Imaging tests allow the cancer care team to check for cancer and other problems inside the body.
- Imaging tests involve sending different types of energy, such as X-rays, sound waves, magnetic fields or radioactive particles, through the body.
- Energy patterns are changed by the different tissues and structures in the body and these are displayed as an image on a screen. They allow the cancer care team to see changes that may be caused by cancer.
There are four main types of imaging used to diagnose and assess Head and Neck Cancers:
- Computed Tomography (CT) Scan
- Magnetic Resonance Imaging (MRI) scan
- Positron emission tomography (PET) scans
- Ultrasound (US) scans
Computed Tomography (CT) Scan
Before a CT scan, you might be given a needle (injection) of a dye that will make any tumours easier to see. You might feel a bit hot or flushed for a few minutes after you have a dye injection. For some people (particularly those with kidney problems), the dye can be dangerous. Your doctor will speak with you about your general health and decide if a dye injection is right for you.
During the CT scan, you will lie on a table while it moves through the CT machine. This will take a few minutes.
The CT machine sends pictures to a computer screen. Your doctor can look at the computer screen to check for any signs of cancer. If you do have a tumour, a CT scan can help measure how big it is and show if it is affecting other parts of your body.
The amount of radiation you receive is small, and the risk of harm from it is low. However, you should not have a CT scan if you are pregnant.
Before you have a CT scan, speak with your doctor about the benefits and risks and any other questions you may have.
CT scans are painless (other than a needle for the dye) and you can go home once the scan is done.
Magnetic Resonance Imaging (MRI) Scan
Before an MRI scan, you might be given a needle (injection) of a dye that will help make any tumours easier to see.
The MRI machine is a powerful magnet, so you will need to remove any metal, such as jewellery. Your doctor and the staff will ask if you have any metal in your body, such as a pacemaker or rods, plates or screws holding bones in place. They will talk with you about whether it is safe to have an MRI scan.
During the scan, you will lie still on a table that moves into the MRI machine. The machine looks like a donut that moves over your body. The scan may take about 30 minutes or longer.
The MRI machine sends pictures to a computer screen. Your doctor can look at the pictures on the computer screen to check for any signs of cancer.
MRI scans are painless and have no radiation, however, they can be noisy. You may be given earplugs to help reduce the noise. Some people feel a bit uncomfortable or panicked lying in the MRI machine. You can take music to be played while you are in the MRI machine to help you feel less nervous. Remember, you can always speak to the person running the machine if you have any worries. But it is important to lie very still during the scan or the images will be blurry. If you panic when in small spaces, speak with your doctor before you go for the MRI about ways to make the scan more comfortable.
Positron Emission Tomography (PET) Scan
Before a PET scan, you will be given a needle (injection) containing a radioactive sugar (tracer). You will then need to wait between 30 and 90 minutes to let the mixture move around your body.
The radioactive sugar goes to parts of the body that have lots of cells growing, to help show where the cancer is. Because cancer cells absorb more radioactive sugar mixture than healthy cells, cancer cells show up brighter on the PET scan.
Before you have a PET scan, speak with your doctor about the benefits and risks and any other questions you have.
During the PET scan, you will lie on a table while it moves through the PET machine. It is important to lie still during the scan and not to talk, otherwise normal muscles will show up on the scan. The machine will send pictures to a computer screen. Your doctor can look at the pictures on the computer screen to check for any signs of cancer or if the cancer has spread. It is important to know that other illnesses than cancer, such as infection, can also show up on a PET scan.
A PET scan is painless and usually take about two hours.
During the test, gel will be spread on the skin and a small device called a probe will be moved over the area. The probe makes soundwaves that can be turned into a picture on a computer. Your doctor will look at the pictures for any signs of a lump that might need a biopsy.
Ultrasounds are painless and you can go home once the test is done. You don't need to do anything to get ready for a head and neck ultrasound. You can eat and drink as you would normally.