Diagnosis of brain tumor

Executive Summary

A brain tumor is diagnosed based on signs and symptoms. The brain tumour diagnosis relies on the type of tumor, such as benign or malignant. There are different types of tests for the diagnosis of brain tumor. A neurologist often diagnoses brain tumors. Diagnosis of brain tumor usually begins with magnetic resonance imaging (MRI). Once an MRI shows a tumor in the brain, the most common way to determine the type of brain tumor is to look at the results of a biopsy or surgery. The diagnostic approaches for brain tumors involve different types of MRIs such as intravenous (IV) gadolinium, spinal MRI, functional MRI, and magnetic resonance spectroscopy. Other diagnostic tests include tissue sampling (biopsy, surgical tumor removal), computed tomography (CT) scan, positron emission tomography (PET) or PET scan, cerebral arteriogram, lumbar puncture or spinal cord, myelogram, biomarker testing tumor, oligodendroglioma, isocitrate dehydrogenase (IDH), glioblastoma, neurological, vision, and hearing tests, neurocognitive, electroencephalography (EEG), and evoked potentials.

Diagnosis of Brain Tumor

Many tests are performed to find the Diagnosis of a brain tumor ​1​. Also, tests are done to learn if the brain tumor has spread to parts other than it started. The spread of the tumor to other regions is called metastasis and is rare for primary brain tumors.

A biopsy is a sure way to know if you have cancer in a particular part or organ of the body for most types of cancer.

Imaging tests can help doctors determine if the tumor is a primary brain tumor or if cancer has metastasized to the brain from elsewhere in the body.

The different tests can be used for a person depending upon the following factors – 

  • Your signs and symptoms
  • The age and general health status
  • The type of cancer suspected
  • The result of earlier medical tests

Brain tumors are diagnosed mainly after the appearance of the symptoms. Brain tumors are often diagnosed by a neurologist (a doctor who treats problems related to the CNS).

The doctor asks the patient for a detailed medical history and physical examination and can recommend the tests described below. These tests help determine a brain tumor’s presence and sometimes the type or grade.

In general, the brain tumor diagnosis usually begins with magnetic resonance imaging (MRI). Once an MRI shows a tumor in the brain, the most common way to determine the type of brain tumor is to look at the results of a biopsy or surgery.

These tests and procedures are explained below in more detail.

Magnetic resonance imaging (MRI)

An MRI uses magnetic fields, not x-rays, to produce detailed body images. A specific dye known as contrast medium is given before the scan to create a better picture. MRIs create more detailed images than CT scans and are the preferred way to the Diagnosis of brain tumor. The MRI can be of the brain, spinal cord, or both, depending on the type of tumor suspected and the likelihood that it will spread in the CNS. There are different types of MRI:

Intravenous (IV) gadolinium

Intravenous (IV) gadolinium enhanced MRI is usually used to help create a clearer picture of a brain tumor. 

Spinal MRI

A spinal MRI is used for the diagnosis of a tumor on or near the spine.

Functional MRI (fMRI)

A Functional MRI (fMRI) provides information about specific areas of the brain responsible for the movement of muscle and speech. In the fMRI examination, the patient is asked to do specific tasks that lead to changes in the brain and are shown on the fMRI image. 

Magnetic resonance spectroscopy

Magnetic resonance spectroscopy is a test using an MRI that provides information on the brain’s chemical composition. It can tell the difference between any dead tissue caused by previous radiation treatments and new tumor cells in the brain ​2​.

Tissue sampling/ Biopsy/ surgical removal of tumor

A biopsy removes a small part of tissue to examine under a microscope. A biopsy can also be done as part of surgery to remove the entire tumor. Surgery may be performed as a separate procedure if completely removing the tumor is not possible because of its position or a patient’s health.

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The health care team can also recommend other tests that help make a the Diagnosis of brain tumor or know how well treatment is working. Not all tests will be used for every person.

CT scan

A CT scan clicks pictures of the body from inside using x-rays taken from different angles. A computer combines photos into a detailed, 3-dimensional image that shows abnormalities or tumors. A CT scan can help find bleeding and extension of the fluid-filled spaces in the brain, called ventricles. Changes in the skull bone can also be seen on a CT scan, and it can be used to measure a tumor’s size.

Positron emission tomography (PET) or PET-CT scan

A PET scan creates images of organs and tissues present inside the body. A small proportion of radioactive substance is injected into the patient’s body which is taken up by cells using the most energy. The cancer cells which use energy actively take up the radioactive substance, and the scanner then spots this substance to produce images of the inside of the body.

Cerebral arteriogram

A cerebral arteriogram also called a cerebral angiogram, is an x-ray of the head that shows the arteries present in the brain ​3​. X-rays are taken after a particular dye called a contrast medium is injected into the main arteries of the patient’s head.

Lumbar puncture or spinal tap

A lumbar puncture is a procedure where a needle is used to draw a sample of cerebrospinal fluid (CSF) in search of tumor cells or tumor markers ​4​


Myelogram can be recommended to find if a tumor has spread to spinal fluid or other parts of the brain. A myelogram uses a dye injected into the CSF that surrounds the spinal cord. The dye shows up on the x-ray and can outline the spinal cord to help the doctor look for a tumor.

Biomarker testing of tumor

Your doctor may recommend you to take laboratory tests on a tumor sample to identify proteins, specific genes, and other factors, such as tumor markers, unique to the tumor. This is called molecular testing of the tumor. 


For oligodendroglioma, the loss of the p-arm of chromosome 1 and the q-arm of chromosome 19. It is called a 1p/19q co-deletion. It can be used in planning treatment, especially for anaplastic oligodendroglioma ​5​.

Isocitrate dehydrogenase (IDH)

An Isocitrate dehydrogenase (IDH) gene mutation in adults with about 70% to 80% of low-grade gliomas ​6​. Higher-grade tumors can also have IDH gene mutations, which suggests that these tumors started as lower-grade tumors that became a higher grade. This mutation is associated with a finer prognosis in both low-grade and high-grade tumors.


In glioblastoma, changing a gene called methyl guanine methyltransferase (MGMT) can help understand a patient’s prognosis and know how well the treatment can work. 

Neurological, vision, and hearing tests

These tests help identify Diagnosis of brain tumor that’s if a tumor affects brain functions. An eye examination detects changes to the optic nerve and changes to a person’s field of vision.


Neurocognitive assessment consists of a detailed evaluation of all primary functions of the brain, like storage and retrieval of memory, expressive and receptive language abilities, calculation, dexterity, and the patient’s overall well-being.

Electroencephalography (EEG)

An Electroencephalography (EEG) is a noninvasive test in which electrodes are attached to the outside of a person’s head to measure the brain’s electrical activity. It is used to monitor possible seizures. 

Evoked potentials

Evoked potentials use the electrodes to measure the electrical activity of nerves and can detect acoustic schwannoma, a noncancerous brain tumor. This test can be used as a lead while removing a tumor growing around essential nerves.

After the tests for the Diagnosis of brain tumor are done, the doctor will analyze all the results with you. If the diagnosis is cancer, these results can help the doctor to describe cancer.


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