I had an MRI earlier this year and was cautioned about having any metal on me, and they wanted a full inventory of any medical metal I might have in my body (none). But then they put a pair of headphones on me so I can listen to music (every genre except jazz :smack:) during the test.
Why are headphones OK in an MRI machine but not any other metal? Headphones even have magnets in them.
The headphones you use in an MRI are nonmetallic. They are connected to an external speaker by a hollow tube – very low-tech.
Here’s one, with a fairly complete technical description.
The reminds me of the headphones you used to get on international flights back in the 1970s; they were all-plastic construction, just pneumatic tubes that you plugged into the armrest, with the whole system functioning a bit like a speaking tube.. Always wondered where the driver was that was moving that air. Surely there wasn’t one speaker for every seat? Maybe one for every row?
I always wonder about the gold in my teeth.
That explains the shitty sound quality.
Well, at least it gives you something to think about during the 20 minutes of absolute immobility during the test. THRUM THRUM BANGBANGBANG MRRRRRRRRRR VIPVIP THRUM
Gold isn’t magnetiTHRUM BANGBANG … what was I saying again? Oh yea, neither is titanMRRRRRRRR CLICKCLICK MRRRRRRRRRRRRRRRR… titanium. or medical stainlesBRACCCCCKKKK MRRRRR ok that was a loud one.
Which is much better than have an allergic reaction to the contrast dye. Ask me how I know…
You might be interested in this article about how MRI design was modified at a children’s hospital Creative Confidence: A new book from IDEO's Tom and David Kelley
I want the space ship one.
I’d see those on domestic flights, too, until fairly recently (I think it’s only been the past few years where they finally gave up on that system). I’d always wondered about the tech behind those, too.
According to Wikipedia, Delta was the last airline still using them, and stopped in 2003. Apparently pneumatic headphones used to be dirt-cheap, but over time it became economical to hand out electric ear buds like candy.
More info here, and here:
You think that’s disconcerting…
Try having to answer “Yes” to “Have you ever had metal filings in your eyes?” Then they ask you a couple of questions about it, shrug, and conclude “It should be OK.”
Hmm, longer ago than I realized. Thanks!
I feel your pain. I had some bulging disc issues a few years ago and ended up having several MRI’s. They were all at the same place, but I never managed to get the same person, so I had to go through all the questions each time. By the time I finished getting all the MRI’s, I think I knew the questions better than they did.
The thing I disliked the most about the MRI questions were how many times I was asked if I was claustrophobic.
Them: “Are you claustrophobic?”
Me: “no”
Them: “Have you ever been claustrophobic?”
Me: “no”
Them: “Have you ever had problems with tight/enclosed spaces?”
Me: (Sigh)…“no”
Them: “Are you sure you aren’t claustrophobic?”
Me: (Siiiiighhhh)…“I am sure”
By the time they are done trying to convince me that I might be claustrophobic, I am beginning to wonder if I could be claustrophobic and just didn’t know it. Then they slide me in the tube and tell me to be as still as possible. Since I have been in so much pain for so long, I wasn’t sleeping well, so any time I sat still, I would fall asleep; then I would move, which would hurt, which would wake me up. Being that there isn’t a lot of room to move and they would strap me in, I was able to lie fairly still and would fall asleep within a few minutes, which would always amaze these folks. They would always say they have never had someone fall asleep in the machine, I would beg them to put something in my chart that would tell the next person that I was truly comfortable with enclosed spaces and there was no need for all the claustrophobic questions, but they never did.
The magnetic fields in MRI machines only affect ferromagnetic materials, the most common of which include iron, nickel, cobalt, and their alloys. Cite.
So your gold teeth are fine unless they are alloyed with a ferromagnetic material.
From your cite, the static magnetic field only affects ferromagnetic materials. But the time-varying magnetic field can induce electrical currents in other metals: