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One of the cooler medical devices invented in the last 30 years has to be the MRI machine. Introduced in 1977, it represented a huge leap forward in body imaging, allowing doctors to create greatly detailed maps — in two or three dimensions — of an injured knee, a shattered wrist, even a patient’s brain. And while MRI scans are nearly free of side-effects, they’re not completely free of dangers — mostly because the main component of an MRI scanner is an insanely powerful magnet.
How powerful? Some estimates put the strength of MRI magnets at tens of thousands of times the strength of the Earth’s magnetic field. That’s why hospital staff (try to) make sure you remove all jewelry and metallic objects from your person before patients get scanned. Usually metal plates in people’s heads and so on are made from surgical steel that won’t respond to the MRI’s magnet, but there have been cases where metal staples in people’s brains have come loose, triggering aneurysms, and tiny slivers of metal in people’s eyes (from a previous accident, long settled) have moved, blinding them. Pacemakers and MRI machines generally don’t mix, and several deaths have resulted from their unwitting combination.
To really get a sense for how crazy strong MRI magnets are, though, we must turn to YouTube. Here’s a video of what I can only imagine are some unauthorized band of yahoos fooling around after hours:
As MRI magnets have gotten more powerful over the years, magnet-related accidents have spiked. The irresponsible dodos in the video above unknowingly mimicked one of the most notorious MRI fatalities, described this way by the New York Times:
The most notorious accident was the death of 6-year-old Michael Colombini in 2001 at the Westchester Medical Center in Valhalla, N.Y. He was sedated in a scanner after a brain operation when his oxygen supply failed. An anesthesiologist ran for an oxygen tank and failed to notice that the one he found in the hall outside was made of steel. As he returned, the tank shot out of his hands, hitting Michael in the head.
There are other jaw-dropping accidents on the books, too: a police officer who’s gun was sucked from his holster, slammed against the MRI machine’s bore and went off, firing a round into the wall. The “sprinkler repairman whose acetylene tank was yanked inside, breaking its valve and starting a fire that razed the building.” Everything from floor buffers to office chairs have gotten wedged in MRI bores, usually requiring four or more people to pry them out, as in this video:
A lot of people ask, “can’t you just turn the magnet off?” The simple answer is, it’s not that simple. MRI magnets are cooled by liquid helium to eliminate electrical resistance so that their magnetic fields persist indefinitely, so emergency shut-offs involve very rapid venting of the helium in gas form, which can displace oxygen rapidly and be more dangerous than simply leaving the magnet on all the time. How dangerous? Here’s a clip of what happens when an MRI is improperly vented, caught by a local news crew:
Of course, as long as the technicians operating them are being safe, MRIs are safe — all this is meant to illustrate the extreme power they harness. That said, here’s a little “MRI magic” to close:
Comments (13)
Comment
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They are VERY powerful machines.
When I worked for an MRI facility, EVERYONE who worked there (even if you had nothing to do with the machine) had to watch a safety video and sign off on it.
posted by beth on 4-9-2008 at 10:18 am
We had someone working on a door in our MRI department, and he thought that when no one was there that it was turned off, but to his surprise is isn’t and his wrench went flying out of his belt and right through our machine. Needless to say we had to get a new machine.
posted by Alisia on 4-9-2008 at 10:34 am
So, chances are, the steel bar in my left leg (inside the tibia bone) wouldn’t cause me to become permanently stuck to the machine. But will the screws get sucked out and pop out of my skin? EWW.
posted by lleachie on 4-9-2008 at 10:36 am
Is is true about tattoos and MRI’s? I know I saw something on mythbusters a loooooong time ago about it, but I can’t remember the outcome. I have six tattoos and if its true that would make for one painful MRI someday.
posted by Caitlin on 4-9-2008 at 11:11 am
@ Caitlin
I have tattoos and have had MRI’s. No issues.
posted by Florida on 4-9-2008 at 11:42 am
The concerns regarding tattoos and MRI’s have faded with time (no pun intended.) Older tattoo inks (>=20years) had small pieces of metal which would react to the MRI magnet. If your tattoo is less than 20 years old, you should have no problem.
Machinists, however, who shape and craft metal, often have microscopic pieces of metal embedded in their skin, and do face complications with MRI scans.
posted by Jo Ann on 4-9-2008 at 1:02 pm
I am no rocket surgeon, but unless my watch is broken this is the year 2008. The MRI was invented in 1977. That is 31 years ago. Hmmmmmmm
posted by That Guy on 4-9-2008 at 1:37 pm
Why don’t they use the magnetic technology used here to move buckets and buckets of train parts to save the trains from wearing out??
posted by Bill on 4-9-2008 at 3:18 pm
So as well as my claustrophobia triggered panic attack, I’m now going to have to worry about all this… these babies are moving right up there with suspension bridges and heights on my most feared list.
posted by ann on 4-9-2008 at 3:59 pm
Yikes. I’m kind of glad I knew none of this when I had an MRI last year.
posted by Sara on 4-9-2008 at 4:40 pm
Ok I know this is kind of random but I hate MRI machines I once had to have a brain scan b/c of migraines and I full on freaked out inside the tube. It was really scarry and I was never closterphobic before it took like a whole hour b/c I kept hyperventalating and thus moving my head. I would rather die a slow painfull death from brain cancer than do that again.
posted by Shannon on 4-10-2008 at 12:18 pm
remember that great episode of HOUSE where Dr. House used an MRI machine to test his theory that bullets were non-magnetic. after shooting a corpse in the head, he proceeded to destroy the MRI machine. thus proving his theory wrong…
yes, i am a HOUSE addict.
posted by the creature on 4-10-2008 at 1:08 pm
Warning: If you suffer with clostrophobia be sure to have a tranqulizer administered BEFORE an MRI session- my mother became sick and vomited.
posted by Dan on 2-9-2009 at 5:46 pm