Diagnosis

Doctors use many tests to diagnose a tumor and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of tumors, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the tumor has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of tumor suspected
  
  
• Severity of symptoms
  
  
• Previous test results

Meningioma is often not diagnosed until symptoms appear. The neuro-oncologist (a doctor who specializes in diagnosing and treating brain tumors and other tumors of the nervous system) can use the patient’s symptoms as clues to the location of the tumor. In addition to obtaining the patient’s detailed medical history and doing a physical examination, an oncologist or neuro-oncologist may order some of the following tests to determine the presence, and perhaps the subtype or grade (how closely the tumor cells resemble normal tissue under a microscope), of meningioma:

Neurological, vision, and hearing tests. These tests help determine the suspected tumor’s effects on the brain’s functioning. An eye examination can detect changes to the optic nerve caused by a meningioma that is putting pressure on it.

Stereotactic neurosurgery or biopsy. In this procedure, doctors use computer guidance to insert a needle into a precise location and retrieve a tissue sample of the tumor. A biopsy is the only definitive way a meningioma diagnosis can be made. A biopsy can be performed by needle placement (meaning by stereotactic technique), or it can be done at the time of surgery when the tumor is exposed and available for direct inspection by the surgeon. Most meningiomas are removed rather than simply biopsied, and as a result, most surgery done for meningioma is not done as a stereotactic procedure, but rather by an open craniotomy (surgery where part of the skull is removed to provide access to the brain).

Imaging tests

Radiologic tests are most useful when they are combined with the patient’s medical history, physical examination, and neurological tests. This combination of results helps to more accurately determine where the tumor began, and whether or where it has spread. The most common imaging tests used for diagnosing meningioma include:

Computed tomography (CT or CAT) scan. A CT scan takes x-rays of the head from many different angles. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail. A CT scan is best for detecting changes in the skull bone sometimes caused by meningioma.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. MRIs may create more detailed pictures than CT scans and are the preferred method of diagnosing meningioma.

X-ray. An x-ray is a picture of the inside of the body. An x-ray of the head can sometimes help doctors determine the presence and location of meningioma, but is not sufficient to diagnose the type of tumor.

Cerebral angiogram. A cerebral angiogram is a type of x-ray, or series of x-rays, of the head that shows the arteries and veins in the brain. X-rays are taken after a contrast medium (a special dye) is injected into the main arteries of the head. Because a meningioma can block important veins that drain blood from the brain, it is sometimes important to get an angiogram to allow proper planning before an operation is performed.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images. A PET scan is rarely used in the evaluation of meningioma.

Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes a sample of cerebrospinal fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain types of cancer). CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure. Lumbar puncture is rarely needed in patients with meningioma.

Electroencephalography (EEG). An EEG is a noninvasive test in which electrodes are attached to a person’s scalp to measure electrical activity of the brain. Specifically, EEGs are used to detect seizure activity. Because meningiomas can cause seizures in some patients, EEGs are occasionally needed for patients with this tumor.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.