- 5 min read
What are imaging tests?
Imaging tests can often provide additional information on what is going on in your body alongside blood tests (like PSA testing) and physical examinations (such as a digital rectal examination). They take detailed pictures of certain areas in your body using different forms of energy, such as x-ray radiation, ultrasound waves, magnetic fields, radio waves and radioactive substances.
Imaging tests are used to help detect abnormalities that could be cancer and to guide disease treatment after cancer has been diagnosed from a biopsy. They may help identify the size and location of cancer and whether the cancer has spread (called staging).
Your doctor should talk to you about the imaging tests they recommend for your situation. They can then use the results to decide on your next best steps. This section of your toolkit will help you understand the different imaging tests your doctor may recommend.
The types of imaging tests used in prostate cancer
In prostate cancer, these are the types of imaging tests that you may have:
Imaging tests can be expensive. Make sure you know what costs are involved.
Ask your urologist about their fees – how much is covered by Medicare and what you will need to pay.
Ask your health insurer what costs they will cover and what you will need to pay.
- Magnetic resonance imaging (MRI)
- Computerised tomographic (CT) scan
- Whole-body bone scan
- PSMA-PET/CT
If you have questions or concerns about any of these tests, you can ask your doctor or talk to a PCFA nurse.
Magnetic resonance imaging (MRI)
MRI uses high-powered magnetic fields and radio waves to create a three-dimensional image of internal regions of your body. It can be used to check any part of your body for abnormalities. In prostate cancer management, MRI can be used before diagnosis to determine your risk of cancer and during treatment for the disease.
How is MRI used before a diagnosis of prostate cancer?
If your PSA tests and/or digital rectal examination results show there is a chance you may have prostate cancer, your urologist may recommend MRI. In most cases the type of MRI you will be given is called multiparametric MRI (mpMRI). This is a newer, more accurate type of MRI which is the preferred type of MRI used for prostate cancer risk assessment in Australia. It combines the results of several different scans to get clearer, more detailed images of your prostate from all angles (three-dimensional images). The images will show any suspicious areas – where they are in your prostate and how big they are. It will also show if the cancer has spread outside of your prostate into the surrounding areas.
Your doctor can analyse the mpMRI images using a sophisticated system called the Prostate Imaging – Reporting and Data System (PI-RADS) to work out your PI-RADS score. This score gives you an idea of your risk that a harmful cancer is present in your prostate as follows:
- PI-RADS 1: very low risk
- PI-RADS 2: low risk
- PI-RADS 3: intermediate risk
- PI-RADS 4: high risk
- PI-RADS 5: very high risk
A biopsy is the only way prostate cancer can be diagnosed for certain. MRI helps you know if there is a chance you might have cancer.
Your urologist will consider the information from your MRI as well as your PSA test and digital rectal examination results to determine if you need to have a prostate biopsy to diagnose prostate cancer. If you do have a prostate biopsy, the MRI images will help your urologist to know what part of your prostate to take the samples from.
How is MRI used during prostate cancer treatment?
During prostate cancer treatment MRI can be used
- to monitor your cancer for any changes if you are being treated with active surveillance.
- for MRI guided radiation therapy (MR-Linac) to treat your cancer more precisely
What happens during MRI?
When you have MRI, you will have it as an outpatient at a hospital or at an imaging clinic. You won’t need to be admitted to hospital.
To make your prostate easier to see on the scans, a special dye may be injected into your arm. For the MRI, you will lie on a special bed that will move slowly into a long, narrow tunnel.
It is vital that you tell your doctor if you have any metal or medical devices in you body before having MRI
While lying still within the machine, scans of your prostate area are taken. It’s very noisy so you will be given headphones, but it’s painless. However, if you suffer from claustrophobia, it is a good idea to discuss this with your doctor before having MRI as they can prescribe sedative medications to make the procedure easier for you.
As MRI uses magnetic fields, it is also important you tell your doctor if you have any metallic objects in your body (for example, shrapnel or metal pieces from a previous injury, or surgical clips, pins, screws or plates) or medical devices (such as a pacemaker or cochlear implant) in your body, or if you have had joint surgery. It is not safe to have MRI if you have certain metal devices in your body.
Computerised tomographic (CT) scan
A CT scan uses advanced x-ray technology to give detailed 3D images of inside your body. It can help to see what’s going on in your prostate and the surrounding organs and tissues and can show where cancer is located and if it has spread. If the cancer has spread it may be seen as abnormal areas, such as enlarged lymph nodes or growths in other parts of the body.
What happens during a CT scan?
Like an MRI, you lie still on a special bed for a CT scan. The bed will move slowly under a large, doughnut shaped machine. Unlike the MRI, it is not a long, narrow tunnel. You may have an injection of dye to make the images of your prostate and abdomen easier to see, but overall, the CT scan is painless.
Whole-body bone scan
A bone scan may be useful for checking if prostate cancer has spread into your bones. If there are cancer cells within your bones the scan may be positive. However, a positive bone scan may be due to other causes, such as an old fracture or benign (not cancer) inflammatory conditions, like arthritis.
Bone scans are mostly used to check for advanced prostate cancer or to monitor cancer progress.
What does a bone scan involve?
For a bone scan, a tiny amount of radioactive substance is injected into a vein in your arm. It is called a whole-body scan as the substance will travel throughout your body and may settle in some of your bones.
After a few hours, you will be scanned by a machine that detects the radioactive substance, as it shows up differently in normal and diseased bone. This scan is also painless, and the substance will leave your body in a few hours.
PSMA-PET/CT
The PSMA-PET/CT scan is a newer technology that is a very sensitive and accurate way to see and find prostate cancer wherever it is in the body.
The PSMA-PET/CT combines the results of two tests:
- PSMA-PET uses a radioactive material to light up certain areas of your body
- A CT scan gives 3D images of the insides of your body from different angles
PSMA is a protein that attaches to the surface of prostate cancer cells and is lit up when seen on a PSMA PET scan.
For the PSMA-PET part of the scan, a weakly radioactive material will be injected into your blood. This material travels throughout your body and attaches to a protein found on the outside of prostate cells, called prostate specific membrane antigen or PSMA.
You will then have a PET (positron emission tomography) scan and any cancer cells in your body will show up brightly on the scan.
Combining the results from the CT and PET scans into one image makes this very accurate at finding prostate cancer in the body. It can detect very small amounts of cancer that other scans may miss and is especially important for men with high-risk prostate cancer.
In July 2022, the PSMA-PET/CT was listed under Medicare, so the cost is rebated, meaning it will now cost you less to have this imaging test.
It is best to talk to your urologist about whether this scan is recommended for you, but you can also read more information on the role of PSMA-PET/CT and its uses in prostate cancer.
Key points
- There are multiple imaging tests used in prostate cancer detection and planning of treatment.
- A MRI or mpMRI may be recommended after initial test results show a risk of prostate cancer.
- CT and bone scans can be used to detect cancer spread but can have less accuracy.
- The PSMA-PET/CT scan is a newer imaging test that is very accurate at finding prostate cancer cells in the body, and is especially useful in diagnosis or monitoring. men at high-risk.
