Diagnostic Tests for Astrocytoma

Doctors use several tests to diagnose astrocytomas. Your doctor will ask about your medical history, including any prior illnesses that might have weakened your immune system or involved radiation therapy. Your doctor will also ask about your family history, your habits, and your lifestyle.

Doctors use a neurological exam to diagnose astrocytomas. During this exam, your doctor looks for changes to your vision, hearing, balance, coordination, strength, and reflexes. These changes can identify which part of your brain may be affected by a tumor.

Imaging tests that take pictures of your brain also help diagnose astrocytomas. Doctors use a variety of imaging technologies, each offering insights to confirm the presence, location, and type of tumor that may be present. They may also take a sample of the tumor.

MRI to diagnose astrocytoma
Magnetic resonance imaging (MRI) is the most common imaging doctors use to diagnose brain tumors. This test uses radio waves and magnets to create images of brain structures. A technologist or nurse may perform this scan by injecting contrast dye into your arm to illuminate the tumor’s location. Doctors use 2 main types of MRI to diagnose glioblastoma:

• Functional MRI: Maps brain activity by evaluating the structures of the brain and detecting changes in blood flow
• Perfusion MRI: Identifies parts of the brain with less blood flow, a potential sign of a tumor blocking the path
• Tractography: Visualizes white matter tracts which carry electric signals and sensory information for the central nervous system. These images are uploaded to neurosurgical navigation system in the operating room to guide the surgeon around critical pathways as the tumor is removed.

CT scan to diagnose astrocytomas
Some people cannot have an MRI because the magnets interfere with implanted medical devices such as pacemakers and cochlear implants. Computed tomography (CT) scans take combine multiple X-rays and provide doctors with another way to see structures in the brain.

Biopsy to diagnose a low grade glioma
Your doctor may perform a biopsy to confirm diagnosis of astrocytoma. A biopsy also provides information to help guide treatment decisions.

During a biopsy, your doctor uses a small needle to remove cells from the tumor. Doctors look at the cells under a microscope to confirm that the sample tissue is cancerous. Based on this information, a pathologist determines the grade of the tumor, which indicates how aggressive it is.