As Ken said I am a registered MRI technologist with 20 years experience. His explanation is excellent and very accurate. He knows WAY more about these machines than I ever will. The questions you were asked are indeed standard safety questions we ask every patient before we scan them. A simple Xray can help determine if there is a piece of metal in your eye but it cannot tell what kind of metal. There is a documented case from the early days of MRI where someone had a piece of ferromagnetic metal in his eye, was put in the scanner and lost vision in that eye. We as techs would NEVER want that to happen. We take safety very seriously. I have people give me a hard time about it all the time. A little education goes a long way to help alleviate their concerns-usually.It has come to the point where our facility requires everyone to remove any and all body piercing no matter what they are made of. We also make everyone change their clothes into someting we are absolutley certain has no metal of any kind. These days surgical implants are tested and evaluated for MRI compatibility and most come with a wallet card you can carry that will tell the tech whether it is safe or not. Most surgical implant ARE SAFE-but not all. Mostly they just cause an artifact on the image-sort of a distortion. One of the real problems is that ANY metal can be a hazard whether it is magnetic or not. All metals are conductors of electricity and heat. All metals can have an electric current induced in them when exposed to a time-varying magnetic field and can heat up significanlty. Even tattos can be and are a real problem. Actually the induced current (Faraday's Law) is precisely how MRI works. You will be placed on what is called a coil, which is really an elaborate radio antenna which picks up the signal that is induced in your body. It's a lot more complicated than that but in a nutshell while you are in the scanner you become temporarily magnetized and you become a radio receiver and a radio transmitter.
Essentially MRI is very safe and an extremely powerful diagnostic tool. There is no high energy, ionizing radiation. It is used on tiny little babies to elderly adults an even occaisionally on pregnant women . It is one of the easiest, safest, most detailed non-invasive imaging modalities currently in use. It is, however, very noisy (hearing protection is provided), extremely boring and kind of enclosed if that bothers you. There are very good open MRI's now for the claustrophobic and larger patients.
I also grind my turning tools frequently (not frequently enough but that's another whole discussion) as well as other tools, my lawnmower blades and anything else I feel like, and am in and out of the magnetic field all day every day and have never had a problem. Safety at home is a good start for safety in an MRI. I have also been scanned MANY times as I seem to be the only willing test subject whenever we are learning a new procedure or doing some testing. Easy-peasy, for me anyway. The hardest part for many people is holding still which is critical for getting clear, sharp images.
So definitely talk to the technologist who will be doing your exam and make sure thay have answered your questions thoroughly. It's our job to make sure you are safe and comfortable during your procedure. Some people even fall asleep during their scans. To me that says they are comfortable, relaxed, and safe.
I can't claim to be perfect in my interactions with patients unfortunately. I am a lot better than I used to be. Took some effort and help to get better at it.
As to the shrapnel situation-it could go either way. If it is old and has been there a long time, it is most likey so scarred in place as to not be a problem. Remember-VA hospitals have MRI's too. Recent shrapnel or an unusual location might fly a red flag where we might want to investigate further-maybe with an Xray. Not all doctors are familiar with the limitations and realities of MRI. I could tell you stories.
Bottom line is that MRI's are safe and powerful diagnostic tools-within limits. Any questions, feel free to ask. I am also registered and licensed in Xray and CAT Scan. I hope you find this helpful.
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Originally Posted by Dave Anderson NH
