Further tests for diagnosing brain tumours

Brain MRI (magnetic resonance imaging) scan Back to top

This test uses magnetic fields to build up a detailed picture of the inside of your head. Before the scan you may be asked to complete and sign a checklist. This is to make sure that it’s safe for you to have an MRI scan, because the scanner is a powerful magnet. The checklist asks about any metal implants you may have, for example a pacemaker, surgical clips, 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’s likely that you won’t be able to have an MRI scan. In this situation another type of scan can be used.

Before having the scan, you’ll be asked to remove any metal belongings including jewellery. You are usually given an injection of dye into a vein in the arm, which doesn’t 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’ll be asked to lie very still on a couch inside a long cylinder (tube) that is open at both ends. The whole test can take up to an hour. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones. You will be able to hear, and speak to, the person operating the scanner.

Brain CT (computerised tomography) scan Back to top

This is a series of x-rays, which builds up a three-dimensional picture of the inside of your head. During the test you will be asked to lie with your head inside an opening in the scanner. The scan is painless but takes longer than a normal x-ray (from 5 to 10 minutes). It may be used to identify the exact area and size of the tumour.

Most people who have a CT scan are given an injection of a liquid into a vein, to allow particular areas of the brain to be seen more clearly. The injection may make you feel hot all over for a few minutes. Before having the injection, it is important to tell your doctor and the person doing the scan if you are allergic to iodine or have asthma or diabetes. You'll probably be able to go home as soon as the scan is over.

 

Biopsy Back to top

It's often necessary for the doctor to take a small part of the tumour (a biopsy) to find out exactly what type of tumour you have (see Surgery| for more information).

Skull x-ray Back to top

Very rarely, brain tumours may show up on an x-ray picture. The test is simple and painless. You will have to lie on a couch in the hospital’s x-ray department and you will be asked to keep your head still for a few seconds.

PET (positron emission tomography) scan Back to top

A PET scan uses low-dose radioactive glucose (a type of sugar) to measure the activity of cells in different parts of the body. A very small amount of the mildly radioactive substance is injected into a vein, usually in your arm. Tumours normally absorb more of the glucose and the radioactivity shows up on the scan.

After the injection you may be asked to lie in a dark room with your eyes closed. You'll then be taken to the scanning room and asked to lie on a couch with the scanning ring around you. The dose of radiation you receive is no more than a normal x-ray.

A PET scan is not routinely used to diagnose a brain tumour but it may help to tell whether a tumour is growing and whether it is cancerous (malignant) or benign. PET scans aren’t available in all hospitals, and you may have to travel to a hospital some distance away from your home to have one.

SPECT (single photon emission computerised tomography) scan Back to top

This test is similar to a PET scan. It can help to detect abnormalities in the blood brain barrier as it looks at blood flow through the brain.

You are given an injection of a very mild radioactive substance, usually in your arm. This susbstance travels in the blood to the brain. Then, in the scanning room, pictures (scans) of the brain are taken.

Blood tests and chest x-rays Back to top

There isn't a specific blood test that can detect brain tumours, but you may have blood tests to check your general health. A chest x-ray may also be done as part of a general health check.