MRI Question

[Joel Goodman]

My doc tells me I need an neck MRI to diagnose some arm pain that may be starting in the neck. On the phone the MRI facility asked me if I had ever been involved with "metal grinding". Of course as a woodworker I've sharpened tools on a wheel, drilled holes in metal etc. I'm hoping to get more answers from the techs tomorrow but has anyone here been through this? Are they concerned about stuff in the eye or ? that might be pulled by the magnet. Any information would be appreciated -- this is all rather alarming!

[Dan Hintz]

Yes, they're concerned about metal, though unless you have any chunks embedded in your skin I wouldn't worry about it. Drilling a few holes or sharpening some tools is not the same as working metal all day long.

The gauss level in an MRI machine is pretty impressive, and it can rip metallic implants right out of your body.

[Jim Koepke]

Likely a routine question.

There is some very strong magnetics going on during an MRI. The hardest part is keeping still while they are making the images.

After about 60 years of age depending on how wreak-less one was during life it becomes difficult each morning to determine if you have more aches or more pains.

Though I have not suffered many broken bones other than a slight skull fracture and a smashed finger I did get in a few bad situations. They didn't mess with me much when I was young, but the seem to come back to remind me in my later years.

Good luck, hope they find something that can be remedied instead of the "well, you will just have to live with it" they found for me.

For me, taking care of how I lay when falling asleep has a lot to do with how I will feel in the morning.

I tried a chiropractor, but that taught me, "the purpose of the spine was to support the chiropractor." (That is supposedly a quote from Daniel David Palmer, the founder of chiropractic medicine.)

jtk

[Joel Goodman]

After about 60 years of age depending on how wreak-less one was during life it becomes difficult each morning to determine if you have more aches or more pains.


jtk

+1 !!!!!!!!!

[Brian Elfert]

I had an MRI about 18 months ago. About 18 months before that I got metal in the eye from grinding that was removed. They wouldn't do the MRI without xraying my eye to be sure the metal was all gone. I guess they didn't want any metal being pulled out of my eye, which is a good thing.

[paul cottingham]

I grind most of my tools, and have had 3 or 4 (probably more) MRI's on my neck and head in the past 3 years. Never had a problem beyond having to get my shunt reset. Oh, and the fact my shoulders are wider than the tube. But that's not germaine.
YMMV of course.

[Ken Fitzgerald]

Dan,

I installed and maintained 0.5 - 3.0 Tesla MRI scanners for 24 years. I have a little experience with them.

MRI scanners won't rip implants out of your body unless it was a large ferrous implant. Let's don't overstate the case and cause people unnecessary fear. You do need to be cautious, however.
The technologist who operate MR scanners actually have a reference book that states which and what type of implants and other surgical hardware can be scanned.

The most common magnetic field strength of MRI scanners is 1.5 Tesla or in another measure 15,000 gauss. Now to give you an idea of how powerful that magnet is, the earth's magnetic field strength is commonly accepted as field strength of 0.67 gauss. A disclaimer, however, physicists routinely argue this value. So the most commonly used magnetic field strength magnet is 25,000 times the earths magnetic field strength. Remember we are talking magnetic field strength...that which causes your compass needle to point to magnetic north. These MRI scanners typically are in special rooms with specially annealed steel in the walls to keep the magnetic field in the room or they are specially constructed magnets with reverse wound coil wires on the outside which keeps the magnetic field in the room.

Some MRIs are considered low field (0.2-0.5 tesla), mid-field (1.0 tesla) and others are high field, 1.5 tesla 3.0 tesla and above.

The reason they ask that question about whether you have ground steel or ferrous metals is potentially the magnet could move the metal in your eye and damage the surface of the eye in the process. Often if there is doubt, they will shoot a head x-ray prior to doing the MRI exam. If they can see the metal, they won't do the MRI. Don't be alarmed!

I have been scanned hundreds of times. There are imaging artifact problems that cannot be realized on test phantoms due to their homogeneity. Thus, to see if a problem has been resolved, a human body needs to be scanned. Often late at night it would be just myself and the radiological technologist there. So the tech scanned me. I had a piece of steel in my arm from an oil field accident. It was there for over 40 years. Only when I knew I was going to have to install and work on a 3.0 Tesla magnet did I have the steel chip removed from my arm. When working inside the bore 1.5 T magnets I could feel the small chip of steel twist and knew it should be removed before working on the 3.0 T magnet. In fact, my employer, a large manufacturer, required us to acknowledge any stainless steel in our bodies. If people had had surgery and had screws, they had to obtain a certificate from their surgeon with the type of screw and the quality of the stainless steel used. If the screw didn't meet certain specification, you weren't allowed to work on high field MRIs.

You will probably be asked if you have any implants like a pacemaker, cochlear implant and other implanted devices.

The reason they ask about pacemakers that the magnetic field is capable of resetting/erasing the cardiac pacemakers memory. I actually witnessed this once.

The reason a cochlear implant(CI) can't be scanned is because of the rare earth magnet that is part of the implant. The antenna of the CI sound processor which looks like a hearing aid has a rare earth magnet on it. The implant under the scalp has a magnet. The two magnets hold the antenna to the scalp. The sound processor takes sound, amplifies and modulates a radio signal which goes down a small cable to the antenna and is transmitted through the scalp to the implant. I can have MRI scans but ONLY if I undergo minor surgery first, the magnet is removed, the scan performed and then the magnet surgically reinstalled on the implant. I have a CI and a recent study says that I could possibly have a scan but I wear a medical alert necklace saying "Cochlear implant....No MRI....No mono-polar cautery"at my surgeons recommendation.

I won't bore you with details about what a 1.5 T magnet is capable of but....I saw a patient bed stuck to magnet.....I saw a large metal rolling tool cart being used as a anesthesia crash cart stuck to a magnet. Keep in mind, both of these items have a LOT of steel and were very close to the magnet before they were attracted and attached to it. In either case, they shouldn't have been positioned that close to the magnet but the people who were moving them, neither of which were MRI trained radiologic technologists, were either unaware or inattentive to the rules when working around such devices.

Don't be worried....answer the questions. If in doubt, the MRI technologist won't scan you.

Don Orr, a fellow Creeker, IIRC operates MRI scanners and would be more knowledgeable.

[David C. Roseman]

Dan,

I installed and maintained 0.5 - 3.0 Tesla MRI scanners for 24 years. I have a little experience with them.

MRI scanners won't rip implants out of your body unless it was a large ferrous implant. Let's don't overstate the case and cause people unnecessary fear. You do need to be cautious, however.
The technologist who operate MR scanners actually have a reference book that states which and what type of implants can be scanned.

The most common magnetic field strength of MRI scanners is 1.5 Tesla or in another measure 15,000 gauss. Now to give you an idea of how powerful that magnet is, the earth's magnetic field strength is commonly accepted as field strength of 0.67 gauss. A disclaimer, however, physicists routinely argue this value. So the most commonly used magnetic field strength magnet is 25,000 times the earths magnetic field strength. Remember we are talking magnetic field strength...that which causes your compass needle to point to magnetic north. These MRI scanners typically are in special rooms with specially annealed steel in the walls to keep the magnetic field in the room or they are specially constructed magnets with reverse wound coil wires on the outside which keeps the magnetic field in the room.

Some MRIs are considered low field (0.2-0.5 tesla), mid-field (1.0 tesla) and others are high field, 1.5 tesla 3.0 tesla and above.

The reason they ask that question about whether you have ground steel or ferrous metals is potentially the magnet could move the metal in your eye and damage the surface of the eye in the process. Often if there is doubt, they will shoot a head x-ray prior to doing the MRI exam. If they can see the metal, they won't do the MRI. Don't be alarmed!

I have been scanned hundreds of times. There are imaging artifact problems that cannot be realized on test phantoms due to their homogeneity. Thus, to see if a problem has been resolved, a human body needs to be scanned. Often late at night it would be just myself and the radiological technologist there. So the tech scanned me. I had a piece of steel in my arm from an oil field accident. It was there for over 40 years. Only when I knew I was going to have to install and work on a 3.0 Tesla magnet did I have the steel chip removed from my arm. When working inside the bore 1.5 T magnets I could feel the small chip of steel twist and knew it should be removed before working on the 3.0 T magnet. In fact, my employer, a large manufacturer, required us to acknowledge any stainless steel in our bodies. If people had had surgery and had screws, they had to obtain a certificate from their surgeon with the type of screw and the quality of the stainless steel used. If the screw didn't meet certain specification, you weren't allowed to work on high field MRIs.

You will probably be asked if you have any implants like a pacemaker, cochlear implant and other implanted devices.

The reason they ask about pacemakers that the magnetic field is capable of resetting/erasing the cardiac pacemakers memory. I actually witnessed this once.

The reason a cochlear implant(CI) can't be scanned is because of the rare earth magnet that is part of the implant. The antenna of the CI sound processor which looks like a hearing aid has a rare earth magnet on it. The implant under the scalp has a magnet. The two magnets hold the antenna to the scalp. The sound processor takes sound, amplifies and modulates a radio signal which is goes down a small cable to the antenna and transmitted through the scalp to the implant. I can have MRI scans but ONLY if I undergo minor surgery first, the magnet is removed, the scan performed and then the magnet surgically reinstalled on the implant. I have a CI and a recent study says that I could possibly have a scan but I wear a medical alert necklace saying "Cochlear implant....No MRI....No mono-polar cautery"at my surgeons recommendation.

I won't bore you with details about what a 1.5 T magnet is capable of but....I saw a patient bed stuck to magnet.....I saw a large metal rolling tool cart being used as a anesthesia crash cart stuck to a magnet. Keep in mind, both of these items have a LOT of steel and were very close to the magnet before they attached to it. In either case, they shouldn't have been positioned that close to the magnet but the people who were moving them, neither of which were MRI trained radiologic technologists, were either unaware or inattentive to the rules when working around such devices.

Don't be worried....answer the questions. If in doubt, the MRI technologist won't scan you.

Don Orr, a fellow Creeker, IIRC operates MRI scanners and would be more knowledgeable.

Holy smokes! The things I learn from the off-topic forum never cease to amaze me. Thank you, Ken!

David

[Matt Meiser]

I've done a number of projects in metal machining facilities and have had a couple MRIs. They just did an Xray each time.

[Joel Goodman]

I've done a number of projects in metal machining facilities and have had a couple MRIs. They just did an Xray each time.

That was to check for possible stuff in your eyes -- right?

[Harvey M. Taylor]

David beat me to it. Thank you for the explanation,Ken.Max

[Ty Williams]

Ken's answer is basically all you need to know, but I figure most people who are worried about medical things often like to hear multiple voices saying the same thing. My wife is a physicist that works in medical imaging research and she studied imaging modalities, including MR, at the graduate level. I'm a mechanic, which is one of the "red flag" jobs for clinical MR. So, add those two together, and I've got more experience than most with the issue you're facing. Ken's right, there's very little real risk to you at all. However, they will bend over backwards to check and double check that everything is going to be ok if they have any reason to be concerned at all. However, the bigger "risk" is that you'll start to feel something that'll freak you out, not that you'll be in danger. Metal in your body can increase in temperature or move/buzz slightly when in an MR machine. Someone who's strapped down inside a noisy machine, in an environment that's not that comfortable and is slightly unfamiliar can easily be spooked by either of these things happening long before anything dangerous goes on. With my job, their primary concern is rust and metal filings. Basically, they're worried that I could have had rust fall into my eyes or my ears or that I could have inhaled iron filings and have them lodged in my sinuses. So, every time I go to have a scan, I first get a trip to the x-ray machine. They shoot my head from multiple different angles to make sure that they can't see anything at all. If they have even the slightest doubt, they'll shoot me again. If I'm having a series of MR scans over several days, they won't let me back into the MR without first x-raying me again if I've so much as walked into the shop since the last time they x-rayed me. So far, everything has been completely uneventful for me.


Now that pales in comparison to how careful they are with people around the 11T research scanner!

[Dan Hintz]

One thing I have not been able to find... are today's X-rays sensitive enough (i.e., high definition) to recognize metal dust particles? See a small chunk of metal is a no-brainer, and I can imagine a high concentration of metal dust in one area as being visible like a clouding of the image (similar to a tumor). But a few specs of metal dust picked up while working? I didn't think the definition was nearly high enough for that...

[Matt Meiser]

That was to check for possible stuff in your eyes -- right?

Yes, that''s correct.

[Ken Fitzgerald]

Joel,

Yes, a head x-ray is what they would shoot to see if you have metal in you eyes.