Tests to diagnose brain tumours

You usually have tests to check for a brain or spinal cord tumour. If you have a brain tumour, these tests can also help your doctor decide what treatment you need. These tests include:

  • scans to look at your brain (MRI scan, CT scan, PET-CT scan)
  • a test to look at a sample of brain tumour cells (biopsy)
  • a test of your nervous system (neurological examination)

Brain tumours can be benign (non cancerous) or malignant (cancerous). The tests help the doctor find out what type of tumour you have.

Tests your GP might do

Most people start by seeing their GP. Your GP can do some tests to help them decide whether you need to see a specialist. Your GP might:

  • do a test of your central nervous system Open a glossary item (neurological examination)
  • examine other parts of your body to check for any other problems or abnormalities

Neurological examination

Depending on your symptoms your GP might test your nervous system (neurological examination). If at first you have a telephone appointment, they will give you an appointment to come to the GP surgery.

Your GP might:

  • look into your eyes to see if there are any changes
  • test your reflexes by tapping your knee with a rubber hammer
  • ask simple questions to test your memory
  • find out if you have any numbness, odd sensations or weakness
  • check your hearing
  • ask you to do heel to toe walking to check your balance 

They will refer you for an urgent scan of your brain if they think there’s any chance your symptoms could be due to a brain tumour.

Depending on the results of your tests, your GP might refer you to a specialist. You usually see a doctor who specialises in diagnosing and treating problems of the brain and spinal cord. This might be a neurologist or a neurosurgeon. It depends on what tests you have had, and what the tests show. 

Tests at the hospital

If your GP thinks there’s any chance your symptoms could be due to a brain tumour, you will have further tests at the hospital. These might include:

  • an MRI scan with contrast Open a glossary item
  • a CT scan with contrast
  • a PET CT scan
  • taking a sample of your brain tumour cells (biopsy)
  • an x-ray to show blood vessels in your brain (brain angiogram)
  • a test to check the fluid around the brain and spinal cord (lumbar puncture)

You usually have an injection of contrast just before your MRI or CT scan. Contrast is an injection of a dye (contrast medium) which you have through a small plastic tube (cannula) into a vein in your arm. 

The contrast makes certain tissues and blood vessels show up more clearly. This gives doctors more detailed information about your tumour, and how it's likely to behave.

MRI scan

MRI stands for magnetic resonance imaging. It uses magnetism and radio waves to take pictures of the inside of the body.

You might have some specialised MRI scans. These include:

  • contrast enhanced scans to provide more information about the tumour
  • magnetic resonance spectroscopy (MRS) which looks at the chemicals in the tumour
  • perfusion MRI scans that look at the blood flow in different parts of the brain
  • functional MRI scans (fMRI) that can pick up brain activity 

During a functional MRI scan, the radiographer will ask you to do certain things such as move your hand, tap your fingers or speak.  

CT scan

CT (or CAT) scan stands for computed (axial) tomography. It is a test that uses x-rays and a computer to create detailed pictures of the inside of your body.

You might have a CT scan of the brain to help diagnose a brain tumour if:

  • you need to have an emergency scan to find out what is causing your symptoms
  • you are unable to have an MRI scan (for example, because you have a pacemaker)
  • your doctors want to look at the bones close to your tumour

You might also have a CT scan of your tummy (abdomen) and chest to check whether you have cancer anywhere else in your body. This is to see whether the tumour in your brain might have spread there from cancer elsewhere in your body.

In adults, cancer that has spread to the brain from another part of the body (secondary brain cancer) is much more common than cancer that started in the brain (primary brain tumour). 

PET-CT scan

A PET-CT scan combines a CT scan and a PET scan. It gives detailed information about your tumour.

The CT scan takes a series of x-rays from all around your body and puts them together to create a 3 dimensional (3D) picture. The PET scan uses a mildly radioactive drug to show up areas of your body where cells are more active than normal. 

You might have a PET-CT scan of the brain to help diagnose your brain tumour. It can help your doctor:

  • diagnose your tumour and help them take a sample of cells (biopsy)
  • find out whether an abnormal area on your scan after treatment is your tumour continuing to grow, or is because of brain changes due to treatment

You may also have another type of PET scan called SPECT. This stands for single photon emission computed tomography. SPECT is similar to a normal PET scan but it can show how the blood flows in your brain.


A biopsy means taking a small tissue sample from your brain tumour and looking at it under a microscope. They send the samples to a laboratory. A specialist doctor looks at the samples under a microscope to diagnose what type of tumour you have.

A specialist doctor (neurosurgeon) takes the biopsy. You usually have it as part of the operation to remove the brain tumour, but you may also have it on its own. You usually have a biopsy of your brain under general anaesthetic. This means that you will be asleep and won’t feel anything.

There are different types of biopsies. The difference between them is the way the surgeon does the biopsy. You might have:

  • a biopsy as part of a larger operation to remove the tumour
  • a needle biopsy - the surgeon takes a small sample
  • an open biopsy - the surgeon takes a larger sample, or several smaller samples together
  • a neuroendoscopy


Neuroendoscopy is a way of taking samples of tissue from a brain tumour. Doctors take samples of tissue (biopsy) to look at under a microscope. This helps your doctor decide the best treatment for you.

You might have a neuroendoscopy to take samples of tissue from:

  • the fluid filled spaces of the brain (ventricles)
  • the pineal region - this is an area in the middle of the brain, just behind the brain stem

You usually have a neuroendoscopy under general anaesthetic. This means that you will be asleep and won’t feel anything. 

Brain angiogram

An angiogram is an x-ray that can show blood vessels. A specialist doctor called a neuroradiologist injects a dye (contrast medium). They then take x-ray images of your brain. They look at your brain on the x-ray screen to see:

  • which blood vessels supply the tumour
  • if the tumour is near any major blood vessel

This test is also called cerebral angiography. You might have a brain angiogram if:

  • your tumour is growing very deep inside your brain
  • you have a type of brain tumour called meningioma

Lumbar puncture

A lumbar puncture is a test to check the fluid that circulates around the brain and spinal cord. This is called the cerebrospinal fluid or CSF.

Certain types of brain tumours can spread from the brain to the CSF. So doctors might take some of the CSF to test for tumour cells. They use a needle to take a sample of the CSF from your lower back.

Sometimes, the pressure inside the brain and spinal canal (the intracranial pressure) is too high. It might not be safe to do a lumbar puncture if this happens. 

Blood tests

Blood tests can:

  • check your general health, including how well your liver and kidneys are working
  • check numbers of blood cells
  • help diagnose certain brain tumours such as pituitary gland, pineal region and germ cell tumours

Some brain tumours such as pituitary gland, pineal region and germ cell tumours can change the levels of certain hormones and chemicals in your body. You may have blood tests to check for specific hormones and markers to help diagnose a brain tumour. 


The tests you have helps your doctor find out if you have a brain tumour and how it might behave. This is the grade of the tumour.

This is important because doctors recommend your treatment according to the type and grade of the tumour.

Coping with a brain tumour

Coping with a diagnosis of a brain or spinal cord tumour can be difficult. There is help and support available to you and your family.

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Last reviewed: 
09 Jun 2023
Next review due: 
09 Jun 2026

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