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 MedWatch
1, MedSun
2 and alternate summary reporting
3 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.