The first thing we need to understand is what MRI actually is and why you may need an MRI scan some day. MRI stands for Magnetic Resonance Imaging, which is the process used for creating pictures or images of the inside of our bodies in the form of very thin “slices”. The images created are used to diagnose more obscure medical maladies such as multiple sclerosis, infection of the brain or spine, tendonitis and even the early stages of stroke to mention just a few. The two major functions of an MRI machine is a powerful magnetic field and radio frequency pulses, which used together send signals from the MRI machine to our body and then back to a computer, which then converts mathematical data into an image. (For more detailed information on how MRI works, I recommend this informative howstuffworks.com MRI guide)
It is the powerful magnetic force that creates a concern, not only to those who are tattooed, but also to anyone with metal objects in their bodies such as implants (dental or otherwise), pacemakers or even metal fragments. The magnetic force of an MRI machine is so strong, even the “weakest” machine used (about 0.5-tesla) is 10,000 times the strength of the Earth’s magnetic field. Even small metal objects such as paperclips or keys can become projectile weapons if left in an MRI room during a scan.
So, what does all of this have to do with tattoos? Well, it appears that about 20 years ago and further, tattoo ink was sometimes comprised of small fragments of metal as well as other ingredients. This was long before tattoos were ever regulated and before more serious thought was given as to the safety of tattoo ink ingredients. Some MRI patients who have had tattoos that dated back far enough to have received ink that contained metal bits have reported slight discomfort to severe pain during an MRI scan.
It is purported that the reason for this was that the magnetic force pulled on the metallic fragments so violently that it caused a burning sensation in the location of the tattoo. I have heard some theorize that this may have been caused by built up friction between the particles, and some say that the magnetic force was actually tearing at the skin as the fragments were pulled and attempted to actually break away from the skin. I don’t know which, if either, is true; however, even if there is no pain at all, these fragments can cause artifacts, which is the technical term used for distortions in MRI scans. Artifacts can render a scanned image useless, requiring that the procedure be done again or even an alternate procedure be used to acquire accurate information. So, at the very least, you could be stuck with a very expensive bill for nothing -if, of course, your tattoo actually contains these metal particles.
How can you know if your tattoo contains metal? Well, there is no really easy way to know for sure unless you have access to a very high-powered metal detector. But don’t fret – if your tattoo was obtained within the past 20 years you are almost assured that this is not going to be an issue for you. Even if your tattoo is older than 20 years old, that doesn’t mean the ink absolutely contained metal. And even if it did contain metal, that does not mean you absolutely will have a problem with getting an MRI. If you find yourself at this juncture, it will be best for you to inform your doctor of your concerns and let them help you make an informed decision. Remember that there are always alternatives to MRI – people with pacemakers and metal implants (among other things) also have to find other diagnostic methods. Your doctor can help you decide if you might be at risk and, if so, what alternate options are available to you.