How Are Brain Tumors Diagnosed?
To find the cause of a person’s symptoms, the doctor asks about the patient’s personal and family medical history and does a complete physical examination. In addition to checking general signs of health, the doctor does a neurological exam. This includes checks for alertness, muscle strength, coordination, reflexes, and response to pain. The doctor also examines the eyes to check for swelling caused by a tumor pressing on the nerve that connects the eye and the brain.
Depending on the results of the physical and neurological examinations, the doctor may request one or both of the following:
A CT (or CAT) scan is a series of detailed pictures of the brain. The pictures are created by a computer linked to an x-ray machine. In some cases, a special dye is injected into a vein before the scan. The dye helps to show differences in the tissues of the brain.
MRI (magnetic resonance imaging) gives pictures of the brain, using a powerful magnet linked to a computer. MRI is especially useful in diagnosing brain tumors because it can “see” through the bones of the skull to the tissue underneath. A special dye may be used to enhance the likelihood of detecting a brain tumor.
The doctor also may request other tests:
A skull x-ray can show changes in the bones of the skull caused by a tumor. It can also show calcium deposits, which are present in some types of brain tumors.
In a brain scan, areas of abnormal growth in the brain are revealed and recorded on special film. A small amount of a radioactive material is injected into a vein. This dye is absorbed by the tumor, and the growth shows up on the film (the radiation leaves the body within 6 hours and is not dangerous).
An angiogram, or arteriogram, is a series of x-rays taken after a special dye is injected into an artery (usually in the area where the abdomen joins the top of the leg). The dye, which flows through the blood vessels of the brain, can be seen on the x-rays. These x-rays can show the tumor and the blood vessels that lead to it.