Brain Tumor Symptoms & Diagnosis

A CT scan produces a series of detailed, two-dimensional images of the brain created by a computer linked to an x-ray machine. The patient lies on a sliding table that's guided into what looks like a small tunnel where the images are taken. A special dye may be injected into a patient's vein to provide better detail. A CT scan is painless and generally takes less than 10 minutes.

MRI is a procedure that uses a magnet, radio waves and a computer to produce detailed pictures of the brain and spinal cord. It is the most important imaging technique for brain tumors.

Northwestern Medicine and the Malnati Brain Tumor Institute offer specialized applications of MRI imaging, including:

• MRI Spectroscopy - MRI spectroscopy combines MR imaging and analysis of the brain's chemistry. This procedure can be used to grade tumors and assist the surgeon in locating the optimal place for a biopsy if a tumor cannot be removed.
• MR Perfusion - MR perfusion assesses the patient's blood flow and can assist in grading tumors and identifying the best place for a biopsy.
• Functional MRI - This type of MRI is used to determine what parts of the brain "light up" when functions such as speech or recognition are engaged, helping to minimize the chance of injury to these areas.
• Diffusion Tensor Imaging - Diffusion tensor imaging provides detailed information about the motor or visual fibers in the brain, again helping to minimize injury when tumors are near these areas.

PET is a procedure in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner makes detailed, computerized pictures of areas inside the body where the glucose was used.

During an angiogram, dye is injected into a patient's bloodstream, which flows into the blood vessels in the brain so they show up in an x-ray. If a tumor is present, the doctor may be able to see it on the x-ray.

The removal of tissue to look for tumor cells is called a biopsy. The sample removed from the biopsy is analyzed by a pathologist, a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues and organs to diagnose disease. A biopsy can show cancer, tissue changes that may lead to cancer and other conditions. This is the only definitive way to diagnose brain cancer.

A cerebral angiogram, also called a cerebral arteriogram, is an x-ray, or series of x-rays, of the head that shows the arteries in the brain. X-rays are taken after a special dye is injected into the main arteries of the patient's head.

Because some specific types of brain tumors can spread to the spinal fluid, other parts of the brain or the spinal cord, your doctor may order a myelogram to look for metastases. In a myelogram, dye is injected into the cerebrospinal fluid (CSF) that surrounds the spinal cord. The dye shows up on x-ray and can outline the spinal cord to help a doctor look for tumors.

Some types of brain tumors cause calcium deposits in the brain or changes in the bones of the skull. With an x-ray, a doctor can check for these changes.

A doctor may remove a sample of cerebrospinal fluid, the fluid that fills the spaces in and around the brain and spinal cord. This procedure is performed with local anesthesia. The doctor uses a long, thin needle to remove fluid from the spinal column. A spinal tap takes about 30 minutes. The patient must lie flat for several hours afterward to keep from getting a headache. A laboratory checks the fluid for cancer cells or other signs of problems.

For tumors that are difficult to classify using a microscope, your doctor may suggest methylation profiling. Every tumor has a unique DNA profile, similar to a fingerprint. Methylation is a chemical process that allows doctors to see a tumor's DNA profile, leading to more accurate tumor diagnoses for patients.