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Magnetoencephalography (MEG)

How does Magnetoencephalography work?

MEG uses a sensitive machine to detect tiny magnetic fields produced by brain cells (neurons) as they talk to each other. This can be more sensitive than electroencephalography (EEG) and provide better information about where seizures start. More sensitivity allows MEG to detect brain activity with great precision. This is crucial for planning surgeries and understanding complex brain functions.

How to prepare for Magnetoencephalography?

Patients should avoid wearing any metal objects. These can interfere with the magnetic signals. Comfortable, metal-free clothing is recommended. Patients might also need to wash their hair the night before to make sure no hair products or makeup are present. Hair products could affect the results.

The night before the test your doctor may ask that you sleep less so you are more likely to fall asleep. Sleeping during the MEG will help you to keep your head still and also allow more abnormalities to be recorded.

On the scan day, you may need to complete some paperwork before the procedure. Parents of young children should bring a favorite toy or book to help keep their child calm and comfortable. The child should have a light meal before the test, as the scan can take some time.

What to expect from Magnetoencephalography?

During an MEG exam, patients sit or lie down. A large, helmet-shaped device goes around the patient's head without touching it. MEG is comfortable, quiet and doesn't use radiation. The length of the scan can vary, but it usually takes about one to two hours. Patients need to stay still during the scan so that the results will be accurate. No seizures need to occur during the test. If the child can't remain still during the exam, doctors might use sedation or anesthesia, shorten the scan, or let a parent stay with them. Your doctor will talk with you about the best option for your child. After the scan, no recovery time is needed unless sedation is used. Patients can do their normal activities.

How is Magnetoencephalography different from fMRI?

MEG and fMRI are brain imaging tools, but they look at brain activity in different ways. Functional magnetic resonance imaging (fMRI) measures blood flow, showing which brain parts are involved in tasks but not the exact timing. MEG directly measures magnetic fields, offering precise timing of brain activity. This is crucial for studying rapid brain events like seizures.

How is Magnetoencephalography different from EEG?

EEG and MEG are similar but measure different signals. An electroencephalogram (EEG) detects electrical activity, while MEG measures magnetic fields. MEG can be more sensitive and cover more brain areas. MEG helps doctors understand where to place electrodes during EEG testing, crucial for planning treatments. During your test, an EEG and MEG will be recorded.