: MR coils (54%), ECG electrodes or leads (15%), patient clothing (5%), stereotaxic head frames (4%), blankets (4%), orthopedic implants (3%), pulse oximeters (3%), tattoos/permanent makeup (2%), headphones (1%), dermal patches (1%), jewelry (1%) and miscellaneous (7%). (Total percentage may not be 100 due to rounding).

Objects involved in projectile events included: patient transport and mobility equipment (26%), gas cylinders (10%), magnet components exposed during service (10%), tools (8%), patient monitoring equipment (7%), carts (6%), IV poles (6%), surgical tools (5%), firearms (4%), floor polishers (2%), firefighting equipment (2%), and miscellaneous (14%).

Limitations

The major limitation of this retrospective study is that the adverse event reports are derived from a passive reporting system that relies on information provided by users of the devices and other sources, and therefore information about certain events may be missing, inaccurate, or unverified. These data cannot be used to determine rates of adverse events, and thus cannot provide a complete picture of MRI safety.

Conclusions

Adverse events consistent with the known hazards of the MR environment continue to occur and be reported to FDA. The majority of these events have known causes and are preventable. Reducing the occurrence of these preventable events is a shared responsibility among all those working within the field of MR.

Acknowledgements

No acknowledgement found.

References

[1] US Food and Drug Administration. Reporting Serious Problems to FDA. https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program/reporting-serious-problems-fda. Accessed July 2, 2019.

[2] US Food and Drug Administration. MedSun: Medical Product Safety Network. https://www.fda.gov/medical-devices/medical-device-safety/medsun-medical-product-safety-network. Accessed July 2, 2019.

[3] US Food and Drug Administration. MDR Data Files https://www.fda.gov/medical-devices/medical-device-reporting-mdr-how-report-medical-device-problems/mdr-data-files. Accessed July 2, 2019.

Proc. Intl. Soc. Mag. Reson. Med. 28 (2020)
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