Diagnostic tests for brain tumours
If your doctor suspects you may have a brain or spinal cord tumour, they will take your medical history and ask about your symptoms. After that, you will have a physical examination. You may then be referred to have one or more scans/tests to confirm a diagnosis of a brain or spinal cord tumour.
Children have the same type of diagnostic tests as adults, however young children may require a general anaesthetic for some of the tests.
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Your doctor will assess your nervous system to check how different parts of your brain and body are working, including your speech, hearing, vision and movement.
This is called a neurological examination and may include:
- checking your reflexes (e.g. knee jerks)
- testing the strength in your limb muscles
- walking, to show your balance and coordination
- testing sensations (e.g. your ability to feel light touch or pinpricks)
- brain exercises, such as simple arithmetic or memory tests.
The doctor may also test eye and pupil movements, and may look into your eyes using an instrument called an ophthalmoscope. This allows the doctor to see your optic nerve, which sends visual information from the eyes to the brain. Swelling of the optic nerve can be an early sign of raised pressure inside the skull.
You are likely to have blood tests to check your overall health. Blood tests can also be used to check whether the tumour is producing unusual levels of hormones, which could mean the pituitary gland is affected.
An MRI (magnetic resonance imaging) scan uses a powerful magnet and a computer to make cross-sectional pictures of your body. Let your doctor or nurse know if you have a pacemaker or any other metallic object in your body. The magnet can interfere with some pacemakers, but newer pacemakers are MRI-compatible.
For an MRI, you may be injected with a dye (contrast) that highlights any abnormalities in your brain. You will then lie on an examination table inside a large metal tube that is open at both ends.
The test is painless, but the machine can be noisy; some people feel anxious or claustrophobic in the tube. If you think you may become distressed, mention it beforehand to your medical team. You may be given medicine to help you relax or you might be able to bring someone into the room with you for support. You will usually be offered headphones or earplugs and a distress button to press if you are worried at any time. An MRI takes 30–45 minutes and you will be able to go home afterwards.
The pictures from an MRI scan are generally more detailed than pictures from a CT scan.
|Before having scans, tell the doctor if you have any allergies or have had a reaction to contrast during previous scans. You should also let them know if you have diabetes or kidney disease, or are pregnant.|
A CT (computerised tomography) scan uses x-rays to take many pictures of the inside of the body and then compiles them into detailed, cross-sectional pictures. Contrast may be injected into a vein to help make the scan pictures clearer. It may make you feel hot all over and leave a bitter taste in your mouth. You may also feel the need to pass urine. These side effects usually ease within minutes.
The CT scanner is a large, doughnut-shaped machine. You will lie on a table that moves in and out of the scanner. It may take about 30 minutes to prepare for the scan, but the actual test takes only about 10 minutes and is painless. You will be able to go home when the scan is complete.
You may have some of the tests listed below to estimate how quickly the tumour is growing (the grade) and whether it has spread into nearby tissue. This information helps your doctor plan treatment.
An MRS (magnetic resonance spectroscopy) scan is a specialised type of MRI. It can be done at the same time as a standard MRI. It looks for changes in the chemicals in the brain.
An MR (magnetic resonance) tractography scan helps show the message pathways (tracts) within the brain, e.g. the visual tracts. It can help plan treatment for gliomas.
MR perfusion scan
This type of scan shows the amount of blood flowing to various parts of the brain. It can also be used to help identify the type of tumour.
SPET or SPECT scan
A SPET or SPECT (single photon emission computerised tomography) scan shows blood flow in the brain. You will be injected with a small amount of radioactive fluid and then your brain will be scanned with a special camera. Areas with higher blood flow, such as a tumour, will show up brighter on the scan.
For a PET (positron emission tomography) scan, you will be injected with a small amount of radioactive solution. Cancer cells absorb the solution at a faster rate than normal cells and show up brighter on the scan.
Also called a spinal tap, a lumbar puncture uses a needle to collect a sample of cerebrospinal fluid from the spinal column. The fluid is checked for cancer cells in a laboratory.
If scans show an abnormality that looks like a tumour, some or all of the tissue may be removed for examination under a microscope. This is called a biopsy. In some cases, the neurosurgeon makes a small opening in the skull and inserts a needle to take a sample. In other cases, the biopsy is done during surgery to remove the brain tumour (craniotomy).
Every kind of cancer, including a brain tumour, changes the genes of the affected cells. These gene faults are not the same thing as genes passed through families. The fault is only in the structure of the tumour cells, not in the normal cells. The study of these gene changes is called cytogenetics or molecular genetics. A pathologist may run special tests on tumour cells to look for these gene changes. The results can help your doctors tailor the treatment to that tumour.
A/Prof Andrew Davidson, Neurosurgeon, Macquarie University Hospital, NSW; Dr Lucy Gately, Medical Oncologist, Oncology Clinics Victoria, and Walter and Eliza Hall Institute of Medical Research, VIC; Melissa Harrison, Allied Health Manager and Senior Neurological Physiotherapist, Advance Rehab Centre, NSW; Scott Jones, Consumer; Anne King, Neurology Cancer Nurse Coordinator, Health Department, WA; Dr Toni Lindsay, Senior Clinical Psychologist and Allied Health Manager, Chris O’Brien Lifehouse, NSW; Elissa McVey, Consumer; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Dr Claire Phillips, Deputy Director, Radiation Oncology, Peter MacCallum Cancer Centre, VIC.
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