MRI: Magnetic Resonance Imaging

What is Magnetic Resonance Imaging (MRI)?

Magnetic Resonance Imaging (MRI) uses a very strong magnet and radiofrequency waves to build up an image of the inside of your body. MRI does not use ionising radiation. This means MRI is not thought to lead to an increased risk of cancer. MRI is very good for looking at soft tissue within the body.

However, there are risks of the magnetic field such as if you have metal implants or some pacemakers. The Radiographer will go through a safety checklist with you before the MRI starts to make sure that there are no issues.

What do I need to know?

This film tells you about how MRI works and what the risks are.

Take away points

  • MRI does not use ionising radiation and so is not thought to increase your risk of cancer.

  • MRI can be very loud and the scanner is quite close to the patient.

  • Some people find this very hard, if you think you may struggle let the person carrying out your exam know.

  • You will be able to stop the scan at any time.

  • You will not be able to take in any metal objects such as watches, jewellery etc.

  • Some tattoos can heat up due to the MRI scan. If you feel anything please let the person carrying out the scan know.

  • Tell the person carrying out your scan if you have any implants.

Gadolinium contrast

Sometimes a clear liquid is injected into your veins during the scan. This will only be used if needed and is not right for everyone, for example if you have had kidney issues. The Radiographer will check before the scan to make sure that it is suitable for you.

There are some mild, short-lived side affects connected with the use of gadolinium for example:

  • pain at the site of injection

  • change in sensation (feeling)

  • itching, rashes and changes in skin sensations

  • vomiting

  • headaches

Extreme allergic reactions are rare but immediate medical attention should be sought.


  • MRI does not use X-rays (ionising radiation) and so is not related to an increased lifetime risk of cancer.

  • MRI is not right for every condition and your doctor will discuss whether it is suitable for you.

  • Let the radiographer know if you are, or may be, pregnant when you come to your scan.

  • Let the radiographer know if you feel any heating or discomfort during your scan.

  • If you have had contrast and experience a allergic reaction seek medical help immediately.