Imaging & Testing
When a brain tumor is suspected, the road to diagnosis often involves a combination of advanced imaging and a biopsy. These steps not only confirm the presence of a tumor but also help determine its type, grade, and how it may behave over time. Understanding the full diagnostic process can help you or a loved one feel more informed and prepared.
Imaging: The First Step
Doctors typically begin with brain imaging if symptoms or other clinical signs suggest a possible tumor. Imaging tests offer a non-invasive way to visualize any abnormalities in the brain.
MRI Scan (Magnetic Resonance Imaging)
An MRI scan is the most effective and preferred imaging tool to diagnose brain tumors. It uses magnetic fields—not x-rays—to create detailed images of the brain’s structure. This level of detail allows doctors to:
- Identify the tumor’s location and size
- Distinguish between tumor and healthy tissue
- Plan next steps in diagnosis or treatment
A contrast dye, often injected into the bloodstream, may be used to enhance the clarity of the scan. The MRI procedure typically lasts about an hour and requires the patient to lie still in a cylindrical machine.
CT Scan (Computed Tomography)
A CT scan is a fast, painless imaging test that creates 3-D images of the brain using x-rays. While it provides less detail than an MRI, it may be used in emergency settings or for patients who cannot undergo an MRI. Like MRIs, CT scans may also use a dye for enhanced contrast.
PET Scan (Positron Emission Tomography)
PET Scan (Positron Emission Tomography)
A PET scan is sometimes used to evaluate how a brain tumor is affecting activity, metabolism, or blood flow in the brain. A small amount of radioactive tracer (such as glucose or amino acids) is injected into the bloodstream, and a scanner tracks how it moves through the brain.
Lumbar Puncture (Spinal Tap)
In some cases, a lumbar puncture is performed to examine cerebrospinal fluid (CSF) for tumor cells. This is particularly helpful in diagnosing tumors that affect the brain’s surrounding tissues or spread through the CSF.
Lumbar Puncture (Spinal Tap)
In some cases, a lumbar puncture is performed to examine cerebrospinal fluid (CSF) for tumor cells. This is particularly helpful in diagnosing tumors that affect the brain’s surrounding tissues or spread through the CSF.
Testing: Confirming Diagnosis
Testing of brain tumors is essential because it helps determine the exact type, grade, and genetic makeup of the tumor, which guides doctors in choosing the most effective treatment plan. Accurate testing can reveal biomarkers or molecular alterations that influence how a tumor behaves and responds to specific therapies, leading to more personalized and targeted care. Below are examples of the types of testing that can be done on tumors:
Biopsy Procedure
While imaging can strongly suggest the presence of a brain tumor, a biopsy is the only way to confirm the diagnosis. A biopsy involves surgically removing a small portion of tumor tissue to be examined under a microscope or tested for molecular markers.
Once removed, it is sent to pathology, where stains will be applied, and it will be reviewed under a microscope to determine the cell type.
Once the tumor tissue is analyzed, your doctor can determine:
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- The type of tumor (based on the kind of cell it developed from)
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- The grade of the tumor (how aggressive it appears to be)
Genetic Markers
Every brain tumor has its own genetic “fingerprint.” Doctors learn about these fingerprints by studying the tumor’s tissue after surgery or biopsy. This testing, called molecular profiling, helps them understand what makes the tumor grow and how it might respond to certain treatments.
Learn more about the types of genetic mutations here.
What Comes Next
Once your doctor determines the tumor type and grade, they’ll work with you to create a personalized treatment plan. This plan may include the standard of care: surgery, radiation therapy, and chemotherapy. Or targeted treatments based on genetic or molecular findings from the biopsy.