MRI scan

How an MRI scan works

During a magnetic resonance imaging (MRI) scan, you lie in a strong magnetic field and radio-frequency waves are directed at your body. This produces detailed images of the inside of your body.

Most of the human body is made up of water molecules, which consist of hydrogen and oxygen atoms. At the centre of each hydrogen atom there is an even smaller particle called a proton. Protons are like tiny magnets and are very sensitive to magnetic fields.


Short bursts of radio waves are then sent to certain areas of the body, knocking the protons out of alignment. When the radio waves are turned off, the protons realign and in doing so send out radio signals, which are picked up by receivers.



Last updated: 14 February 2014

Continue to next section: How an MRI scan is performed