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Burns in MRI patients wearing transdermal
patches
From the April 8, 2004
Because of the strong magnetic field created by the equipment
during magnetic resonance imaging (MRI), ferromagnetic metal
objects can be pulled by the magnet toward the patient on the
scanner table at high speed. In our October 3, 2001 issue, we
wrote about the tragic death of a 6-year-old child in New York
who suffered a skull fracture and intracranial hemorrhage after
an oxygen tank struck him. Prior to MRI, patients are told to
remove all metal objects they may be wearing, and they are asked
about the presence of any metal implants (e.g., pacemaker, prosthetic
hip, implanted intravenous port). Even retained bullets and
shrapnel, tattoos, and permanent eyeliner may create problems.
However, few people are aware that medication patches such
as ANDRODERM (testosterone), TRANSDERM-NITRO
and DEPONIT (nitroglycerin), HABITROL, NICODERM,
and NICOTROL (nicotine), TRANSDERM SCOP (scopolamine),
CATAPRES-TTS (clonidine), and possibly others, should
also be removed prior to scanning.
Some patches are formulated with an aluminized backing that
could potentially cause injury to the patient if worn during
an MRI procedure. MRI systems require the use of radiofrequency
(RF) pulses to create the magnetic resonance signal. When
conducting materials are placed within the RF field, the result
may be a concentration of electrical currents sufficient to
cause excessive heating and tissue damage. The metallic component
of these patches is nonferromagnetic and, therefore, not attracted
to the static magnetic field of an MRI system. However, transdermal
delivery systems with a metallic component are conductive
and can be heated.1
FDA is aware of two adverse events in which patients who
were wearing a nicotine transdermal patch during an MRI experienced
burns. In the first report, a patient entered an MRI scanner
wearing a Habitrol 21 mg patch. He started thrashing upon
initiation of the third scanning cycle, and the test was stopped
immediately. When the patient was removed from the magnet,
he stated that his arm was burning. Upon examination, his
upper left arm was mildly erythematous and there was a small,
denuded, blister where the patch had been residing. In the
second report, a patient underwent a short (less than 40 seconds)
MRI of the lumbar spine while wearing a nicotine transdermal
system patch. Later, the patient complained of burn lines
on his upper arms. In addition to these two cases, a website,
www.mrisafety.com,
reports second degree burns when a patient underwent an MRI
with a Deponit patch in place.
Visit www.newmri.com/html/mr_safety.asp
for a list of objects that cannot be worn during an MRI. In
light of these recent incidents, though, it would be best
to ask all patients about their use of any medication patch.
Unless it is certain that it doesn't contain metal, counsel
patients to remove the patch temporarily before an MRI to
avoid unnecessary burns.
Thanks to pharmacists Linda Y. Kim-Jung, Carol Holquist,
and Jerry Phillips, of the Division of Medication Errors and
Technical Support, Office of Drug Safety, US FDA, for submitting
this report.
Reference (1)
www.mrisafety.com/safety_article.asp?subject=56,
accessed on 3/23/04. (You must first register to access this
website.)
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