Further tests for brain tumours

These tests help the doctor to find out exactly what type of brain tumour you have. They also help the doctors to find out how big the tumour is. This information is important for the doctors to know which is the best treatment.

MRI is a scan using magnetism. MRI usually gives the clearest scan of the brain and spine and will almost certainly show up a brain tumour. You will usually have an injection of a dye, called contrast medium, to make the MRI scan clearer. Specialised MRI scans called Magnetic Resonance Angiography scans or MRA can show the blood vessels. Magnetic Resonance Spectroscopy or MRS look at chemicals in the tumour. You may need to have more than one MRI as your specialist gathers information about your condition. There is more about having an MRI in the section about cancer tests.

Taking a sample of tissue is the only sure way to diagnose many brain tumours. Looking at the cells under a microscope is the only guaranteed way to identify the type of brain tumour and grade of the tumour. For some brain tumours, you will have a biopsy as the first part of an operation to remove all or part of your tumour. For others, you may just have a biopsy and then go onto have other treatment such as radiotherapy. In some cases it is not possible to have a biopsy as the tumour is in an area of the brain that is too difficult to operate on. This may be because the tumour is close to major blood vessels or is in an area of the brain that controls vital functions in the body. 

There is detailed information about having a biopsy in the section about surgery for brain tumours.

A lumbar puncture is only used for certain types of brain tumour that can spread within the central nervous system. The test involves getting a sample of cerebrospinal fluid and examining it for cancer cells. Doctors can't always do this test on people with brain tumours. Sometimes, the pressure inside the brain and spinal canal (the intracranial pressure) is too high and to do a lumbar puncture would be dangerous. There is detailed information on having a lumbar puncture in the section about cancer tests.

Children usually have a sedative or a short general anaesthetic to have this test. There are two main reasons for this. It is very important to keep very still and they may find the test upsetting.

Your doctor may ask you to have a scan of your tummy (abdomen) and a chest X-ray. The scan and X-ray are to check whether you have cancer anywhere else in your body. In adults, cancer that has spread to the brain (secondary brain tumour) is much more common than cancer that started in the brain (primary brain tumour). So it is sensible for your doctor to check. Ultrasound uses sound waves to build up a picture of the area being scanned. It is completely painless and only takes a few minutes. There is more about having an ultrasound in the section on cancer tests.

An angiogram examines the blood supply to the area being scanned. Angiograms are not done very often for brain tumours these days. But they are an important test for meningiomas and some other types of brain tumour. They give surgeons the following information.

• Which blood vessels are supplying the tumour
• If the tumour is attached to any major blood vessels in the brain

Angiograms are sometimes used when a tumour is growing very deep inside the brain.

For this test you usually have to go into hospital overnight. You will need a sedative or a general anaesthetic. You have the angiogram in the X-ray department. First, you have a tube (catheter) put into a blood vessel in your groin. The doctor injects a dye that shows up on X-ray into the tube. After a minute or so, the dye will have circulated through your bloodstream into the blood vessels into your brain. Your surgeon will look at your brain on an X-ray screen to see exactly how near the tumour is to the blood vessels.

Depending on the type of brain tumour you have, your surgeon may then inject something to block the blood vessels that carry blood to the tumour. This will help to shrink the tumour before you have surgery to remove it. This procedure is called embolisation or interventional angiography. There is a small risk of a stroke from this procedure. But the risk is usually small compared to the benefit of treating the tumour. Before you have this treatment, your specialist will explain all this to you and you will be able to ask questions or talk through any worries that you have.

PET scans are a fairly new type of scan. They are not available at all hospitals. So if your specialist wants you to have one, you may have to travel to another hospital. PET scans can show up the rate of activity of body tissues. The scan traces a small amount of radioactive glucose that you have as an injection. The brain uses up the glucose and the scan measures how quickly this happens. The speed of glucose use by the area of the brain being scanned helps to show if a brain tumour is benign or malignant. There is information about having a PET scan in the section about cancer tests.

SPECT stands for Single Photon Emission Computed Tomography. It is similar to a PET scan, but uses much simpler equipment to get information about chemicals in the brain tumour. As with a PET scan, you have an injection of a very small amount of a radioactive chemical. This does not harm you. The radioactive chemical circulates in your blood to your brain and shows up the brain tumour on the scanner.

A myelogram gives pictures of the spinal cord. First you have a lumbar puncture. Then the doctor injects a dye into the area around the spinal cord. This is the space that the cerebrospinal fluid flows through. The dye spreads through this fluid. Then you have X-rays taken. If a tumour is blocking the flow of the fluid, the dye cannot get past it. And so the position of the tumour will show up on the X-rays.

This test is done under general anaesthetic. A 2cm hole is drilled into the skull. A fine tube called a neuroendoscope is put into the hole and into the fluid filled chambers of the brain (the ventricles). This test may be done to

• Take a biopsy of a tumour that is in or near the ventricles
• Take fluid samples for tests
• Drain fluid if too much has built up and caused an increase in pressure (hydrocephalus)

You will be asked to go back to the hospital when your test results have come through. This is bound to take a little time, even if only a few days. You are likely to feel anxious during this time. While you are waiting for results it may help to talk to a close friend or relative about how you feel. Or you may want to contact a cancer support group to talk to someone who has been through a similar experience. If you want to find people to share experiences with online, you could use Cancer Chat, our online forum. Look in our general cancer organisations section for  information about people who can offer support. Our counselling section has details of counselling organisations who can help you to find a counsellor in your area.