MRI scan

An MRI (magnetic resonance imaging) scan uses magnets to create a detailed picture of your prostate and the surrounding tissues.

In many hospitals you may have a special type of MRI scan, called a multi-parametric MRI (mpMRI) scan, before having a biopsy. In some hospitals, you may have a biopsy first, followed by an MRI scan to see if any cancer found inside the prostate has spread.

Not all hospitals are able to do mpMRI scans before biopsy, but your doctor may be able to refer you to one that does.

An MRI scan may not be possible if you have a pacemaker or other metal inside your body.

What are the advantages and disadvantages of having an MRI scan before a biopsy?

Advantages

• It can give your doctor information about how likely it is that you have cancer in your prostate.
• It’s less likely than a biopsy to pick up a slow-growing cancer. This means you are less likely to have a biopsy and treatments that could have life-changing side effects if your cancer is unlikely to cause you any problems in your lifetime. Some side effects include severe infections and long lasting urinary or sexual problems.
• It can help your doctor decide if you need a biopsy – if there’s nothing unusual on the scans, this means you’re unlikely to have prostate cancer that needs to be treated. You may be able to avoid having a biopsy, and its possible side effects.
• If you do need a biopsy, your doctor can use the scan images to decide which parts of the prostate to take samples from.
• If your biopsy finds cancer, you probably won’t need another scan to check if it has spread, as the doctor can get this information from your first MRI scan. This means you can start talking about suitable treatments as soon as you get your biopsy results.

Disadvantages

• Being in the MRI machine can be unpleasant if you don’t like closed or small spaces (claustrophobia).
• Some men are given an injection of dye during the scan – this can sometimes cause mild side effects.

What does an MRI scan involve?

Before the scan the doctor or nurse will ask questions about your health. As the scan uses magnets, they will ask whether you have any metal in your body such as implants or fragments that could be attracted to the magnet. They will decide if you can't have an MRI or if there are any changes needed to make sure the MRI is as safe as possible for you.  For example, if you have a pacemaker for your heart you may not be able to have an MRI scan. You’ll also need to take off any jewellery or metal items. If you use patches on your skin such as pain medication, you should ask the doctor if this should be removed for the MRI scan.

You will lie very still on a table, which will move slowly into the scanner which is shaped like a doughnut or a long tunnel. If you don’t like closed or small spaces (claustrophobia), tell your radiographer (the person who takes the images) and they may be able to suggest some ways that could help you feel more comfortable in the scanner.

The radiographer might give you an injection of a dye during the scan. The dye helps them see the prostate and other organs more clearly on the scan. It is usually safe, but can sometimes cause problems if you:

• have kidney problems
• have asthma
• are allergic to the dye or have any other allergies.

Let the radiographer know if you have any of these.

The scan takes 30 to 40 minutes. The machine won’t touch you but it is very noisy and you might feel warm. The radiographer will leave the room but you’ll be able to speak to them through an intercom, and will wear earplugs or ear defenders. You may also be able to listen to music through headphones.

Getting the results

Your MRI scan images will be looked at by a specialist called a radiologist, who specialises in diagnosing health problems using X-rays and scans. The radiologist will give the images of your prostate a score from 1 to 5. You may hear this called your PI-RADS (Prostate Imaging – Reporting and Data System) score or your Likert score. It tells your doctor how likely it is that you have cancer inside your prostate.

PI-RADS and Likert scores have the same values, and your score will be between 1 and 5.

• PIRADS or Likert score 1 It’s very unlikely that you have prostate cancer that needs to be treated
• PIRADS or Likert score 2 It’s unlikely that you have prostate cancer that needs to be treated.
• PIRADS or Likert score 3 It isn’t possible to tell from the scan whether you have prostate cancer that needs to be treated – you may hear this called a borderline result.
• PIRADS or Likert score 4 It’s likely that you have prostate cancer that needs to be treated.
• PIRADS or Likert score 5 It’s very likely that you have prostate cancer that needs to be treated.

If your PI-RADS or Likert score is 1 or 2

This means you’re unlikely to have prostate cancer that needs to be treated. Your doctor would discuss advantages and disadvantages of having a further biopsy to help make a shared decision with you. This would include talking through your individual risk factors such as age, ethnicity or family history.

Together, you and your doctor may decide that you don’t need to have a biopsy. Your doctor may suggest you have regular PSA tests so that any changes in your PSA level are picked up early. You’ll also be offered treatment for any urinary symptoms.

Or you and your doctor can decide for you to have a prostate biopsy as it will help confirm if there is no cancer that needs to be treated.

If your PI-RADS or Likert score is 3 or more

You’ll usually be offered a prostate biopsy to find out whether you have cancer.

References

Updated June 2022 | To be reviewed January 2025