If your doctor is concerned that a brain tumor is causing your symptoms, your doctor may conduct tests to find out more about the tumor’s size, type, and location. Understanding these tests – how they work, why they are done, and what they can show – can help you be an informed member of your care team. If you have any questions about the tests your doctor is ordering, ask your doctor, nurse, patient navigator, or other health care professional.
As you go through your brain tumor journey, your doctor may repeat some of these tests to find out if the tumor has changed and if it is responding to treatment.
A neurological exam is usually the first step toward figuring out what is causing your symptoms. The goal is to see how well your nervous system is working. Because your brain does so many different things, a neurological exam can have many different parts. Your doctor may repeat the neurological exam many times throughout your brain tumor journey, to see whether your symptoms are changing.
During a basic neurological exam, your doctor evaluates how well your nerves, balance, reflexes, strength, and senses are working. Your doctor will also assess your cognitive functioning and mental or emotional state.
Here are some common parts of a neurological test:
- Eye test: Check vision, assess how well your eyes follow a moving object, how quickly your pupils react to light, and whether or not your eyes move together when your head turns from side to side. A light may be used to look into your eye and view the ocular (a nerve that runs from the eye to the brain) and retina.
- Hearing test: Evaluate your hearing using a ticking watch, tuning fork, or another tool.
- Reflex test: Gently tap just below your ankles, kneecaps, and other joints with a rubber hammer to check your reflexes.
- Balance and coordination test: Ask you to walk heel to toe; balance with your feet together and eyes closed; or close your eyes, extend your arms out to the side, and touch your nose with the tip of one finger.
- Sense of touch test: Ask you to hold an object (like a cotton ball or a paint brush) and describe how it feels.
- Sense of smell test: Ask you to describe how something smells, such as rubbing alcohol or a sweet liquid.
- Facial muscle test: Ask you to make faces such as a smile, frown, or grimace.
- Tongue movement and gag reflex tests: Check your swallow response by asking you to move your tongue and testing your gag reflex.
- Head movement test: Move your head into various positions in order to find out more about any issues with balance or mobility.
- Mental status tests: Ask questions, such as “What is the current day, season, and year?”
- Abstract thinking tests: Ask you to explain a common saying, such as “A penny saved is a penny earned.”
- Memory tests: Ask you to repeat a list of objects, describe what you ate for breakfast yesterday, or talk about how you celebrated last Thanksgiving.
If your neurological exam results lead your doctor to suspect that a brain tumor is causing your symptoms, your doctor may order additional tests, including imaging, or blood tests. Your doctor may also refer you to a neurologist (a physician who specializes in brain and central nervous system problems) or neuro-oncologist (a doctor who specializes in cancer of the brain and the rest of the nervous system).
A brain scan is a type of diagnostic test that takes pictures of the brain. Like an X-ray can see inside the body to diagnose a broken bone, a brain scan can see inside the skull to see a brain tumor. The two most common scans for diagnosing a brain tumor are magnetic resonance imaging (MRI) and computed tomography (known as a CT or CAT scan).
During your scan, your doctor may use a special dye, called contrast, to make areas of the brain easier to see. Contrast material is usually injected into a vein before the scan starts. The radiology (the science dealing with X-rays and other high-energy radiation, especially the use of such radiation for the diagnosis and treatment of disease) facility performing the test will provide information about your test, including any information and instructions about the contrast agent (if prescribed), what to wear, and what to bring along. The radiology facility will determine if you need a blood creatinine test (a test that shows the level of creatinine in your blood and provides an estimate of how well your kidneys filter) to ensure your kidneys are safe to receive contrast. Let the facility know if you have any allergies.
Brain scans are non-invasive (a noninvasive procedure is one that does not involve cutting into the body or removing tissue) and generally painless. The hardest part is having to sit or lie still for a long time, and some patients need medicines for claustrophobia. It is a good idea to bring layered clothes, water, and your routine pain medicine.
Computed Tomography (CT)
The CT scanner is a large donut-shaped piece of equipment. This scan combines high-speed X-ray technology with a computer. The patient lies on a table that slides into an opening in the CT machine. The CT scanner circles the head, taking X-rays from every angle. The computer then combines these thousands of X-ray images into a cross-sectional image of the brain (sometimes called a “slice”).
Magnetic Resonance Imaging (MRI)*
The MRI scanner is a tunnel-shaped piece of equipment that uses magnets and radio waves to generate pictures of the brain tissue. The patient lies on a table that slides into the scanner, where a magnetic field surrounds the head. MRIs can create two-dimensional or three-dimensional pictures of the brain. Unlike CT scans, MRIs do not use radiation.
Functional MRI (fMRI)*
fMRIs produce MRI images in a faster sequence than traditional MRI. The increased speed shows how oxygen is used in the brain. fMRIs are sometimes used before or during surgery to indicate which areas of the brain control important functions so that the surgeon can avoid disturbing those areas.
Flow-Sensitive MRI (FS MRI)*
This technique combines functional MRI with images of cerebrospinal fluid (CSF) (a colorless liquid that fills and surrounds the brain and the spinal cord) flow. FS MRIs are particularly useful in planning surgery to remove a skull base tumor, spinal cord tumor, or a tumor causing hydrocephalus (fluid buildup on the brain).
Dynamic CT or Dynamic MRI (also called perfusion MRI)*
Advances in computer technology have made it possible to use existing scanning equipment to measure cerebral blood volume (CBV), cerebral blood flow (the blood supply to the brain over a certain period of time) (CBF), and blood vessel leakage. The scanner begins taking pictures immediately after contrast is injected, allowing doctors to see the way the contrast material is moving through the blood vessels in the brain. This can be used to detect blood vessel injury, such as a cerebrovascular accident (stroke), and to distinguish between active tumor blood vessels verses injured brain blood vessels.
Angiography and Magnetic Resonance Angiography (MRA)*
Angiography uses rapid X-rays to outline the presence and position of blood vessels in the brain. MRA uses a rapid series of MRI scans to follow the blood flow through the vessels, with or without contrast.
Magnetic Resonance Spectroscopy (MRS)*
MRS produces images that show function rather than shape. This technique can show patterns of brain activity that may help diagnose specific tumors and conditions. MRS may also be used to determine how advanced a tumor is.
Positron Emission Tomography (PET, FDG-PET)
PET scans are not usually used for diagnosis, but they can help your doctor estimate the tumor’s grade. In some cases, it may also be used to tell the difference between recurrent tumor cells, cells killed by radiation, or scar tissue. The PET machine looks similar to a CT scanner. Before the test, you will ingest a small amount of radioactive material (called a “tracer”), and then wait several hours before being scanned. The areas where the tracer collects will show up as bright spots on the scan. The tracer leaves the body quickly and does not pose a safety risk to you or your loved ones. The radiology facility will provide information before the test.
Single Photon Emission Computerized Tomography (SPECT):
SPECT is not usually used to diagnose brain tumors. However, it sometimes provides data that complements information captured in other scans.
*For these tests, the radiology facility will ask you to complete a form determining if they are safe. For instance, metal objects implanted in your body or kidney disease can pose safety risks.
During the diagnostic process, your doctor will probably order some laboratory tests, usually blood and urine tests. Some lab tests confirm the presence of a brain tumor or whether a tumor is growing or shrinking. Other tests check the status of your general health or show how well medications and treatments are working.
The laboratory facility will provide you information about the tests, including things you need to do to prepare. If you have questions about the reason for a particular lab test, talk with your doctor beforehand. Your doctor can also discuss the meaning of lab test results.
In recent years, biomarkers have been used to identify certain tumors. Biomarkers are other distinct cellular materials, such as proteins or DNA from brain tumor cells. These biomarkers can be collected in the blood, urine, cerebral spinal fluid, saliva, or brain tissue. These tiny bits of genetic material are being explored for their potential use in the diagnosis, treatment, and monitoring of the effectiveness of medications in patients with brain tumors.
Lumbar Puncture (LP, also called a Spinal Tap)
This procedure is used to obtain a sample of cerebrospinal fluid (CSF) from the spinal canal. To do this, your doctor will insert a thin, hollow tube between two vertebrae in your lower back (lumbar).
The CSF sample is examined in a lab to determine if tumor cells, tumor biomarkers, infection, protein, or blood is present.
Measurements of hormone levels in blood and/or urine samples can help doctors diagnose pituitary or hypothalamic tumors.
A pathology report is a document that summarizes key information about your tumor. A pathologist (a physician who interprets and diagnoses the changes caused by disease in tissues and body fluids) examines and analyzes the tumor tissue, typically during a biopsy. These results not only help doctors specifically characterize your tumor, but also help them determine the status of your tumor, plan tumor-specific treatments, and predict the tumor’s response to treatment.
Here are common parts of a pathology report:
- General information: patient’s name, doctor’s name, date, and details about the tumor specimen
- Gross description: what the tumor looks like to the naked eye
- Microscopic description: what the pathologist sees under the microscope. This includes important details about the tumor, like:
- Whether it is invasive (growing into nearby parts of the brain) or in situ (non-invasive)
- Tumor grade
- Mitotic rate – how quickly the tumor cells are dividing
- Tumor margin – whether there are abnormal cells at the edge of the tumor. A “positive” tumor margin means that it is likely that abnormal cells are still in the body
- Diagnosis – the summary of the findings: the “bottom line”
Pathology testing is becoming increasingly complex and is customized for each patient. It is important that you review your pathology reports with your doctor.
Test results often take time to be completed, so ask your doctor for an update. For instance, the “final report” (traditionally defined as the World Health Organization’s definition of your tumor category) is usually NOT the complete set of tests requested by your doctor. To get a copy of your pathology reports, you can contact the medical records department of the hospital where your tumor tissue was obtained.
A biopsy is a surgical procedure in which the surgeon removes a small amount of tumor tissue and sends it to the lab for a pathologist (a physician who interprets and diagnoses the changes caused by disease in tissues and body fluids) to evaluate. In some cases, a biopsy is performed after surgical removal of the tumor. In other cases, the biopsy is a separate procedure.
The purpose of a biopsy is to establish an exact diagnosis.
Under general anesthesia, the surgeon makes a small cut in the scalp and drills a small hole (called a burr hole) into the skull. The surgeon then inserts a thin, hollow needle through the hole and collects a sample of tumor tissue through the needle’s core.
This minimally invasive procedure is the same as a needle biopsy, but the surgeon uses a computer-assisted guidance system. The computer uses 3D images and data from a CT or MRI scan to provide precise information about a tumor’s location and its position relative to the brain’s many structures.
During the procedure, stereotactically-guided equipment (equipment that uses 3D images to help guide the physician to the site of the tumor) is moved into the burr hole to remove a tumor tissue sample.
During a resection (surgical removal of a tumor), the surgeon takes the tumor tissue sample during an operation while the tumor is exposed. This generally requires the surgeon to remove a piece of the skull to access the tumor.
Genetic testing is a tool used to identify brain tumor subtypes and/or biomarkers. These lab tests identify the tumor’s DNA profile – its unique genetic fingerprint – from tissue collected during a biopsy or resection (surgical removal of a tumor). In some cases, this information can be used in treatment to target an individual’s specific tumor (precision medicine).
Your doctor may also send a sample of your blood for DNA sequencing. Some genetic changes (mutations) are associated with brain tumor development, and looking at your individual genome (your complete set of genes) may help your care team understand more about your tumor.
If your doctor or treatment center says genetic testing is not available, seek a second opinion at a brain tumor center that offers genetic testing.
This test is used primarily to diagnose a spinal tumor and to help in planning spinal tumor surgery, although spinal MRI has replaced myelography in many instances.
Before a myelogram, a special dye is injected into the spinal column through a lumbar puncture. The patient is then tilted to allow the dye to mix with the CSF.
Evoked-potential testing uses small electrodes to measure a nerve’s electrical activity. This test is particularly helpful in diagnosing a vestibular schwannoma (acoustic neuroma) affecting the inner ear. Evoked-potentials can also be used to monitor neurological function during surgery to remove the tumor.
A hearing test that is useful in diagnosing tumors that arise in the posterior fossa (lower back part of the skull) such as vestibular schwannoma (acoustic neuroma), cranial nerve schwannoma, or skull base meningioma.
This noninvasive eye test measures the size of the visual fields, including your peripheral vision. A visual acuity (an eyesight test, measuring how sharp your vision is relative to the 20/20 standard) examination and examination for tumor cells, if relevant, are also performed at this time. To complete the test, you look at a screen and press a button when you see lights flashing. Perimetry data can help diagnose a tumor near the eyes.