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Burns in MRI Patients Wearing Transdermal Patches |
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), TRANSDERMNITRO 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.
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