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3. Magnetic Resonance Imaging (MRI or NMR)

MRI can be used to image just about any part of the body, at any angle. It uses a magnetic field to detect what bits of your body are made of and to create a picture. It looks quite a lot like a CT scanner, except it's bigger and noisier.

Let's start off by saying "No, the MRI will not rip jewellery out of your flesh or make your tattoos burst into flame like some surreal Roadrunner cartoon."

Usually, explanations and exceptions below:

Jewellery:

Because MRI uses magnetism, material that is attracted by magnets (ferromagnetic) can be affected by the strong magnetic field. However, most quality jewellery is not ferromagnetic. In particular, anything that is "implant grade" surgical stainless steel or titanium, or is organic, like wood or bone, with stay put. Many other types of metals used in jewellery are also non-ferromagnetic, but as the composition of things that are made of alloys (non-pure gold, or some steel, etc.) can differ, you must check each piece of jewellery individually to see if they are affected by a magnetic field.

NB: hematite, the shiny black stone used extensively for beads in body jewellery, is ferromagnetic - just because it's stone doesn't mean it's safe.

Anyway, assuming that your jewellery is not going to be affected by the magnets, you still might want to remove it. If it is in the area that is going to be imaged, the jewellery is going to interfere with the quality of the image produced. And you want the very best test you can have. Once again, if you choose to keep jewellery in, you will have to state that you're willing to put up with less than ideal results.

Implants:

You should never have a planned implant (whether for medical or other reasons) that does not consist of implant grade material. So whether hip replacement or genital beading, potential interaction of the material with the magnetic field should never be in question. It is always a good idea to have information about your implant material to give to the tech. While implants can also interfere with the quality of the produced image, there are certain technical modifications that can be made to the scan that can account for this.

As for unplanned implants - you're on your own with respect to shrapnel, staples or other foreign bodies - discuss this with the technologist or doctor on duty, preferably before you go to the hassle of making an appointment.

Tattoos:

Dear Abby lies, or at least is very mistaken at times. There have been very few cases of tattoo pigment causing problems with MRI scans. However, there are a couple of reported cases of mild burns in the area of the tattoo. This is extremely rare and is likely associated with older, unusual pigments in high concentrations in the skin. The metals in some tattoo pigments are in a form that does not normally cause problems with MRIs, and normally should never cause a problem.

There is a slight exception with tattooed eyeliner. Because of the sensitivity of the area, and the high concentration of tattoo ink in the eyelid, it is not uncommon for people to report a slight warmness in the area. Normally this is easily controlled just by the application of wet cotton balls onto the lids.

If you do notice a burning or uncomfortable feeling in the area of the tattoo during and MRI scan, just tell the technologist.

It's worth noting that, in general, people involved in MRI procedures tend to be far less tolerant of body jewellery/mods than those working in other imaging procedures. This is likely due to the relative newness of the technology. I have had physicians insist that body jewellery will be heated to high temperatures by magnetic induction, even though they will happily scan people with hip implants. Of all medical imaging procedures, MRI is the one in which you are most likely to be given inaccurate information or refused a test because of body jewellery.

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