MRI scans

Magnetic resonance imaging (MRI) is a type of scan used to diagnoe health conditions that affect organs, tissue and bone.

MRI scanners use strong magnetic fields and radio waves to produce detailed images of the inside of the body. 

An MRI scanner is a large tube that contains a series of powerful magnets. You lie inside the tube during the scan.

It can be used to investigate almost any part of the body including the:

• brain and spinal cord
• bones and joints
• breasts
• heart and blood vessles
• internal organs, such as the lungs and liver.

You lie on a flat bed which is moved into the scanning tube. Depending on the part of your body being scanned, you will be moved into the scanner either head first or feet first.

The MRI scanner is controlled by a computer which is in a different room from the scanner. This is to keep it away from the magnetic field generated by the scanner. 

A radiographer will operate the computer, this is someone who is trained in carrying out x-rays and similar procedures. You will be able to talk to them through an intercom and they will be able to see you on a TV moniter throughout the scan.

At certain points during the scan, the scanner will make a loud clicking sound, this is the magnets being turned on and off. You will be given earplugs or headphones to wear. You have to keep still during the scan. It will last between 15 and 90 minutes, depending on the area being scanned.

The radiowaves in the scanner cause hydrogen/protons in body tissues to line up parallel to each other. The waves knock them out of alignment and when they realign they make radio signals. They are picked up by the scanner and converted by the computer into an image.

An MRI scan is a painless and harmless procedure. You may experience a slight sense of claaustrophobia when you are inside the scanner. Unlike x-rays, MRI scans do not involve exposing the body to radiation. This means that people who may be vulnerable to the effects of radiation, such as pregnant women and babies, can safely use them.

However, not everyone can have an MRI scan. They're not recommended for people who have certain types of implants fitted, such as a pacemaker.