BRAIN TUMOR

Screening And Diagnosis

The diagnosis of brain tumors has been increasing in recent years. But experts aren't sure whether that's due to better detection methods or an actual increase in the number of tumors.

Diagnosing a brain tumor usually involves several steps. Your physician may perform a neurological exam, which includes checking your vision, hearing, balance, coordination and reflexes, among other things. Depending on the results of that exam, your doctor may request one or more of these tests:

• Computerized tomography (CT) scan. A CT scan uses a sophisticated X-ray machine linked to a computer to produce detailed, two-dimensional images of the brain. You lie still on a movable table that's guided into what looks like an enormous doughnut where the images are taken. A special dye may be injected into the bloodstream after a few CT scans are taken. The dye helps make tumors more visible on X-ray. A CT scan is painless and generally takes less than 10 minutes.

• Magnetic resonance imaging (MRI) scan. This scan uses magnetic fields and radio waves to generate images of the brain. You lie inside a cylindrical machine for 15 minutes to an hour. MRI scans are particularly useful in diagnosing brain tumors because they outline soft tissues of the body as well as bone. Sometimes a special dye is injected into the bloodstream during the procedure. The dye sometimes makes tumors more visible from healthy tissue.

• Angiogram. This test involves injecting a special dye into the bloodstream. The dye, which flows through the blood vessels in the brain, can be seen on X-ray. This test helps show the location of blood vessels in and around a brain tumor.

• X-rays of the head and skull. An X-ray of the head may show alterations in skull bones that could indicate a tumor. It may show calcium deposits, which are sometimes associated with brain tumors. However, an X-ray is a far less sensitive test than brain scans and so is used less often.

• Other brain scans. Other tests, such as magnetic resonance spectroscopy (MRS), single-photon emission computed tomography (SPECT) or positron emission tomography (PET) scanning, help doctors gauge brain activity by studying brain metabolism and chemistry and blood flow within the brain. These scans can be combined with MRIs to help doctors understand the effects of a tumor on brain activity and function.

If a brain tumor is seen on a brain scan, especially if multiple tumors are seen, doctors may test for cancer elsewhere in the body.

In addition to brain scans and other tests, surgery is usually required to diagnose a brain tumor and confirm its type. Surgery allows the brain surgeon to obtain a biopsy. A biopsy involves removing a piece of the tumor, so it can be viewed under a microscope.

A biopsy can be performed as part of surgery to remove a brain tumor. A biopsy can also be performed as part of a separate diagnostic procedure.

A needle biopsy may be used for brain tumors in hard to reach areas within the brain. The surgeon drills a small hole, called a burr hole, into the skull. A narrow, thin needle is then inserted through the hole. Tumor tissue is removed using the needle.