Metastatic Brain Tumors

Diagnosis

Diagnosing a brain tumor usually begins with a neurological exam by the neurologist, which includes checking vision, hearing, balance, coordination and reflexes. Depending on those results, the physician may request one or more tests described below. Results generally are available within 24 hours of testing in Mayo's state-of-the-art electronic medical record. A biopsy is usually required to diagnose a brain tumor and confirm its type.

Magnetic Resonance Imaging (MRI) Scan

This scan uses magnetic fields to generate images of the brain. The patient lies inside a cylindrical machine for approximately an hour. MRI scans are particularly useful in diagnosing brain tumors because they outline the normal brain structures in great detail. Sometimes a special dye is injected into the bloodstream to make tumors more distinguishable from healthy tissue (MRI angiography).

Computed 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. The patient lies 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.

Angiogram

A special dye is injected into the arteries that go to the brain. The dye, which flows through the blood vessels in the brain, can be seen on X-ray. This test helps locate blood vessels in and around a brain tumor. MR angiography can often be done in place of an angiogram.

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 and blood flow. These scans can be combined with MRIs to help physicians understand the effects of a tumor on brain activity and function. If a brain tumor is seen on a brain scan, especially multiple tumors, physicians may test for cancer elsewhere in the body.

X-rays of the Head and Skull

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

Biopsy

A biopsy is usually required to diagnose a brain tumor and confirm its type. In a biopsy, a piece of tumor is removed for examination under a microscope. A biopsy can be perfomed separately or as part of the surgery to remove the tumor.

A neuropathologist examines the tissue to determine the kind of tumor. This analysis should be performed by a pathologist who specializes in brain tumors. Correctly identifying the type of tumor is crucial to receiving the proper treatment. Studies have shown that the diagnosis may change substantially for at least one-third of patients when pathological review is performed by an experienced neuropathologist. Mayo's neuropathologists are internationally known for their expertise in diagnosing brain tumors.

Read more about brain tumor biopsies on the brain tumor pages.