Have you ever heard of this test called `(Magnetoencephalography)` or `(MEG)`? Maybe you or someone you know has been told to do this by a doctor. Don't be afraid, this is actually a very advanced test method, and it doesn't harm our body in any way. Today, we will talk about this `(MEG)` test in a simple way that you can understand.
What is MEG? It's very simple!
Simply put, `(MEG)` is a test that measures the magnetic fields generated by electrical currents in your brain. Imagine, it's like tiny electrical messages are being exchanged inside our brains . This electricity creates a magnetic field. Those magnetic fields are what this `(MEG)` machine measures.
This allows doctors to see your brain activity like a map. This is especially helpful in conditions like epilepsy , where they can pinpoint exactly where in the brain seizures are coming from.
The most important thing is that this test does not harm the body (`noninvasive`). That means you do not need to insert needles or do surgery. You are not exposed to radiation like `(X-rays)`. Among the current methods, this `(MEG)` is the most advanced way to record and analyze brain activity.
What are the uses of MEG testing?
Neurologists and neurosurgeons use this (MEG) test for two main reasons:
1. Assess your brain's spontaneous activity. This can help pinpoint the exact location of seizures in someone with epilepsy. This is very important for planning epilepsy surgery. Imagine Samantha has epilepsy and needs surgery. Then the doctors do an MEG to see which part of the brain the seizures are coming from, and target that part only and do the surgery.
2. Test how your brain responds to external stimuli. This can accurately map the areas of the brain involved in things like movement, sensation, language, and vision. This is very useful for planning surgeries for people with brain tumors.
In addition, MEG is also a very important part of neurological and psychiatric research, where scientists are conducting research to gain a deeper understanding of the functioning of the human brain.
How does the MEG test work? A little scientific, but simple!
The nerve cells in our brains communicate with each other by generating small electrical voltages. When these electrical currents flow, they create a magnetic field. Those magnetic fields are detected, recorded, and analyzed by sensitive magnetic sensors in the MEG machine.
But, this magnetic field generated by your brain is very, very weak. Therefore, special sensor systems are needed to capture that signal. These systems consist of small, high-resolution coils. These are connected to devices called SQUIDs – superconducting quantum interference devices. There are more than 300 of these sensors inside a helmet-like device that you wear during the test.
While you're lying still, sometimes listening to sounds, or doing something like looking at pictures, the sensors in this helmet, along with specialized computer software, work together to detect and record the activity of nerve cells. MEG records normal and abnormal signals in the brain every millisecond . These magnetic fields are then displayed on a computer screen along with an anatomical image of your brain. This allows you to "map out" where certain brain activities start and when they occur.
How do you prepare for an MEG test?
If you are having a MEG test, your doctor will tell you if you need to stop eating or drinking before the test. He/she will also tell you if you need to make any changes to your medications or your daily routine.
- Do not wear makeup or hair products on the day of the test. They may interfere with the test.
- Also, you cannot bring any metal objects into the examination room. For example, jewelry, glasses, hairpins, underwire bras, and clothing with metal accessories. If necessary, you will be given a medical gown to wear.
Important: If you have any medical devices implanted inside or outside your body, you must inform your doctor before the test. If they contain metal, if they have anything that can interfere with magnetic fields, or if they cannot be removed, you may not be able to have this test. Some of these devices include:
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* Artificial heart valves.
* Artificial limbs or metallic prosthetic joints.
* Cardiac defibrillators and pacemakers.
* Certain brain aneurysms.
* Certain metal coils placed within blood vessels.
* Cochlear implants.
* Implanted drug infusion ports.
* Implanted nerve stimulators.
* Metal teeth braces.
* Metal pins, screws, plates, stents or surgical staples.
* Programmable shunts.
What to expect during the MEG test?
Depending on the reason for the `(MEG)` test, there may be slight variations in the test procedure. Typically, this is what happens:
1. You will need to remove all metal objects from your body and wear a medical gown .
2. Babies and young children may need to be given sedation or general anesthesia to help them remain still during the MEG test. If this is the case, a small tube called an IV will be inserted into a vein in the arm to give the medication.
3. To make sure your head is in the correct position relative to the sensors on the helmet, a doctor may temporarily tape three or four small coils (`positioning coils`) to your head in three or four places . Then, they will measure the positions of these coils with a special `wand-like device`.
4. To remove small magnetic signals that may be attached to your body from the environment, a doctor will move a circular device (called a `degausser`) over your body.
5. Then, you will be made to lie down on a movable examination table, or placed in a special chair connected to the `(MEG)` machine.
6. The doctor will put the helmet with the `(MEG)` sensors on your head. When you put on this helmet, you will feel very little `claustrophobia`. The most important thing is that you put your head inside the helmet so that your brain is as close as possible to the sensors of the `(MEG)` machine.
7. Depending on the reason for the test, you may be asked to lie still or lie down . It is very important to try to keep your head still during the test.
8. To map the sensory areas of your brain, the test asks you to do certain tasks. For example, reading words on a screen, answering questions, or repeatedly pressing a button.
9. Sometimes, a doctor may give you a small electric current to measure how your brain responds to it. It will make you feel like you're being tickled, but it won't hurt.
10. Once the doctor has all the information they need, the examination is complete. A specialist then analyzes the reports.
During the test, you will not feel any sensation from the MEG machine or feel any pain. There is a two-way intercom system and a video monitoring system in the room, so you can talk to the person doing the test at any time, and they can talk to you.
Some doctors may also perform an EEG (electroencephalogram) or MRI (magnetic resonance imaging) scan along with the MEG test. In that case, additional steps may be added to the procedure.
The ``(MEG)`` test usually takes about an hour or two to complete.
What happens after the MEG test?
If you or your child were given sedation or anesthesia for the test , a doctor will monitor you for 30 minutes to two hours after the test to make sure you are recovering well. Someone will need to drive you home.
Unless you are given sedatives, there is no special recovery time required. You can resume your normal activities.
Are there any risks to an MEG test?
This is the best news! There is no risk currently identified in the `(MEG)` test. So there is no reason to be afraid.
How long does it take to know the results of the MEG test?
It can take specialists several days, sometimes weeks, to review the results of an MEG test. This is because doctors use MEG tests to plan complex brain surgeries, which can involve several specialists working together.
Once they have developed a plan, your medical team will discuss the results with you and discuss what to do next.
What is the difference between MEG and MRI?
Although both of these are brain tests, there is a slight difference.
- An MRI (magnetic resonance imaging) of the brain uses a large magnet and a computer to create images of your brain by collecting structural information. That is, what the brain looks like and how the parts are arranged.
- MEG involves recording the magnetic fields from the nerve cells (neurons) in your brain using hundreds of special sensors and a computer. These fields appear as brain waves.
Doctors often combine MRI and MEG to perform a procedure called Magnetic Source Imaging (MSI) . MSI can create functional maps of brain activity.
MEG is also different from functional MRI (fMRI). fMRI looks at changes in blood flow in certain areas of your brain when you do certain tasks. Both MEG and fMRI look at brain activity, but MEG shows more specific areas of activity. fMRI shows general areas. In addition, MEG is better at showing how brain activity changes over time (temporal characteristics).
What is the difference between MEG and EEG?
The first difference between these two diagnostic tests is:
- An EEG (electroencephalography) records the electrical activity of your brain.
- MEG records the magnetic fields in your brain (which are caused by electrical activity).
Another difference is that MEG is much more sensitive and accurate at recording brain activity than EEG. Your skull and cerebrospinal fluid (CSF) can distort the electrical activity recorded by an EEG. However, these tissues do not distort the magnetic fields. This gives MEG a better “image” of your brain, or spatial resolution . That is, it can pinpoint areas of abnormal activity.
Sometimes doctors do an EEG along with the MEG to gather more information about where the brain activity is coming from.
An important message for you.
As you can see, this test, called Magnetoencephalography (MEG), is a very useful, harmless, and safe test that helps doctors map sensitive areas of your brain and pinpoint the exact location of things like seizures.
If you have a ``(MEG)`` test and you have any concerns or doubts about it, be sure to ask your doctor. They are there to answer your questions and support you. Don't be afraid of anything!
` MEG, Magnetoencephalography, brain tests, epilepsy, seizures, brain surgery, neurology
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