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. This can help your doctor see if there is any cancer inside your prostate, and how quickly any cancer is likely to grow. In other hospitals, you may have a biopsy first, followed by an MRI scan.

If you had an MRI scan before your biopsy that showed your cancer hasn't spread outside the prostate, you may not need another MRI scan. But if your doctor thinks your cancer may have spread, or if you didn't have an MRI scan before your biopsy, you may have one. It will show whether the cancer has spread outside the prostate and where it has spread to. It will also help your doctor to work out the most suitable treatment options for you.

If you’ve recently had a biopsy, you may need to wait four to six weeks before you have an MRI scan. This is because the biopsy can cause bruising and bleeding around the prostate, which could affect the scan results.

Read our information on what MRI scans involve and what the results mean.

CT scan

A CT (computerised tomography) scan can show whether the cancer has spread outside the prostate, for example to the lymph nodes or nearby bones. Lymph nodes are part of your immune system and are found throughout your body. The lymph nodes near the prostate are a common place for prostate cancer to spread to. The scan results will help your doctor to work out the most suitable treatment options for you.

Your hospital might ask you not to eat or drink for a few hours before the scan. You’ll need to take off any jewellery or metal items, as these can affect the images.

At your scan appointment, you’ll be given a special dye to help the doctor see the prostate and other organs more clearly on the scan. It’s not radioactive. Most hospitals give you the dye as an injection. But some give the dye as a drink. The dye can give you a warm feeling and you might feel like you need to go to the toilet.

Before your scan appointment let your doctor know if you already know you are allergic to the dye, you have any other allergies, or you are taking the drug metformin for diabetes.

The CT scanner is shaped like a large doughnut. You will lie on a table that moves slowly through the hole in the middle of the scanner. The radiographer will leave the room but you’ll be able to speak to them through an intercom, and they can see you at all times. You will need to keep still, and you might be asked to hold your breath for short periods. The scan will take up to 20 minutes.

Bone scan

A bone scan can show whether any cancer cells have spread to your bones, which is a common place for prostate cancer to spread to.

Tell your doctor or nurse if you have arthritis or have ever had any broken bones or surgery to the bones, as these will also show up on the scan.

You might be asked to drink plenty of fluids before and after the scan. A small amount of dye is injected into a vein in your arm and travels around your body. If there is any cancer in the bones, the dye will collect in these areas and show up on the scan. It takes two to four hours for the dye to travel around your body and collect in your bones so you’ll need to wait a while before you have the scan.

You will lie on a table while the scanner moves very slowly down your body taking pictures. This takes around 30 minutes.

The doctor will look at the scan images to see if there is any cancer in your bones. Areas where the dye has collected may be cancer – these are sometimes called ‘hot spots’. You may need to have X-rays of any ‘hot spots’ to check if they are cancer. If it’s still not clear, you may need an MRI scan or, very occasionally, a bone biopsy.

The dye used for a bone scan is safe but it is radioactive. So you should try to avoid close contact with children and pregnant women for up to 24 hours after the scan. And make sure you flush straight away after using the toilet for 24 hours after the scan.

PET scan

At some hospitals, you may be offered a PET (positron emission tomography) scan. There are two main types - choline PET and PSMA PET.

A PET scan can be used to check if cancer has spread to the bone, lymph nodes and other tissues.

It is normally used to see if your cancer has come back after treatment, rather than when you are first diagnosed.

Getting my scan results

Your doctor or nurse will tell you how long it will take for the results of all the tests to come back. It’s usually around two weeks.

Your doctor will use your scan results to work out the stage of your cancer – in other words, how far it has spread. This is usually recorded using the TNM (Tumour-Nodes-Metastases) system.

  • The T stage shows how far the cancer has spread in and around the prostate.
  • The N stage shows whether the cancer has spread to the lymph nodes.
  • The M stage shows whether the cancer has spread (metastasised) to other parts of the body.

T stage

The T stage shows how far the cancer has spread in and around the prostate. A DRE or MRI scan is usually used to find out the T stage, and sometimes a CT scan.

T1 prostate cancer

The cancer can’t be felt during a DRE or seen on scans, and can only be seen by looking at your biopsy sample under a microscope.

T2 prostate cancer

The cancer can be felt during a DRE or seen on scans, but is still contained inside the prostate.

  • T2a The cancer is in half of one side (lobe) of the prostate, or less.
  • T2b The cancer is in more than half of one of the lobes, but not in both lobes of the prostate.
  • T2c The cancer is in both lobes but is still inside the prostate.

T3 prostate cancer

The cancer can be felt during a DRE or seen breaking through the outer layer (capsule) of the prostate.

  • T3a The cancer has broken through the outer layer of the prostate, but has not spread to the seminal vesicles (which produce and store some of the fluid in semen).
  • T3b The cancer has spread to the seminal vesicles.

T4 prostate cancer

The cancer has spread to nearby organs, such as the bladder, back passage or pelvic wall.

N stage

The N stage shows whether the cancer has spread to the lymph nodes near the prostate. Lymph nodes are part of your immune system and are found throughout your body. The lymph nodes near the prostate are a common place for prostate cancer to spread to.

An MRI scan or CT scan is used to find out your N stage.

The possible N stages are:

  • NX The lymph nodes were not looked at, or the scans were unclear.
  • N0 No cancer can be seen in the lymph nodes.
  • N1 The lymph nodes contain cancer.

If your scans suggest that your cancer has spread to the lymph nodes (N1), you will be diagnosed with either locally advanced or advanced prostate cancer. This will depend on whether the cancer has spread to other parts of the body.

M stage

The M stage shows whether the cancer has spread (metastasised) to other parts of the body, such as the bones. A bone scan is usually used to find out your M stage. Your doctor may offer you a bone scan if they think your cancer may have spread. You might not need a bone scan if the result is unlikely to affect your treatment options.

The possible M stages are:

  • MX The spread of the cancer wasn’t looked at, or the scans were unclear.
  • M0 The cancer hasn’t spread to other parts of the body.
  • M1 The cancer has spread to other parts of the body.

If you have a bone scan and it shows your cancer has spread to other parts of your body (M1), you will be diagnosed with advanced prostate cancer.

What do my scan results mean?

Your TNM stage is used to work out if your cancer is localised, locally advanced or advanced. This can help your doctor see how far it has spread and which treatment might be suitable for you.

Localised prostate cancer

Cancer that's contained inside the prostate. Sometimes called early prostate cancer. Possible TNM stages are:

  • T stage: T1 or T2
  • N stage: N0 or NX
  • M stage: M0 or MX.

Locally advanced prostate cancer

Cancer that's started to break out of the prostate, or has spread to the area just outside it. Possible TNM stages are:

  • T stage: T1 or T2
  • N stage: N1
  • M stage: M0

or

  • T stage: T3 or T4
  • N stage: N0 or N1
  • M stage: M0.

Advanced prostate cancer

Cancer that's spread from the prostate to other parts of the body. Also known as metastatic prostate cancer. Possible TNM stages are:

  • T stage: any T stage
  • N stage: any N stage
  • M stage: M1.

References

Updated: January 2019 | Due for review: January 2021

  • List of references  

    • Haffner J, Lemaitre L, Puech P, Haber G-P, Leroy X, Jones JS, et al. Role of magnetic resonance imaging before initial biopsy: comparison of magnetic resonance imaging-targeted and systematic biopsy for significant prostate cancer detection. BJU International. 2011 Oct 1;108(8b):E171–8.
    • Kirkham APS, Emberton M, Allen C. How good is MRI at detecting and characterising cancer within the prostate? Eur Urol. 2006 Dec;50(6):1163–74; discussion 1175.
    • National Institute for Health and Care Excellence. Prostate Cancer: diagnosis and treatment. Full guideline 175. 2014.