How We Diagnose Brain Tumors

At the Center for Neuro-Oncology at Dana-Farber Brigham Cancer Center, we understand that waiting for a formal diagnosis is a difficult time for you and your family. Our experts work together efficiently to complete the multi-step process and reach a precise diagnosis as quickly as possible, so that you can start your treatment without delay.

To establish an accurate diagnosis, you will undergo a series of tests based on your symptoms, the location and nature of your tumor, and your personal health history. You may receive an array of standard and unique diagnostic imaging procedures, which will be analyzed by your team for treatment planning.

Since our neuro-oncology clinicians focus solely on the treatment of brain tumors, spinal cord tumors, and neurological complications from cancer, they have deep expertise in diagnosing and treating all forms of brain tumors, even rare types. And our multidisciplinary approach to diagnosis and treatment means that all resources will be engaged for each patient's unique situation.

Complex brain cancer cases requiring multidisciplinary care are reviewed by the brain tumor diagnostic board and the treatment tumor board at weekly meetings that include representatives from all neuro-oncology clinical specialties. Results of all tumor tissue pathology tests are reviewed, and approaches to treatment are discussed.

Diagnostic Testing

Tests that examine the brain and spinal cord to help diagnose adult brain and spinal cord tumors include:

  • Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
  • Neurological exam: A series of questions and tests to check the brain, spinal cord, and nerve function. The exam checks a person's mental status, coordination, and ability to walk normally, as well as how well the muscles, senses, and reflexes work. This may also be called a neuro exam or a neurologic exam.
  • Visual field exam: An exam to check a person's field of vision (the total area in which objects can be seen). This test measures both central vision (how much a person can see when looking straight ahead) and peripheral vision (how much a person can see in all other directions while staring straight ahead). Any loss of vision may be a sign of a tumor that has damaged or pressed on the parts of the brain that affect eyesight.

If your medical oncologist believes there may be a brain tumor present based on these test results, diagnostic imaging will be performed and analyzed in collaboration with our neuroradiologists.

Diagnostic Imaging

At the Center for Neuro-Oncology, diagnostic imaging is central – before, during, and after treatment. Standard and unique imaging allow your clinical team to learn more about the characteristics of a brain tumor, as well as determine which areas of the brain are affected and which healthy tissue to avoid for the best and safest approach to treatment. All patients with a suspected brain tumor routinely have diagnostic scans within 48 hours. Specialized neuroradiologists assess your diagnostic imaging with your medical oncologist to best determine the next step in your treatment plan.

Imaging Techniques and Procedures

  • CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an X-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
  • PET scan (Positron Emission Tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the brain. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells. PET is also sometimes used to tell the difference between a growing tumor and inflammation from treatments such as radiation.
  • MRI (Magnetic Resonance Imaging) with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of the brain and spinal cord. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI). Sometimes an additional procedure called magnetic resonance spectroscopy (MRS; see bullet below) is done during the MRI scan. The MRS is used to diagnose tumors, based on their chemical make-up. MRI is often used to diagnose tumors in the spinal cord.
  • Advanced MRI: Advanced MRI techniques determine the tumor's proximity to critical areas of the brain and identify other important tumor characteristics – information essential to devising the best treatment approach. These techniques include:
    • Functional MRI (fMRI): Maps areas of the brain responsible for critical functions, such as movement and speech. An fMRI also measures blood flow and activity throughout the brain.
    • Diffusion tensor imaging (DTI): Identifies white matter tracts, the signaling pathways in the brain. This procedure helps our specialists determine the cellularity, nature, and structure of a brain tumor and is used in preoperative planning.
    • Magnetic resonance spectroscopy (MRS): Measures biochemical changes in the brain, especially in the presence of brain tumors. This procedure serves as a biomarker, meaning it is a measurable indicator of a tumor's progression and growth. MRS provides details on specific tumor characteristics and type, as well as on tumor metabolism. It is useful in determining the tumor's boundaries to achieve complete tumor removal/treatment during surgery.
    • Perfusion MRI: Allows our specialists to examine the grade and blood volume of the brain tumor.
    • Hemosiderin Imaging: Identifies the presence of occult blood in the brain; completed in two sequences.
  • Diagnostic angiogram: A procedure that creates a map of how blood vessels look and the flow of blood in the brain. A contrast dye is injected into the blood vessel and as it moves through the blood vessel, X-rays are taken to see if the vessel is blocked.
  • Myelogram: A procedure that uses contrast dye and X-rays to identify problems in the spinal cord.

Some of these tests and procedures may be repeated after treatment to find out how much tumor remains, or to plan further treatment.

Biopsy and Grading of Brain Tumors

If imaging tests confirm that a brain tumor or mass is present, a biopsy is typically performed. A biopsy removes a very small piece of the tumor tissue to determine the tumor type. The tumor sample is analyzed by our neuropathologists in collaboration with your medical oncologist and neurosurgeon.

For certain tumors, a biopsy or surgery cannot be done safely because of where the tumor has formed in the brain or spinal cord. These tumors are diagnosed and treated based on the results of imaging tests and other procedures. Sometimes the results of imaging tests and other procedures show that the tumor is very likely to be benign, and a biopsy is not done.

One of the following types of biopsies may be performed to diagnose your tumor:

  • Stereotactic biopsy: When imaging tests show there may be a tumor deep in the brain, a stereotactic brain biopsy may be performed. This kind of biopsy uses a computer and a 3-dimensional scanning device to find the tumor and guide the needle used to remove the tissue. A pathologist vies cells or tissue from the biopsy under a microscope to check for signs of cancer.
  • Open biopsy, craniotomy: When imaging tests show that a tumor can be removed by surgery, an open biopsy may be done. Part of the skull and a sample of brain tissue is removed and viewed under a microscope by a pathologist. If cancer cells are found, some or the entire tumor may be removed during the same surgery. Tests are done prior to surgery to find the areas around the tumor that are important for normal brain function. Brain function is also tested during surgery. Using these tests, the neurosurgeon will remove as much of the tumor as possible with the least damage to normal brain tissue.

WHO Tumor Grading System for Adult Brain Tumors

Brain and spinal cord tumors are named based on the type of cell they formed in, and where the tumor first formed in the central nervous system. While the extent or spread of most cancers is usually described in terms of stages, there is no standard staging system for brain and spinal cord tumors. A tumor is graded based on whether it is slow-growing or fast-growing.

The World Health Organization (WHO) grades tumors based on how the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Brain tumors are categorized or graded on a scale of I to IV, with I being low-grade (slow-growing) and IV being high-grade (rapidly growing).

  • Grade I (low-grade): The tumor grows slowly, has cells that look a lot like normal cells, and rarely spreads into nearby tissues. Grade I brain tumors may be cured if they are completely removed by surgery.
  • Grade II: The tumor grows slowly, but may spread into nearby tissue and may recur (come back). Some tumors may become a higher-grade tumor.
  • Grade III: The tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.
  • Grade IV (high-grade): The tumor grows and spreads very quickly, and the cells do not look like normal cells. There may be areas of dead cells in the tumor. Grade IV tumors usually cannot be cured.


At the Dana-Farber Brigham Cancer Center's Center for Neuro-Oncology, we approach cancer diagnosis through precision cancer medicine, which characterizes the genetic and molecular abnormalities in each specific brain tumor. Since we now know that all or most cancer results from abnormal genes or gene regulation, new knowledge regarding the pathogenesis (disease development) of a cancer can pinpoint diagnosis exactly, and target therapy precisely. Each of our neuropathologists specializes in the research of a specific brain tumor type, providing you with the most expert approach to the diagnosis of your brain tumor.

All patients' brain tumor tissue not only undergoes the standard pathology exams to provide a precise diagnosis, but also a number of pioneering tests and scans for mutated genes and misassembled chromosomes, as well as whole-genome searches for surplus or missing copies of genes. Such extensive multi-testing genetic profiling identifies the type and characteristics of a particular tumor, and is part of the standard diagnostic process at the Center for Neuro-Oncology. All tests are ordered immediately by your neuropathologist, with results available within one to two weeks, depending on the types of tests that are needed.

Tumor tissue from brain cancer patients at the Center for Neuro-Oncology is carefully evaluated by our pathology experts in collaboration with the treating physicians to give expert opinion on what tests are most important to apply to your valuable tissue specimen. In most cases, the tissue undergoes at least four categories of cellular and molecular tests, including:

  • Conventional histopathology analysis: The tissue is examined under a microscope to generate the initial diagnosis within a matter of days.
  • Immunohistochemistry test: A test that focuses on cell proteins, called antigens, that signal a specific type of cancer. The antibody is usually linked to a radioactive substance or a dye that causes the tissue to light up under a microscope. This type of test may be used to tell the difference between different types of cancer.
  • OncoCopy: A whole-genome scan that can powerfully detect extra or missing copies of certain genes, particularly those that are targeted by molecular therapies.
  • OncoPanel: This examines the protein-coding portions of genes to identify mutations associated with cancer. OncoPanel is part of a unique Profile program at Dana-Farber Brigham Cancer Center that analyzes tumor tissue for known cancer-related mutations. These are frequently used to "match" the mutation to the correct targeted therapies. Learn more about genotyping and OncoPanel.
  • Tumor marker test: A procedure in which a sample of blood, urine, or tissue is checked to measure the amounts of certain substances made by organs, tissues, or tumor cells in the body. Certain substances are linked to specific types of cancer when found in increased levels in the body. These are called tumor markers. This test may be done to diagnose a germ cell tumor.
  • Gene testing: A laboratory test in which a sample of blood or tissue is tested for changes in a chromosome that has been linked with a certain type of brain tumor. This test may be done to diagnose an inherited syndrome.
  • MGMT promoter methylation testing: A key epigenetic test that can predict clinical outcomes, particularly in glioblastoma patients.
  • Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes by FISH or karyotype testing.

Description and Diagnosis by Tumor Type


Glioblastoma, or glioblastoma multiforme, is an aggressive grade IV, CNS (central nervous system) tumor that grows and spreads very quickly. It is the most common primary brain cancer in adults. It can occur at any age, but is more common as we get older. The diagnosis of a glioblastoma includes a neurological exam, diagnostic imaging, and a biopsy or surgery.

Lower-Grade Gliomas

Lower-grade gliomas are less aggressive and slower growing tumors, graded either I or II. Gliomas are usually seen in younger patient populations and are named for the type of brain cell that they resemble. Two common types of gliomas are astrocytomas and oligodendrogliomas. Some gliomas have features of both and are known as oligoastrocytomas or mixed gliomas. The diagnosis of low-grade gliomas includes a neurological exam, diagnostic imaging, and a biopsy.

Because low-grade gliomas can be difficult to see in the brain, the magnetic resonance spectroscopy (MRS) and metabolic imaging techniques that our experts use to learn more about lower-grade gliomas are essential to preoperative planning. Our highly skilled neurosurgeons are able to use the intraoperative MRI technology available in our AMIGO Suite to better approach the removal of these tumors.

Primary CNS (Central Nervous System) Lymphoma

Primary CNS lymphoma is a very rare tumor type that accounts for less than three percent of all brain tumors and is typically a high-grade tumor. Primary CNS lymphoma can be found in the brain, the spinal cord, the leptomeninges, or the eye. The diagnosis involves a physical exam, neurological exam, imaging of the brain or spine (depending on the patient's symptoms), and a specific biopsy based on the location of the tumor. The diagnosis is made either by a brain biopsy or by evaluating the spinal fluid, if the spinal fluid is thought to be involved. If the tumor is isolated only in the eye, or if the eye seems to be involved and is easier to reach than the areas of the brain affected, a vitreous biopsy may be performed.

Once the diagnosis is made, our experts will confirm that it is, in fact, primary and not secondary. A CAT scan and PET scan of the whole body are performed to make sure there are no other affected areas. Patients undergo a bone marrow biopsy, and their spinal fluid is tested. The eyes are checked by a slit-lamp exam to confirm that there are no cells inside the eye.

Learn about our CNS Lymphoma Center, the first of its kind in the world dedicated to providing comprehensive care and research for patients with primary or secondary CNS (central nervous system) lymphoma.

Brain Metastases (Secondary Brain Tumors)

Brain metastases, or secondary brain tumors, originate from a primary cancer in another part of the body, and are more common than primary brain tumors. Up to 40 percent of cancer patients develop brain metastases; they are most common in middle-aged adults. Metastatic brain tumors are diagnosed with a physical exam, a neurological exam, and MRIs and other imaging techniques. Our multidisciplinary neuro-oncology team works closely with the team of a patient's primary cancer to ensure seamless treatment.

Learn about our Brain Metastases Program, one of the most comprehensive programs in the United States for patients whose cancer has metastasized to the brain.


A meningeal tumor, also called a meningioma, forms in the meninges – thin layers of tissue that cover the brain and spinal cord. It can form from different types of brain or spinal cord cells. The diagnosis of a meningioma involves a physical exam, a neurological exam, diagnostic imaging, and a biopsy. Meningiomas are most common in adults and can be grades I, II, or III. A grade I meningioma, which is the most common type, is a slow-growing tumor that can be cured if it is completely removed by surgery. Grade II and III meningiomas are rare. They grow quickly and are likely to spread within the brain and spinal cord. Most people with a meningioma will have a tumor at only one site, but it also is possible to have several tumors growing simultaneously in different parts of the brain and spinal cord. When multiple meningiomas occur, more than one type of treatment may be necessary.

Second Opinions

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Consultations and Second Opinions

A second opinion can ensure the most precise diagnosis and subsequent treatment options. If you have already received a diagnosis from your doctor, getting a second opinion from our neuro-oncology experts is simple and does not require you to schedule an in-person visit to Dana-Farber Brigham Cancer Center.

If you would like a second opinion, ask your physician to send a summary of your diagnosis and your pathology slides directly to us. Our expert neuropathologists will examine and evaluate your slides to provide the most precise diagnosis of your condition.

For more information on requesting a second opinion at the Center for Neuro-Oncology, please call 617-632-3703. Or complete the Appointment Request Form

If you cannot travel to Boston in person, you can take advantage of our Online Second Opinion service.

Can't travel to Boston? Our Online Second Opinion service lets patients from all over the world receive expert second opinions from Dana-Farber oncologists.

For Referring Physicians

Because you, the referring physician, are an integral part of your patient's care team, we are committed to collaborating with you to provide the best care for your patient.