Understanding Brain Cancer: The Diagnosis

The first step in diagnosing brain tumors is to do a neurologic exam. This means your doctor will check your vision, hearing, alertness, muscle strength, coordination and reflexes. Your doctor will also examine your eyes to check for swelling. If they are swollen, this can indicate a tumor pressing on the nerve that connects the eye and brain.

CT scan (CAT scan or computed tomography): The CT scan is an X-ray test that produces detailed pictures of your body. Instead of taking one picture, like a regular X-ray does, a CT scanner takes many pictures. It does this by rotating around you while you lie on a table. Then a computer combines all these images. That produces a 3-dimensional picture that can show a tumor.

Before any pictures are taken, you may have to drink 1 to 2 pints of a liquid. It is called oral contrast. This fluid helps outline your intestine. This helps the doctor identify tumors. You may also receive an IV (intravenous line) in your arm or hand. A different type of contrast dye can be injected through the IV. Its purpose is also to outline structures in your body.

The injection may make you feel flushed or warm. It is a little uncomfortable, but not painful. Many patients say that having to lie still is difficult.

MRI scan (magnetic resonance imaging): An MRI scan provides detailed pictures like CT scans. The difference is that MRI scans use radio waves and strong magnets instead of X-rays. The energy from the radio waves produces patterns. A computer takes these and turns them into detailed images of specific parts of your body.

MRI scans are often little more uncomfortable than CT scans. For one thing, an MRI takes up to an hour. You may be placed inside a narrow tube. This can feel confining. There are newer, open MRI machines in many hospitals and clinics around the country.

Angiogram: In this procedure, dye is injected into your bloodstream. This makes blood vessels in your brain show up on an X-ray. If you have a brain tumor, the X-ray can show the tumor or blood vessels that are leading into the tumor.

Spinal tap: In a spinal tap, your doctor removes a sample of cerebrospinal fluid. This is the fluid that fills the space in and around your brain and spinal cord. You will be given local anesthesia before this procedure. Here’s what you can expect. Your doctor will use a long, thin needle to take fluid from the lower part of your spinal column. The whole procedure takes about 30 minutes. You will have to lie flat for several hours after the spinal tap. This will keep you from getting a headache. Once the fluid is drawn, a laboratory checks the fluid for cancer cells.

Understanding Brain Biopsy

A biopsy is the procedure for removing tissue to check for tumor cells. A pathologist then examines the cells under a microscope to check for abnormal cells. A biopsy can change:

  • Cancer.
  • Tissue changes that can lead to cancer.
  • Other conditions.

A biopsy is the only way to diagnose a brain tumor. It’s also the way your doctor can tell how advanced the tumor is.

A biopsy can be done:

  • At the same time as treatment. The surgeon will take a sample of the tissue when you have surgery to remove all or part of the tumor.
  • Through stereotactic biopsy. You will have either local or general anesthesia and wear a rigid head frame during this procedure. The surgeon will make a small incision in the scalp and drill a small hole into your skull. This is called a burr hole. The surgeon will use a CT or MRI to help guide the needle through the burr hole. Then a sample of tissue is drawn out with the needle.

A needle biopsy may be used if the tumor is:

  • Deep inside the brain.
  • In a part of the brain that can’t be operated on.

If the tumor is in your brain stem or certain other areas, your surgeon may not be able to do a biopsy. Surgery in these areas could harm normal brain tissue. If the tumor is in such a delicate area, the doctor will rely on MRI, CT scans, or other imaging tests.

If your doctor recommends a biopsy, you may want to ask the following questions:

  • Why do I need a biopsy? How will the biopsy results affect my treatment plan?
  • What kind of biopsy will I have?
  • How long will it take? Will I be awake? Will it hurt?
  • What are the chances of infection or bleeding after the biopsy? Are there any other risks?
  • How soon will I know the results?
  • If I do have a brain tumor, who will talk with me about treatment? When?

Next: How is brain cancer staged? 

Back to “Understanding Brain Cancer: An Introduction”