Diagnosing Brain Tumors

By coming to Stanford Health Care for your diagnosis, you can be confident that all of the right tests will be done quickly and with great expertise from years of experience and advanced training. Our brain tumor diagnosticians work around the clock to ensure that your treatment begins with the correct and accurate diagnosis, and that you understand it clearly.

Diagnosis of a brain tumor is based mostly on the types of cells involved and the tumor location. Successful treatment begins with the skills of the diagnostic team.

How is a brain tumor diagnosis made?

Brain and spinal cord tumors in adults are usually found because of symptoms that patients report to their primary care doctor. These symptoms can range from headaches to vision or balance problems, from speech problems to nausea. Symptoms may begin gradually and become worse over time, or they can happen suddenly, as with a seizure.

When a brain tumor is suspected, many different tests are used to confirm the diagnosis. Your community-based physician may order some of the tests themselves and based on the results, refer you to the Stanford Brain Tumor Center. Because many brain tumor symptoms are common to other medical conditions, it is essential that they be diagnosed by an expert. 

What you need to know

Diagnostic tools used for brain tumor diagnosis and evaluation

The following tests and procedures are used to diagnose a brain or spinal tumor. After treatment for a tumor, some of the tests and procedures are repeated to find out how much tumor is left and how further treatment should proceed.

  • Physical exam and personal history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
  • Neurological exam: A series of questions and tests to check the brain, spinal cord, and nerve function. The exam checks a person’s mental status, coordination, and ability to walk normally and how well the muscles, senses, and reflexes work.
  • Visual field exam: An exam to check your field of vision (the total area in which you can see objects around you). This test measures both central vision (how much a person can see when looking straight ahead) and peripheral vision (how much a person can see in all other directions while staring straight ahead). Any loss of vision may be a sign of a tumor that has damaged or pressed on the parts of the brain that affect eyesight.
  • Gene testing: A laboratory test in which a sample of blood or tissue is tested for changes in a genetic material that has been linked with a certain type of brain tumor. Much of this important research is being done at our own Stanford University Medical Center. This test may also be done to diagnose one of the few inherited medical conditions that are associated with brain tumors.
  • CT scan (CAT scan): A neuroimaging procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an X-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography.
  • MRI (magnetic resonance imaging): A neuroimaging procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of the brain and spinal cord. A substance called gadolinium is injected into a vein to help the physicians see the image more clearly. The gadolinium collects around cancer cells so they show up brighter in the picture. Sometimes a procedure called magnetic resonance spectroscopy (MRS) is done during the MRI scan. An MRS is used to diagnose tumors based on their chemical make-up.
  • fMRI (functional MRI): During an fMRI, the patient is asked to perform certain activities to help the neurosurgeons map the functional areas of the brain before surgery takes place.
  • PET scan (positron emission tomography scan): A PET scan is a neuroimaging technique used to find malignant tumor cells. A small amount of radioactive glucose (a sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the brain. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
  • A lumbar puncture (also called a spinal tap) can be used to analyze the fluid in the spinal cord. This test is helpful for spinal tumor assessment and also for measuring whether certain cancers have spread to the brain.

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