In most cases, you will have a CT scan of the brain. This test is like an X-ray, but shows more detail in three dimensions. Usually, a harmless dye is injected into your bloodstream to highlight abnormalities on the scan.
No one knows what causes brain tumors; there are only a few known risk factors that have been established by research. Children who receive radiation to the head have a higher risk of developing a brain tumor as adults, as do people who have certain rare genetic conditions such as neurofibromatosis or Li-Fraumeni syndrome. But those cases represent a fraction of the approximately 35,000 new primary brain tumors diagnosed each year. Age is also a risk factor -- people over the age of 65 are diagnosed...
More often, the MRI scan is being used instead of a CT scan for suspected brain tumors. This is because MRI has a higher sensitivity for detecting the presence of, or changes within, a tumor. Currently, however, most institutions still use the CT scan as the first diagnostic test.
Skull X-rays are no longer widely used to diagnose brain cancer.
If your mental status has been the major change, blood or urine tests may be done to detect drug use.
If your scans indicate the presence of a brain tumor, you will be referred to a cancer specialist, called an oncologist. If one is available in your area, you should be referred to a specialist in brain tumors, called a neuro-oncologist.
The next step in diagnosis is confirmation that you have a cancer, usually by taking and testing a sample of the tumor. This is called a biopsy:
The most widely used technique for obtaining a biopsy is surgery. The skull is opened, usually with the intention of removing the whole tumor, if possible. A biopsy is then taken from the tumor.
If the surgeon is unable to remove the entire tumor, a small piece of the tumor is removed.
In some cases, it is possible to collect a biopsy without opening the skull. The exact location of the tumor in the brain is determined by using a CT or MRI scan while the head is held still in a frame. A small hole is then made in the skull and a needle guided through the hole to the tumor. The needle collects the biopsy and is removed. This technique is called stereotaxis, or stereotactic biopsy.
The biopsy is examined under a microscope by a pathologist (a doctor who specializes in diagnosing diseases by looking at cells and tissues).
Author: Charles Davis, MD, PhD, Research Director, Professor of Emergency Medicine, Department of Surgery, Division of Emergency Medicine, University of Texas Health Science Center at San Antonio. Brain Cancer Diagnosis from eMedicineHealth. Coauthor(s): Nitin Tandon, MD, Staff Physician, Department of Surgery, Division of Neurosurgery, University of Texas Health Science Center at San Antonio.
Editors: Brian F Chinnock, MD, Assistant Professor, Department of Emergency Medicine, Texas Tech University Health Sciences Center at El Paso; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jerry Balentine, DO, Professor of Emergency Medicine, New York College of Osteopathic Medicine; Medical Director, Saint Barnabas Hospital.