The news that your child needs an MRI for the first time can sometimes make them feel nervous or scared. It’s hard for children to imagine how something they’ve never experienced might work; explaining as much as we can to them, in an age-appropriate way, can give them a little more confidence ahead of their appointment.
What Is an MRI?
MRI stands for “magnetic resonance imaging.” Using strong magnets and radio waves, the inside of the body can be viewed without poking you or performing surgery, and without the radiation of an x-ray. MRI gives us detailed pictures of the soft tissues of the body like your brain, your spinal cord, and your muscles. It’s like a superpower to see through you! These images can be used to diagnose disease and guide treatment.
How Long Does an MRI Take?
We joke that they are always 5 minutes longer than you thought. Most MRI exams are approximately 45 minutes long, which can feel like a long time inside the machine! Each sequence, which produces a set of images, is about 5 minutes long. That’s why the technologist keeps telling you “Hold still for 5 more minutes please.”
Why Is the MRI Machine Shaped like a Donut?
The MRI is shaped like a donut because the machine is actually a giant magnet! It’s on all the time. It is a super conducting solenoid magnet. (Solenoid just means a cylindrical coil of wire.) The solenoid magnet makes a very uniform magnetic field: it’s the same anywhere inside the donut. That is how you get the pictures of all the soft tissues on the inside of your body.
What Is the “Bird Chirping” Sound When You Get near the MRI Machine?
That sound is a helium re-condensing pump which takes the boiled-off helium gas and re-condenses and cools it to liquid helium. It’s the same helium you fill balloons with; in fact, there is enough helium in each MRI scanner to fill approximately 86,000 party balloons!
Why Do You Need Helium?
The helium keeps the MRI magnet’s wires working properly by keeping them extremely cold. This allows the magnet to be stronger.
Why Is It So Loud?
MRIs make loud buzzing, beeping, or banging noises when acquiring images. That’s why you will be asked to wear ear plugs or earmuffs. As electrical current runs through the magnetic field gradient coils in different sequences, it interacts with the main magnetic field. That causes the gradient coils to vibrate, which is noisy. You can actually identify which MRI sequence is being run by its characteristic sounds.
Why Do I Feel Warm?
Some patients feel warm as the machine takes their images because the MRI machine delivers energy to the body to get the picture. Long scans (which deliver more energy) and larger patients (who dissipate heat more slowly) tend to feel this warmth most.
Do I Really Have to Hold Still?
YES! You need to be a statue. Even a small amount of motion can ruin a set of images, or at the least make them blurry. If you must move to scratch your nose or wiggle your toes, do it when the machine stops making noise. That way you’ll be moving when the machine is not taking any pictures.
Can I Watch a Movie?
Yes, you can watch a movie or TV show or listen to music during most MRIs. You will have special earplugs that the sound is piped through AND special goggles so you can see the screen. But unfortunately, MRI exams are timed perfectly to end when the movie gets to the best part.
Why Do I Have to Change Clothes?
Some clothing has metal such as zippers, snaps, pins, or even metallic threads that disrupt the MRI by creating artifacts (errors on the image), heat up and burn the patient or, rarely (if not attached), fly through the room into the magnet. It is easier to have patients change than closely inspect all clothing. Many patients don’t know they have metal or electrical conductors even if we did ask. Do you have metal threads in your underwear?
Why Do They Ask Me and My Parents All the Safety Questions about Medical Implants and Surgery so Many Times?
Safety screening is taken seriously in MRI. It is important to know what is being placed in the MRI machine and the MRI room and how it will interact with the MRI environment. Implanted devices can cause image distortion, the device may malfunction, or the device may move in the strong magnetic field.
Why Can’t Metal Objects Come into the MRI Room? What If I Hold onto Them Tightly?
The strong magnet will pull metal objects into the scanner. The magnetic field gets stronger the closer you get to the magnet. If you feel the force pulling on a metal object it is too late; as the object moves closer to the magnet the force rapidly increases beyond the strength of any human.
Why Do You Make Sure I Have Used the Bathroom?
Just to make sure you are empty. It is easier to hold still like a statue if you are empty. If you think you are empty now, you may not be an hour from now.
Aaron McAllister, MS MD, is a pediatric neuroradiologist in the Department of Radiology at Nationwide Children’s Hospital, providing world class care to patients.
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