Magnetoencephalography, or MEG scan, works by recording brain magnetic fields generated from the electrical signals of neurons communicating with each other in the brain. Unlike electrical fields recorded via EEG, magnetic fields are not altered by intervening brain tissue, bone or fat. MEG offers superior capability to localize where in the brain activity is being generated. This leads to improved localization of seizure onset and localization of essential brain functions, such as speech, motor activity and vision.
MEG records these incredibly small magnetic fields, typically tens to hundreds of femotesla (10-14 – 10-13 T), noninvasively. Compared with a standard clinical MRI magnet strength of 1.5 Tesla, the strength of the signals detected by MEG is 10-14 times smaller, often compared with hearing a pin drop at a rock concert. In 2012, Cook Children’s became one of only seven freestanding children’s hospitals in the country to offer this advanced technology.
During MEG scanning, magnetic signal is digitalized, filtered and superimposed on the MRI of the brain to precisely localize where in the brain abnormal electrical activity is generated (Figure).
Neurologists can then take this information and better plan surgical procedures to remove the area of the brain generating seizures. MEG scanning also has the capability of identifying important areas of brain which include regions responsible for motor movement, sensory areas, and parts of the brain that control speech and vision. This information is vital for planning epilepsy surgery and avoiding postoperative deficits.
Cook Children’s has not kept MEG as a secret to ourselves. Instead, we have partnered with neighboring institutions to utilize this imaging method to research other disorders that impact brain connectivity, including Alzheimer’s and traumatic brain injury.