A young person's guide to

MRI Scans

Magnetic Resonance Imaging (MRI) is one of the main technologies we use to look inside our bodies. It's an excellent way to diagnose multiple sclerosis, brain tumors, torn ligaments, tendonitis, cancer and strokes, and many others.

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Imaging specialist Dr Erik O'Hanlon explains how an MRI machine works.

The heart of an MRI is basically just a strong magnet and a radio transmitter and receiver, plus a lot of electronics to coordinate their operation. 

How does MRI work?

How does MRI work?

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An MRI scanner contains large magnetic coils made from superconducting magnets

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So when you enter an MRI machine, it's like entering the field of a gigantic magnet

To simplify our explanations, we're going to represent the MRI scanner as a gigantic magnet

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Your body enters the magnetic field of the MRI scanner

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Hydrogen protons in your body  line up with the magnetic field 

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Radiofrequency pulse excites hydrogen atoms

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Then turn off the radiofrequency pulse. Protons are left with all this extra energy

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MRI Scanner detects the energy released by the protons

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By measuring the time taken to release energy, the type of tissue can be determined and a picture generated

Is that all there is to it?

Well, that's the quick version. As Erik says, the full physics behind MRI imaging is a bit more complex. For a more detailed explanation listen to another neuroscientist in the Guardian's Science Weekly.

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Why would you get an MRI scan and how is it different from other scans like X-rays?

You may be familiar with other ways of creating images of our bodies like X-rays which are great at showing bones. An MRI is excellent at showing details of soft tissues in our body such as muscles, ligaments, organs and so on.