Below we look at how imaging tests, including x-rays, mammograms, ultrasounds, CT scans, PET-CT scans, bone scans and MRI scans, can be used to diagnose for cancer.
Common imaging tests
Imaging tests are used to take pictures of the inside of your body. They can be used to:
- look for cancer in its early stages when a person has no symptoms (screening scans, e.g. mammogram)
- look for a lump (tumour) if a person has symptoms and predict if it is likely to be cancer
- show where the tumour is and how far it has spread
- plan treatment
- see how treatment is working
- find out if cancer has come back after treatment.
How it works
Uses low-energy beams of radiation to create images of parts of the body, such as bones and the chest.
How long
10-30 minutes.
What happens
You hold still in front of or on a machine while the images are taken; you might be injected with a dye (contrast) to improve the image.
Special notes
Painless; the tiny dose of radiation will not make you give off radiation.
How it works
Uses a low-dose x-ray to create an image of the inside of the breast.
How long
10-30 minutes.
What happens
Your breast is placed between 2 x-ray plates, which press together firmly to spread the breast tissue.
Special notes
Can be briefly uncomfortable.
How it works
Uses soundwaves that echo when they meet something solid, such as an organ or tumour; a computer turns the soundwaves into a picture of the inside of the body.
How long
10-20 minutes.
What happens
A cool gel is spread on your skin and a handheld device called a transducer sends out the soundwaves as it is moved across the area; some transducers are wands that can be inserted in a body cavity.
Special notes
Usually painless, but can be uncomfortable.
How it works
Uses x-ray beams and a computer to create detailed pictures of the inside of the body; the scanner is large and round like a doughnut.
How long
Up to 30 minutes.
What happens
Before the scan, you may be given a drink or injected with a dye (contrast) to make the pictures clearer; you lie still on a table that moves in and out of the scanner.
Special notes
Painless; the dye may make you feel hot all over and leave a bitter taste in your mouth.
What is a CT scan and how is it used to diagnose cancer? Watch the video to find out.
How it works
Uses a magnet and radio waves to take detailed pictures of an area of the body.
How long
30-90 minutes.
What happens
Dye (contrast) may be injected into a vein to make the images clearer; you lie on a table that slides into a narrow metal cylinder that is open at both ends; the scan is noisy, so you will often be given earplugs or headphones.
Special notes
Let the medical team know if you feel anxious, you may be offered medicine to help you relax; let your medical team know if you have a pacemaker or any other metallic object in your body as you may not be able to have an MRI scan, although some newer devices are safe to go into the scanner.
What is an MRI and how is it used to diagnose cancer? Watch the video to find out.
How it works
Uses a low-dose radioactive solution to measure cell activity in different parts of the body; when combined with a CT scan it provides more detailed information about the cancer.
How long
About 2 hours.
What happens
You are injected in the arm with a small amount of radioactive solution, wait 30–90 minutes for it to move through your body, and then have the scan; cancer cells take up more of the solution than normal cells do and light up on the scan.
Special notes
The solution leaves your body in urine after a few hours; you may be told to avoid children and pregnant women for a number of hours.
What is a PET scan and how is it used to diagnose cancer? Watch this video to find out.
How it works
Uses radioactive dye to show any abnormal bone growth.
How long
Several hours.
What happens
You are injected in the arm with a small amount of radioactive dye, wait 2–3 hours for it to move through your bloodstream to the bones, then your body is scanned; a larger amount of dye will usually show up in any areas of bone with cancer cells.
Special notes
The dye leaves your body in urine after a few hours; you may be told to avoid children and pregnant women for a number of hours.
Before having scans, tell the doctor if you have any allergies or have had a reaction to dyes during previous scans. You should also let them know if you have diabetes or kidney disease or are pregnant or breastfeeding.
