Brain Tumors

Diagnosis

Brain tumor diagnosis usually begins with a visit to the neurologist. The neurologist reviews your history, does a thorough neurological exam, reviews imaging tests and orders any additional testing. In Mayo's efficient system, exams are interpreted promptly, and results are available in Mayo's electronic records within hours.

Imaging tests

Mayo has an international reputation for high-quality imaging and rapid results. Radiologists who specialize in imaging the brain and nervous system ensure that each examination is performed and interpreted to the highest standard of quality.

Imaging tests may include:

• Magnetic resonance imaging (MRI) scan. MRI is a technique that uses a magnetic field and radio waves to create detailed images of the brain. Sometimes a special dye is injected into the bloodstream to make tumors appear different from healthy tissue (MR angiography). Functional MRI scans may be done to identify critical brain areas involved in speech and motor activity.
• 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. A CT scan can be very helpful in certain types of tumors, especially ones close to or involving bone.
• 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 tumor activity and blood flow.
• Angiogram. A special dye is injected into the arteries that feed the brain, making the blood vessels visible on X-ray. This test helps locate blood vessels in and around a brain tumor.

Biopsy

A biopsy involves removing a piece of the tumor for viewing under a microscope. The doctor needs to know the tumor type and grade to plan proper treatment.

At Mayo Clinic, a doctor who specializes in examining brain and nervous system tumors (neuropathologist) examines the tissue. This is critical for an accurate diagnosis. Mayo's neuropathologists are internationally known for their expertise in diagnosing brain tumors.

Tumor grading relates to how tumor cells look under the microscope. Grades 1 and 2 are low grade, Grade 3 is moderate, and Grade 4 is high. Low grade means that the tumor cells resemble normal brain cells. They usually grow slowly and are not likely to spread. In high-grade tumors, the cells look very abnormal and are more likely to grow quickly and spread.

Read more about brain tumor tests and diagnosis at MayoClinic.com.