Tuesday, March 27, 2007


Wake Forest Baptist Medical Center is getting a MEG device that scans the brain for activity and can map it on an MRI scan. It is pretty complicated, but essentially it makes a map of the brain that can identify the exact location for surgery. Below is the description from WFBMC.

MEG measures the magnetic fields created by electric currents generated by the brain’s neurons without the aid of injected radioisotopes or even attached electrodes. An array of 260 magnetic sensors surrounds the head, allowing induced brain magnetic potentials to be recorded from the entire head. These magnetic signals are then projected onto the patient’s own MRI scan, making it possible to localize a given function to a precise portion of the brain. MEG is used for the presurgical localization of critical brain regions (such as the location of language or motor function) and to help locate the site where epileptic seizures begin.

Nerve cells directly generate the magnetic signals detected by MEG, as opposed to other functional imaging tests such as positron emission tomography (PET), single photon emission tomography (SPECT) and MRI, which record secondary changes in blood flow or glucose utilization from which nerve cell activity must then be inferred. Therefore, MEG measures changes and activity not detectable by these other tests. Unlike electroencephalography (EEG), MEG is unaffected by intervening tissues such as the scalp and skull, so signals from deeper areas of the brain that are not detectable by EEG can be identified with MEG.

By identifying the precise locations within the brain that are responsible for the senses, language and other vital processes, doctors can ensure preservation of these functions by avoiding these important areas during surgery. The non-invasiveness of MEG permits it to be used for repeated follow-up measurements without adverse effects.

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