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May 21, 2007

Think: Major Risk of Injuries

Laura Nathanson, MD, FAAP

MRI actually stands for Magnetic Resonance Imaging. But Major Risk of Injuries is an equally accurate moniker, and more to the point for patients and those who love them.

What You Should Know About MRIs:

The good things:
1. They are enormously useful, because they can see soft tissues and fluids.
2. They deliver no harmful radiation at all.

The risky things:
The Major Risk problems occur because the Magnetic force of the MRI is incredibly powerful. In fact, it is so powerful it acts on the nuclei of the atoms of the molecules that make up the biochemicals that compose our bodies. Any metal that can be magnetized will be powerfully affected by the MRI.
The verb affected covers a lot of territory here. All of the following apply both to the patient on the table and to anyone else in the room:

Here is what can happen as soon as you enter the MRI suite:
1. Any magnetizable metal object you bring in, no matter how large, will be pulled towards the magnet no matter what is in the way -- your head, for instance. A tragic accident occurred when an oxygen tank hurtled out of control and killed the six-year-old patient on the table.
2. Any magnetizable metal object embedded in your body, no matter how tiny, can move, damaging surrounding tissues. These include tiny fragments in a metal-worker's eye, shrapnel, and some prostheses, including dental prostheses.
3. Any magnetizable medical implants can move or malfunction, including aneurysm clips, cochlear implants, and pacemakers. Some complex implants can be affected even though their metal is not magnetizable (I don't know why.)
4. Any magnetizable metal decorating your body, from rings to piercings to eyeliner to tattoo ink, will be agitated, causing a tingling or burning, or your eyelids to flutter weirdly.
5. The magnet is always on. It is never turned off, even at night.You can't just press a switch and turn off the magnet. Once it's on, it's on; turning it off is a big deal -- it involves draining helium, which takes more than a few minutes and carries its own dangers.

The risk enablers:
While there are guidelines for MRI safety, they are not mandated by any governing authority: they are optional.
MRI accidents usually go unreported unless the machine itself has attacked the victim. The flying buckets and pistols go unreported, and so may the disabled pacemaker or the displaced dental prosthesis.
MRI suites, even new ones, may be designed without protections against accidents. See the citations below.

What You Can Do:
Print this or one of the sources listed below and take it with you to your MRI appointment. Go over it with the technician before you walk in the door. If you suspect that you have any embedded object or implanted device that could be affected, clarify whether this is a problem.

Suggested reading:
M.R.I.'s Strong Magnets Cited in Accidents By Donald G. McNeil Jr. Published: August 19, 2005
This excellent website includes a link to the article How Not To Design an MRI Suite. Please be aware that the architectural specialists are from a group called Junk Architects, but that is because Junk is the name of the chief architect; it's not a joke or a hoax.

Dr. Laura Nathanson is the author of What You Don't Know Can Kill You and The Portable Pediatrician, as well as several other books. She has practiced pediatrics for more than thirty years, is board certified in pediatrics and peri-neonatology, and has been consistently listed in The Best Doctors in America.

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