A 39 y/o patient is scheduled for an MRI to assess her “back pain”. She has no significant medical problems other than the back pain listed above. Her vitals signs are WNL. She’s only a social drinker and is a smoker but is currently trying to quit using OTC nicotine patches. Her family history is non-contributory.

The patient starts her MRI and soon complains of a burning spot on her chest. The test is stopped. The machine was just calibrated recently and there’s no other alarms or indication of a system malfunction.

What’s the problem?

SELECT  here for discussion

The cause is most likely her nicotine patch, being used by the patient to quit smoking.

The MRI uses a radio frequency pulses to generate the magnetic field. “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.” See full reference below and attached hyperlinks for more details.

Bottom line – besides any other pre-MRI checklist and check for other metal objects, be sure to check your patient for the use of various transdermal patches, some OTC and some prescription, before they enter the MRI.

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), 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 http://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.  (ISMP newsletter. 8 April 2004;9:7)

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.)

Follow-up from last week’s Pearl on COX2s and the S.C.O.R.E. – The DoD Basic Core Formulary (BCF) includes meloxicam [Mobic®]. The BCF is the required minimum for all DoD MTFs worldwide. 

Mobic® is a relatively selective COX2 inhibitor although it does NOT carry the COX2 inhibitor moniker from the FDA. It’s may be a useful and cost-effective alternative to the COX2s and can be tried before going with whatever other COX2 the provider may choose.

Caution – Mobic® should NOT be used in patients who have no risk factors for GI toxicity and for whom generic ibuprofen or naproxen should work just fine. The incremental benefit isn’t worth the incremental cost in this case. Mobic® is NOT a cost effective alternative to generic ibuprofen or naproxen in these low-risk cases.

Mobic® may be an alternative in a patient who IS a candidate for a COX2. Although more expensive than generic non-selective NSAIDs, Mobic® is less expensive than the COX2s. In this situation, Mobic® may be a cost effective alternative to COX2 inhibitor.

Drug costs of selected strengths of available selective NSAIDs (for comparison only) in order of cost per dose:

Mobic® 15mg -    $ 0.97/tablet

Vioxx® 25mg -    $ 1.23/tablet

Celebrex® 200mg -    $ 1.39/capsule

Bextra® 20mg -    $ 1.39/tablet

This Pearl is meant for academic and educational purposes only. This Pearl is meant to raise important points regarding the safe and cost-effective pharmacotherapy of patients. It is not meant to be the definitive reference for the treatment or prophylaxis of various diseases. Although every effort is taken to ensure this Pearl is correct and factual, errors may occur. The US Air Force, the 59th Medical Wing (MDW), and 59th MDW Pharmacy assume no liability for incorrect information or harm that may occur from the use of the information included in this Pearl.