MRI: the short version


A volunteer about to have his brain scanned

What is MRI?

Magnetic Resonance Imaging.


A magnetic resonance scanner (right) is a really neat piece of equipment that allows us to safely examine many aspects of the body's structure and function. It does not use harmful radiation and so is ideally suited to research using normal volunteers.

What creates the images?

The scanner tunes into the behaviour of water when it is in a strong magnetic field. Since water is a major part of humans, we can use this behaviour to create medical images.

How does the scanner work?

When someone is placed inside to magnetic scanner, the behaviour of the water in their bodies alters very slightly. This is not dangerous and you won't notice it. The effect can be exaggerated by directing radio-waves at the part of the body we are interested in seeing. When the radio waves are turned off, the water goes back to normal and we can pick up on that change.

More than just anatomy...

We can examine lots of things with the scanner, including:

Structural: Obtain detailed 3D pictures of the human body

Functional: See the amount of oxygen your brain uses

Spectroscopy: Detect different chemicals in the body

What does an MRI examination involve?

We will show you the scanner and make sure you have no metal objects in or around you. If you wear glasses these will need to be removed. You can wear contact lenses but not if they are tinted. You will be asked to lie on a bed that will be moved into the scanner, after giving you some ear protectors. The scanner makes a loud noise when working, but you can listen to music for some of the time.

We are able to communicate through a two-way intercom during the scan. We provide you with an emergency call button with which you can let us know if you want to stop the scan at any point.

Important exclusions

Unfortunately you cannot have a scan if you have any of the following:

  • A heart pacemaker
  • Surgical clips or metal objects in your head
  • Neuro-electrical implants
  • Metal objects in your body
  • Severe claustrophobia


As the title suggests, this was just to give you a brief introduction into MRI and what a scan would involve, but if you'd like to read about it in more detail, take a look at MRI: the long version.


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