What is magnetic resonance imaging (MRI)?

Magnetic resonance imaging (MRI) is a type of scan used to get a detailed picture of the inside of your body. 

  • It uses strong magnetism, radio waves and a computer
  • It does not use radiation (X-rays).

MRI cannot diagnose prostate cancer on its own. You will usually need to have a prostate biopsy as well. 


  • Watch this video from Cancer Research UK to find out what it is like to have an MRI scan.

© Cancer Research UK [2002] All rights reserved. Information taken 21/03/23. Cancer Research UK are independent from Prostate Cancer Research.

Important things to know

Why do I need an MRI scan?

Doctors use MRI scanners to look for any suspicious areas in:

  • Your prostate
  • The area surrounding your prostate. 

If they think that cancer may be present, they may recommend you have a prostate biopsy. 

Frequently asked questions (FAQs) about MRI scans
  • A standard MRI scanner is a large, cylinder-shaped tube. You will be asked to lie on a table that then slides into the tube. 


Black man in MRI scanner


  • Some people can feel shut in (claustrophobic) when inside the tube. If you think you may have a problem, contact the radiography department, or tell your doctor. Your doctor may prescribe you some light sedation. This will help you to relax. 


  • You will not be able to go into an ‘open’-type MRI scanner. This is because the magnetic field strength is lower than in closed MRIs. This means they will not give a clear enough picture of your prostate. 


  • MRI scans can be very loud. You may be given some ear plugs or headphones to wear before going into the scanner. 
  • A multi-parametric MRI (mpMRI) works by producing more detailed pictures of your prostate than a normal MRI. This means that your healthcare team can:
    • See any suspicious areas more easily.
    • Decide whether you need to have a biopsy of your prostate.
    • Target biopsy needles more accurately. This can reduce the number of samples that are taken from your prostate at one time.
    • See if there are any suspicious areas outside your prostate. For example, in lymph nodes or bones in your pelvis. 


  • It is often done before you have a prostate biopsy. 


  • mpMRI is now the ‘gold standard’ recommended type of MRI. But it is not available in every hospital. You can talk to your doctor about mpMRI. 


  • Our services search tool (link will open in a new tab) will allow you to search for hospitals near you that offer mpMRI.


What do I need to do?

  • You may be asked to empty your bowels before your MRI. Your appointment letter should tell you about any preparation you need. 


  • Some metals interfere with the magnetic field of the MRI. They may damage some of your belongings. Before going to the MRI room, you will need to remove:
    • Jewellery 
    • Watches, including electronic watches and GPS trackers
    • Mobile phones
    • Body piercings
    • Removable dental devices such as, braces
    • Pens
    • Spectacles
    • Credit cards
    • Hearing aids.


  • The radiographer will go through a safety checklist with you before you can have your MRI. You need to tell them about any metalwork that you have inside your body. This includes:
    • Pacemakers
    • Cochlea implants
    • Surgical clips, coils, pins or plates 
    • Dental fillings or bridges
    • Any other metal fragments.


  • Having any of these devices does not necessarily mean you will not be able to have an MRI. If you got a leaflet after having an implanted device, it may mention MRI. If you have these leaflets, bring them with you to the scan.

What is contrast medium?

  • You may have to have an injection of special dye. This is called a contrast medium. 
  • This will give a clearer picture of your prostate. 
  • You may also be given an injection that will stop bowel movement. This is called Buscopan (hyoscine butylbromide). 
  • Before you have the injections, tell the radiographer about any:
    • Allergies that you have
    • Medical conditions that you have.
  • The radiographer will put a small tube into a vein on the back of your hand or in your arm. This is called a cannula. The radiographer willcannula in hand use this to inject the dye and the Buscopan. 


  • Your test results may take one-to-two weeks to come back. 


  • A radiologist will look at your scans and give them a score. 
  • You may hear your doctor talk about the Likert score or the PI-RADS score. 
  • These go from one-to-five and tell you how likely it is you have prostate cancer. This will help your doctor decide what to do next. 
Pi-Rads score

About this information

  • This information was published in March 2023. We will revise it in March 2024.
  • References and bibliography available on request.
  • If you want to reproduce this content, please see our Reproducing Our Content page.

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