A variety of tests are used to detect and diagnose brain tumors. These tests can also show your doctor what type of brain tumor it is and if it has spread to other parts of the body. It is likely that your doctor will also run certain tests to determine the most effective course of treatment.
Brain Tumor Imaging Tests
The primary method for detecting and diagnosing a brain tumor is imaging. Imaging tests can also help doctors determine if the tumor is a primary brain tumor or if it is cancer that has spread to the brain from another location within the body. Imaging diagnostic tests typically include:
- Magnetic Resonance Imaging (MRI). The use of magnetic fields, not x-rays, to produce detailed images of the body.
- Computed Tomography (CT) scan. A test that creates a 3-D picture of the inside of the body using x-rays taken from different angles.
- Positron Emission Tomography (PET) or PET-CT scan. A test that creates pictures of organs and tissues using various substances, such as sugars or proteins. A PET scan is usually combined with a CT scan.
- Cerebral arteriogram. An X-ray (or series of X-rays) of the head that shows the arteries in the brain
Other diagnostic tests your doctor may perform to determine if a brain tumor is present can include:
- Lumbar puncture or spinal tap. A procedure in which a needle is used to take a sample of cerebrospinal fluid (CSF) to look for tumor cells, blood, or tumor markers
- Myelogram. A test used to find out if the tumor has spread to the spinal fluid, other parts of the brain, or the spinal cord
- Molecular testing of the tumor. Identifying specific genes, proteins, and other factors, such as tumor markers, unique to the tumor
- Neurological, vision, and hearing tests. Used see if a tumor is affecting brain functions
- Neurocognitive assessment. A detailed assessment of all major brain functions, including storage and retrieval of memory, language abilities, dexterity, calculation, and the patient's overall well-being
- Electroencephalography (EEG). A noninvasive test in which electrodes are attached to the outside of the patient’s head to measure electrical activity of the brain
- Evoked potentials. The use of electrodes to measure the electrical activity of nerves which could be affected by a growing tumor.
Your doctor will consider various factors, including the type of brain tumor suspected, signs and symptoms, your age, current medical condition, and previous test results before choosing a diagnostic test.
If imaging tests show there may be a brain tumor, the next step would be to perform a biopsy, which is the removal of a small amount of tissue for examination under a microscope. It is the only definitive way a brain tumor can be diagnosed.
As with most other cancers, brain tumors are not diagnosed until after the patient is experiencing symptoms.