Gun goes off in MRI

[Van Canna]

http://www.ajronline.org/cgi/content/full/178/5/1092

WTF Bill...Ian?

[Bill Glasheen]

Funniest thing I've heard in a while, Van. I have GOT to send this to my biomedical engineering colleagues.

Yes, these magnets are THAT strong. If you bring your wallet anywhere near one of these machines, it'll erase all the vital information on the magnetic strips of your bank and credit cards.

Yes, somebody REALLY screwed up in managing this patient.

I had to go through the text very carefully to figure out what happened. This is how the round went off.

• This was a semiautomatic pistol.
• Even though the safety was on, a round was in the chamber.
• When the MRI tech fired up the magnet (perhaps too soon), it pulled the gun out of the officer's hand and it went flying to the magnet.
• The force of the collision of the gun on the side of the magnetic core caused the round to fire - as if the hammer had hit the round itself.

Make sense?

That's some crazy schit. Publishing this incident IMO is a very good thing. We know these magnets are capable of doing bad stuff to our possessions. But this one's a real freakish example.

- Bill

[Bill Glasheen]

Another interesting thought... Imagine the path of that round with the bullet emerging from the gun in that intense a magnetic flux. It would be the equivalent of Tim Wakefield throwing one of his patented knuckleballs in gale force winds.

Tim Wakefield Knuckleball

- Bill

[Bill Glasheen]

I still can't get over this picture.

Photograph shows gun (arrow) stuck on right side of MR imaging magnet bore

Imagine being the tech who walks in on this. Holy cr@ap, my boss is gonna kill me!

Looks like they got the image off of the video monitor. Otherwise he may have tried to cover the whole incident up.

- Bill

[Glenn]

Another interesting thought... Imagine the path of that round with the bullet emerging from the gun in that intense a magnetic flux. It would be the equivalent of Tim Wakefield throwing one of his patented knuckleballs in gale force winds.

That's what I was wondering about. On the one hand the bullet would have a lot of energy in its motion, but the magnetic field is so strong I could definitely see it causing distortion in the path of the bullet. That could be an interesting high-speed photography experiment.

[Bill Glasheen]

That's what I was wondering about. On the one hand the bullet would have a lot of energy in its motion, but the magnetic field is so strong I could definitely see it causing distortion in the path of the bullet. That could be an interesting high-speed photography experiment.

Given the forces involved - and assuming the round was magnetic - it probably would have looked a little bit more like this.

Blitzball : Amazing Curveballs

Back in the Dominican Republic, David Ortiz and his buddies used to play stickball with bottle caps. That's the kind of motion you're talking about. Definitely something that would prepare you for The Big Show.

- Bill

[Van Canna]

Every day...something new...

[Glenn]

The force of the collision of the gun on the side of the magnetic core caused the round to fire - as if the hammer had hit the round itself

To add a little more detail to what specifically caused it to fire:

The gun likely discharged as a result of the effect of the magnetic field on the firing pin block. The firing pin block was probably drawn into its uppermost position by force of the magnetic field. The firing pin block has to overcome only light pressure from a relatively small spring to release the firing pin. The pistol was likely drawn into the magnetic field so that the muzzle struck the magnet's bore first. With the firing pin allowed to move freely in its channel, the force of the impact on the muzzle end was sufficient to cause the firing pin to overcome its spring pressure and move forward to strike the primer of the chambered round.

As I understand this, the magnetic field shifted the firing pin block in a way that would enable the firing pin to move freely, then as luck would have it the gun hit the magnet muzzle first. While the gun stopped at that point, the firing pin was able to slide forward under inertia with enough force to overcome the spring and strike the round. No hammer needed. If any other part of the gun had hit the magnet first then it likely would not have gone off.

I would also assume that when the muzzle of the gun hit the magnet the rest of the gun was immediately drawn sideways to it so that when the gun discharged the bullet traveled parallel to the chamber, otherwise the magnet itself probably would have been hit.

[Bill Glasheen]

Glenn

I'd like to know who you are quoting.

So sorry about my sloppy labeling. Indeed you have a hammer on a revolver and a firing pin in a semiauto. That being said...

I thought about what you posted above. Yes, it's possible, but...

Methinks Occam's Razor applies here. The sequence of events described are so bizarre that it seems a bit implausible. I'm thinking the gun likely would not have been able to rotate fast enough in space after that first hit. You need the gun to come forward with the firing pin continuing to move after the end of the barrel hit the side of the magnetic core. Then the gun would have to have rotated very quickly in space so that the round wouldn't have left a mark anywhere on the core. Possible? Maybe. Probable?

Occam tells us that the simpler explanation is more likely. Slam a round hard enough and it can cause combustion.

What do you say we contact Myth Busters and see if they'll test the various theories? I'll send the note if you think it's worth doing. Hey with any luck, maybe they'll let me visit and play mad scientist with them.

- Bill

[mhosea]

Speaking of Mythbusters, they did a show on bullet deflection by magnetic field (it was based on a "Live and Let Die" scene). The results were that it takes a helluva lot of magnetic force to appreciably change the trajectory of a suitably jacketed bullet. They were only able to alter the trajectory slightly in close proximity to a dozen or so very serious rare earth magnets. Not sure how the force compared to an MRI.

[Glenn]

Glenn

I'd like to know who you are quoting.

Sorry, I should have included that. It's from the original article Van posted that started this thread:
http://www.ajronline.org/cgi/content/full/178/5/1092
third paragraph from the end of the "Case Report" section.

I thought about what you posted above. Yes, it's possible, but...

Methinks Occam's Razor applies here. The sequence of events described are so bizarre that it seems a bit implausible. I'm thinking the gun likely would not have been able to rotate fast enough in space after that first hit. You need the gun to come forward with the firing pin continuing to move after the end of the barrel hit the side of the magnetic core. Then the gun would have to have rotated very quickly in space so that the round wouldn't have left a mark anywhere on the core. Possible? Maybe. Probable?

Occam tells us that the simpler explanation is more likely. Slam a round hard enough and it can cause combustion.

I gotta say I was thinking the same thing when I was typing my earlier assumption about how the bullet would have missed the MRI. But look at the picture from the article that shows the point of impact on the gun: "Muzzle of gun shows small amount of white paint (arrow) where gun impacted magnet", so how is it that if the gun hit the magnet there that it

discharged a round into the wall of the room at the rear of the magnet. Fortunately, no one was injured. Although the gun struck the magnet bore, only minimal cosmetic damage occurred to the magnet itself.

While they never specifically state that the bullet did not hit the magnet, that is my assumption from what they do say.

I'm thinking this might be in the realm of Einsteinian physics!

What do you say we contact Myth Busters and see if they'll test the various theories? I'll send the note if you think it's worth doing. Hey with any luck, maybe they'll let me visit and play mad scientist with them.

I say go for it! Good luck finding someone willing to donate an MRI for the experiment though.

I think working on that show would be my dream job.

[IJ]

Minor addendum:

The MRI was not "fired up too soon." MRI machines are up and running, generally continuously. It takes a lot of time and energy to stop and start these things, which is why the didn't just power down the MRI to remove the gun, but rather spent some time trying to yank the gun free first, probably terrified of another discharge in the process.

These magnets are strong enough to vibrate your water molecules. That's how they make pictures. They also can cause electrical currents and rarely induce burns on skin. And if you have any bits of metal in your eyeball, or a pacemaker--things get really ugly. I do not have the ability to laugh at any MRI incident because I am always reminded of an event where a 10 year old (?) child was killed instantly when an O2 tank was sucked into the machine he was in probably at obscene speeds and hit him in the head. The resulting scene probably ruined several lives, not just those who lost their child and those who must carry around self blame for life, but also just those who saw it. I can hardly think of anything worse.

[Van Canna]

child was killed instantly when an O2 tank was sucked into the machine he was in probably at obscene speeds and hit him in the head.

Can you give more particulars IAN? This is unreal...where was the foreseeability on this one?

So what happens if you have some metal in your body? No MRI?

[Van Canna]

It takes a lot of time and energy to stop and start these things, which is why the didn't just power down the MRI to remove the gun, but rather spent some time trying to yank the gun free first, probably terrified of another discharge in the process.

Imagine that...

Wanting to save a few bucks, and taking a chance the gun might go off again...

Though I hope someone who know guns was called to the scene to determine the proper way to handle that gun.

My first thought would be that when the round in the chamber went off...the slide might not have cycled an ejection of the empty brass and insertion of a new round into battery.

But then again...this reminds me of the malpractice cases I investigated...

[Bill Glasheen]

So what happens if you have some metal in your body? No MRI?

You got it!

As Ian stated... If you're Joe Machinist and happen to have a metal fragment somewhere in the eyeball, this can spell bad news.

- Bill