Magnetoencephalography, abbreviated as MEG, is the latest technology to directly detect neurological activity in the brain through the measurement of extremely weak biomagnetic signals emitted by neural currents in the brain. Since the MEG process does not release any harmful rays, energy or machine noise, nor does it require the injection of any contrast or imaging agent, it is a completely non-invasive and non-damaging technique for detecting brain function. It can be widely used for the development of brain function research and the early diagnosis of clinical brain diseases. Magnetoencephalography has enabled mankind to study the complex functions of the brain and to treat brain diseases in an unprecedented way.
Elekta Neuromag MEG is the most advanced in the world. It obtains neurophysiological information of the whole head through up to 306 magnetoencephalography channels, and then converts it into a magnetic brain profile and isomagnetogram through comprehensive computer image information processing, and then gets the signal source localization by fitting the corresponding mathematical model. Finally, it is integrated with MRI, CT and other anatomical imaging information to form magnetic source imaging (MSI) for brain anatomical localization, which can accurately reflect the transient changes of brain function at ms/mm level, including the study of higher brain functions such as thinking and emotion.
Compared with existing CT, MRI, PET, SPECT, EEG and other brain anatomy or function testing devices, magnetoencephalography has the following advantages:
1, the magnetic field is not affected by the soft tissue of the scalp, skull and other structures, and does not produce signal attenuation like EEG. Therefore, the full-head 306-channel MEG has a spatial resolution accurate to the millimeter.
2, MEG directly measures the electrophysiological activity of the brain and can record neurophysiological changes in real time at the millisecond level, so MEG has a better temporal resolution than current imaging examinations.
3. It does not release any harmful rays, energy or machine noise, nor does it require any injection of contrast or imaging agent, which is non-invasive to human body and easy to detect.
Magnetoencephalography can be applied to the following areas.
1.Epilepsy
Epilepsy is an area where magnetoencephalography is more widely used clinically, mainly for detecting the source of epileptogenesis, especially for preoperative localization of refractory epilepsy.
Studies have shown that only about 20% of patients undergoing epilepsy surgery can be diagnosed by imaging data alone, while the rest require localization of epileptic foci by functional brain images. Previously, scalp EEG tracings were used to localize only 30% to 40% of patients, and the electrical signal was often attenuated or even lost due to the high resistivity of the skull and scalp, making the test results less reliable and not providing sufficient localization and functional information for treatment. For many patients with refractory epilepsy requiring surgical focal resection of the epileptogenic focus, magnetoencephalography can provide accurate localization. mEG can detect electrical activity of epileptic foci several millimeters in diameter in the cortex with a resolution time phase of up to 1 ms, facilitating differentiation between the epileptic focus and its mirror image source. The foci are destroyed during surgery and the mirror source disappears. In addition, some seizure initiation areas can be far away from the foci of imaging changes, and the treatment of epilepsy is often ineffective by simply removing these foci, while MEG can locate the seizure initiation areas and provide a localization basis for the treatment of such patients with epilepsy.
2. Localization of important functional areas around brain tumors
The functional areas of the brain vary among individuals, and when there is a brain tumor, the tumor also causes extrusion and displacement of the surrounding normal functional areas. Magnetoencephalography can show the three-dimensional relationship between tumor and functional areas of brain, so that brain surgeons can avoid damaging important functional areas while removing tumor to the largest extent, thus improving the quality of life of patients after surgery. For certain patients who are not suitable for surgery, magnetoencephalography can also guide the localization of gamma knife treatment. Currently, the main functional areas are: somatosensory cortex, motor cortex, auditory cortex, visual cortex and language cortex localization.
3.Brain function examination
Magnetoencephalography can detect areas of brain function damage that cannot be detected by imaging such as magnetic resonance or electroencephalography. For example, some mild traumatic brain injury, super early cerebral infarction and early Alzheimer’s disease. These patients have mild or absent clinical symptoms, normal CT and MRI or EEG examinations, and magnetoencephalography can provide objective evidence to determine the extent of brain damage. Thus, the following objectives can be achieved.
3.1 Assessment of the extent and degree of functional damage to brain tissue in stroke patients.
3.2 To observe the changes in local damage to the neural network of the brain by functional rehabilitation after stroke and to provide a new assessment tool for the efficacy of rehabilitation of stroke patients.
3.3 Confirmation of the extent and degree of brain damage after mild traumatic brain injury.
3.4 Early diagnosis of Alzheimer’s disease (dementia) and a range of dementia types to enable early treatment and slow progression.
4. Diagnosis of neuropsychiatric diseases
With the in-depth development of MEG in neuroscience research, MEG will become an important tool for studying the special functions of human brain and understanding neuropsychiatric diseases. MEG can assist in the further diagnosis and classification of these neuropsychiatric diseases, help to deepen the understanding of neuropsychiatric diseases and the evaluation of treatment effects, help to realize individualized treatment, and help to improve the efficacy of treatment.
The non-invasive nature of MEG also allows it to be applied in pediatric neurology, and its potential application in childhood brain development disorders is particularly valued. It is particularly suitable for the early diagnosis and differential diagnosis of pediatric neuropsychiatric disorders, such as audiovisual dysfunction, learning disabilities, dyslexia, attention disorders, mental retardation, autism, etc., facilitating early prevention and achieving early treatment and long-term improvement of symptoms in these disorders.
In conclusion, magnetoencephalography is a non-invasive and sensitive means of detecting brain function. Combined with EEG, MRI and other techniques, it will give us a more comprehensive understanding of brain functions and diseases.