How does an MRI machine work?

An MRI takes pictures of your brain using magnets.

What is a magnet?

Basically, a magnet is anything that has a magnetic field or magnetism. Magnetism is caused by a moving electrical charge. One of the smallest magnets is an atom. The electrons in an atom, which have an electrical charge, move in a circle around the center of the atom. This spinning movement produces magnetism—so each atom is like a little magnet.

All the cells in your body are made-up of atoms - so you have millions of little magnets in you!

How does a magnet take a picture?

The magnet in the MRI scanner is like the magnets in your body, but it is stronger. The MRI magnet works with your magnets to make a picture of your brain. The little magnets in different parts of your brain spin at different speeds depending on how much water is there. The MRI magnet colors a black and white picture of all the spinning magnets in your brain - the faster the magnets spin, the darker the color. So we get a nice black & white picture of your brain without a camera or film—just magnets.

Why does the MRI scanner make that noise?

The magnet makes a lot of pictures of your brain very fast. Every time it makes a picture, it makes a “ping” sound. All those pinging sounds are like the “clicks” a camera makes when it takes a picture. Because the MRI makes so many pictures, it is noisy. We give you ear plugs to make it not so noisy.

Why do I have to lie so still?

If you are moving around, then your magnets are moving too. This will make the picture of your brain blurry - just like with a camera. So it is important not to move at all while you are in the scanner. You will be in the scanner for about half an hour with the door closed. We will be able to see you from the other room but you will be the only one in the scanner.