Diagnosing Glioma & Astrocytoma

Astrocytoma is the most common form of glioma. These tumors may be diagnosed in children and adults.

Symptoms of an astrocytoma and other types of glioma occur when the tumor injures a part of the brain or spinal cord or increases pressure inside the skull. They vary depending on the tumor’s location in the brain and may include headache, weakness on one side of the body, seizures, vision changes, memory loss, or problems with balance and walking. Sometimes these tumors may cause drowsiness, fatigue, or personality and mood changes. In infants, the growing pressure of an astrocytoma tumor inside the skull may cause the head to enlarge.

The exact cause of gliomas is not known, but people with genetic cancer disorders, such as neurofibromatosis type 1—which causes nervous system tumors—may have an increased risk. Occupational exposure to radiation, oil refining, or rubber manufacturing may also increase a person’s chances of developing a glioma.

To diagnose a glioma or astrocytoma, Perlmutter Cancer Center doctors first perform a physical exam and obtain a medical history. Doctors also conduct a neurological examination, in which they evaluate a person’s mental status, reflexes, senses, and motor function. There are several other tests doctors may use to diagnose a glioma.

A doctor may order an MRI scan, in which a magnetic field, radio waves, and a computer create two- or three-dimensional images of the brain. You may receive an injection of a contrast agent to enhance the MRI image.

At Perlmutter Cancer Center, advanced MRI techniques are used to better understand the nature of a suspected glioma, including its grade and any DNA mutations. This information may help our doctors better predict the behavior of a particular tumor and may guide your treatment plan.

A CT scan uses X-rays to create cross-sectional, three-dimensional images of the brain. These scans are not typically used to help diagnose gliomas, but they can be useful if a person cannot have an MRI scan—for example, if a person has an implanted pacemaker.

Functional MRI, or fMRI, uses MRI imaging to measure the tiny metabolic changes that occur in an active part of the brain. Active areas represent important functional areas of the brain, such as the speech cortex or motor cortex.

During a functional MRI, a doctor asks you to speak or move in a certain way to identify the motor and speech areas of the brain, which can help with surgical planning.

In a perfusion MRI, a doctor can view the amount of blood flowing through different parts of the brain, as well as through a tumor. A faster growing tumor may require more blood flow for nourishment.

During the test, a contrast agent is injected into a vein to enhance the MRI images. This gives the doctor a real-time view of blood flow in the brain and a tumor so a doctor can identify the area to target during a biopsy. A perfusion MRI can also be used after treatment to help a doctor distinguish between a tumor and scar tissue and to help assess a tumor’s response to treatment.

A PET scan detects tumor growth using a small amount of radioactive glucose, or sugar, which is injected into a vein. This material collects in cancer tissue and is detected with a special camera, allowing doctors to determine whether cancer is present. A PET scan can help a doctor determine whether a tumor is low- or high-grade, which is useful for treatment planning.

After treatment, a PET scan may reveal if a tumor still contains cancer or if only scar tissue remains.

Perlmutter Cancer Center is one of the few centers in the country with a combined MRI/PET scanner. This equipment combines the advantages of both technologies in a single scan to better understand the behavior and nature of a tumor.

A stereotactic biopsy is a surgical procedure in which a doctor removes a small amount of brain tissue using a probe that is directed by a three-dimensional, computerized navigation system. The computerized system matches the MRI and CT images of the tumor to the person’s brain. This allows doctors to locate a tumor as well as nearby structures within the brain to avoid damage during surgery.

After the doctor performs the biopsy, he or she sends the tumor tissue to a laboratory for analysis. A pathologist, a doctor who studies diseases under a microscope, examines the tissue to determine the grade of the glioma, which helps the doctor create a treatment plan. This procedure may be performed at the same time as surgery to remove the tumor.

Stereotactic biopsy sometimes requires a frame that is fixed to a person’s head before imaging and surgery to ensure the head does not move during the procedure. Most times, no frame is necessary.

Our neuropathologists perform precision molecular DNA testing, a sophisticated analysis of the DNA mutations in the tumor. This provides a precise molecular diagnosis that helps better predict a prognosis than traditional pathology tests, and may also predict how well the tumor responds to various treatments. Precision molecular diagnosis allows our doctors to personalize a treatment plan for you.