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Specialty Imaging
Magnetoencephalography (MEG)
The brain regulates the function of many organs and is at the center of our speech, movement, memory and thoughts. Brain diseases such as epilepsy or a tumor can greatly affect the way the brain functions and the quality of a person’s life. These diseases can also be life-threatening.
For certain people with epilepsy or a brain tumor, surgery may be a treatment option. For epilepsy, surgery is done to remove the area(s) of brain tissue causing seizures. For people with a brain tumor, the goal of surgery is to remove as much of the tumor as possible.
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The Magnetoencephalography (MEG) machine. | One of the great challenges of brain surgery is removing the diseased part of the brain, while sparing healthy brain tissue that controls vital functions. Before surgery can be done in the brain, it’s crucial to distinguish the “bad” tissue from the “good” tissue. This is done through a process called “brain mapping.” This mapping of abnormal and normal areas in the brain is performed using a variety of techniques. However, the most relied-upon techniques for brain mapping require neurosurgical procedures.
In epilepsy, accurate determination of the areas from which seizures arise is performed with electrical recordings directly from the surface of the brain. The electrodes are implanted on the brain’s surface. These same electrodes can also be used to electrically map functional areas such as language, motor functions or vision. Electrical mapping of the brain can also be done during neurosurgical procedures for removing tumors after exposure of the brain surface.
The relationship between abnormal areas that need to be targeted for surgery and surrounding functional tissue, and the feasibility of successful surgery, is only clear after the patient has undergone an invasive test that involves major surgery.
A non-invasive test that provides much of the same information can be extremely valuable for providing a better assessment of the risks and benefits of surgical treatment, without an invasive test that often involves several days of hospitalization and substantial surgical risks.
Mapping the Brain with MEG
Magnetoencephalography (MEG) is a non-invasive diagnostic tool that can help neurologists and neurosurgeons evaluate and map brain activity before surgery. MEG offers a way to localize brain activity with a high spatial and temporal resolution, and represents a significant advance in the care of patients with brain tumors or severe epilepsy. A MEG scan is performed as an outpatient procedure. For some patients, MEG can replace invasive testing done in the ICU or in the operating room.
Froedtert & The Medical College of Wisconsin are the first in Wisconsin to offer MEG in a clinical (patient care) setting. In addition to clinical uses for neurosurgical planning, Froedtert & The Medical College will also be conducting research studies using MEG to further develop this technology. Children receiving care for a brain tumor or epilepsy at Children’s Hospital of Wisconsin will also benefit from the availability of MEG for surgical planning. |
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This illustrates how MEG, a non-invasive diagnostic tool, brings anatomical and physiological data together to yield images of brain physiology registered to the patient's brain structures. The structural/anatomical information is provided by high-resolution MRI. The sources of the recorded MEG signals are computed based on patient-specific anatomy and projected back onto the MRI.
The MEG scanner was purchased through the generous gift of an anonymous donor. To find out how your financial support can help with similar advances in health care, visit the Froedtert Hospital Foundation. |
Sylvain Baillet, PhD, is Associate Professor of Neurology and scientific director of the MEG Program at Froedtert & The Medical College of Wisconsin. Dr. Baillet's expertise concerns the analysis of anatomical and functional brain signals as revealed by non-invasive brain imaging techniques. His background includes basic research with MEG in combination with MRI to develop techniques to obtain images of electrical activity of the brain. In the MEG Program, he conducts both clinical investigations with MEG and basic brain imaging research.
Author: Marla Fraunfelder | Medical Reviewer: | Sylvain Baillet, PhD |
Last Review Date: Nov. 4, 2008 |
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