TREATMENT OF A BRAIN TUMOR

1. How is a brain tumor diagnosed?
A brain tumor diagnosis usually involves several steps and can sometimes include a neurological examination, brain scan(s), and/or a biopsy.
A neurological examination is a series of tests to measure the function of the patient’s nervous system and physical and mental alertness. If responses to the exam are not normal, the doctor may order a brain scan or refer the patient to a neurologist or neurosurgeon, who will then order a brain scan.
A brain scan is a picture of the internal structures in the brain. A specialized machine takes a scan in much the same way a digital camera takes a photograph. Using computer technology, a scan compiles an image of the brain by photographing it from various angles.
Some types of scans use a contrast agent (or contrast dye), which helps the doctor see the difference between normal and abnormal brain tissue. The contrast agent is injected into a vein and flows into brain tissue. Abnormal or diseased brain tissue absorbs more dye than normal healthy tissue. The most common scans used for diagnosis are as follows:
MRI (Magnetic Resonance Imaging) is a scanning device that uses magnetic fields and computers to capture images of the brain on film. It does not use x-rays. It provides pictures from various planes, which permit doctors to create a three-dimensional image of the tumor. The MRI detects signals emitted from normal and abnormal tissue, providing clear images of most tumors.
CT or CAT Scan (Computed Tomography) combines sophisticated x-ray and computer technology. CT can show a combination of soft tissue, bone, and blood vessels. CT images can determine some types of tumors, as well as help detect swelling, bleeding, and bone and tissue calcification. Usually, iodine is the contrast agent used during a CT scan.
PET Scan (Positron Emission Tomography) provides a picture of the brain’s activity, rather than its structure, by measuring the rate at which a tumor absorbs glucose (a sugar). The patient is injected with deoxyglucose that has been labeled with radioactive markers. The PET scan measures the brain’s activity and sends this information to a computer, which creates a live image. Doctors use PET scans to see the difference between scar tissue, recurring tumor cells, and necrosis (cells destroyed by radiation treatment).

1. What else should I know about diagnostic tests?
Because an MRI uses magnetic fields, people who have metal implanted in their body in any form should let the doctor know about it before scheduling the procedure. An MRI may not be an option for these patients because the intense magnetic fields can damage some types of implanted medical devices. Patients should advise the doctor if they have a pacemaker, cardiac monitor, surgical clip, or facial tattoos.
In a standard MRI scan, the patient lies on a narrow table, which slides through a long, cylindrical tube with a narrow opening. Although there is enough room for the patient’s body inside the cylinder, the patient will not be able to move around. The scan takes approximately 15-45 minutes. During the scan, the patient will hear loud banging sounds, caused by the electronics within the machine. Patients may request earplugs to reduce noise. Some people find the MRI claustrophobic and ask for a sedative beforehand to relax. Other people request an open MRI.
An open MRI machine does not have a cylinder, so the patient is not enclosed. The procedure lasts approximately 45 minutes. There is some discussion among doctors concerning the quality of the images of an open MRI compared to the standard or closed MRI.
Contrast agents may cause allergic reactions in some patients. Gadolinium, the contrast agent used with an MRI, may cause temporary headaches but has no other known side effects. Iodine is the contrast agent most commonly used for CT scanning. If you know you are allergic to iodine, tell your doctor. Allergic reactions can include rashes, a warm sensation, or, in rare cases, difficulty breathing.
CT scans involve exposure to ionizing radiation, which is known to cause cancer. This is a concern for people who may need multiple CT scans and for children, because they are more sensitive to radiation than adults. It is wise for people who have had frequent x-ray exams and parents of children who have brain tumors to keep a record of their x-ray history. This information can help doctors make informed decisions and minimize radiation over-exposure.

A biopsy is a surgical procedure in which a sample of tissue is taken from the tumor site and examined under a microscope. The biopsy will provide information on types of abnormal cells present in the tumor. The purpose of a biopsy is to discover the type and grade of a tumor. A biopsy is the most accurate method of obtaining a diagnosis.
An open biopsy is done during a craniotomy. A craniotomy involves removing a piece of the skull in order to get access to the brain. After the tumor is resected (completely removed) or debulked (partially removed), the bone is usually put back into place. A closed biopsy (also called a stereotactic or needle biopsy) may be performed when the tumor is in an area of the brain that is difficult to reach. In a closed biopsy, the neurosurgeon drills a small hole into the skull and passes a narrow hollow needle into the tumor to remove a sample of tissue.
Once a sample is obtained, a pathologist examines the tissue under a microscope and writes a pathology report containing an analysis of the brain tissue. Sometimes the pathologist may not be able to make an exact diagnosis. This may be because more than one grade of tumor cells exists within the same tumor. In some cases, the tissue may be sent to another institution for additional analysis.