Further tests after diagnosis

If you have been diagnosed with thyroid cancer, you will have further tests to check the size and position of the cancer. The tests will also show if the cancer has spread. The tests will help you and your doctor decide on the best treatment for you.

Tests you may have include:

  • MRI (magnetic resonance imaging) scan – this uses magnetism to build up a picture of your body.
  • CT (computerised tomography) scan – this uses x-rays to build up a three-dimensional picture of the inside of your body.
  • PET/CT (positron emission tomography) scan – this uses low-dose radiation to identify areas of cancer.
  • Vocal cord check – this is when a thin, flexible tube with a small camera at the end is passed through your nose to look at how your vocal cords move.

Waiting for your test results can be difficult. It can help to talk about your worries with someone close to you.

Further tests

If the tests show that you have thyroid cancer, your specialist may want to do some further tests. These are to find out the size and position of the cancer and whether it has spread to other parts of the body. This is called staging and will help you and your doctor decide on the best treatment for you. You may have these tests after surgery.

Tests may include the following.


MRI scan

An MRI scan uses magnetism to build up a detailed picture of areas of your body. The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it is safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips or bone pins, etc.

You should also tell your doctor if you have ever worked with metal or in the metal industry as very tiny fragments of metal can sometimes lodge in the body. If you do have any metal in your body, it is likely that you will not be able to have an MRI scan. In this situation, another type of scan can be used. Before the scan, you will be asked to remove any metal belongings including jewellery.

Some people are given an injection of dye into a vein in the arm, which does not usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test, you will lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It is painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It is also noisy, but you will be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.


CT (computerised tomography) scan

A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan takes 10 to 30 minutes and is painless. It uses a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with.

You may be asked not to eat or drink for at least four hours before the scan.

You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. It’s important to let your doctor know if you are allergic to iodine or have asthma, because you could have a more serious reaction to the injection.

If you are given a drink or injection, this may affect treatment with radioactive iodine. Your doctor or specialist nurse will be able to discuss this with you. You will probably be able to go home as soon as the scan is over.


PET-CT scan

This is a combination of a CT scan, which takes a series of x-rays to build up a three-dimensional picture, and a positron emission tomography (PET) scan. A PET scan uses low-dose radiation to measure the activity of cells in different parts of the body.

PET-CT scans give more detailed information about the part of the body being scanned. You may have to travel to a specialist centre to have one. You cannot eat for six hours before the scan, although you may be able to drink. A mildly radioactive substance is injected into a vein, usually in your arm. The radiation dose used is very small. You will wait for at least an hour before you have the scan. It usually takes 30 to 90 minutes. You should be able to go home after the scan.


Vocal cord check

Your doctor will check your vocal cords before and after surgery to remove your thyroid gland. This is because the nerves that control your vocal cords are close to the thyroid gland and they can be damaged during surgery.

The doctor may use a local anaesthetic spray to numb your nose and throat. Then they pass a thin, flexible tube with a small camera at the end (nasendoscope) through your nose to look at how your vocal cords move. This can be a little uncomfortable, but it should not be painful.

You may be asked to avoid eating or drinking for a few hours after the test, until the local anaesthetic wears off.

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