OPM-MEG
Optically Pumped Magnetometer Magnetoencephalography
In the last few decades, a new type of instrument for detecting magnetic fields has been developed, namely the Optical PumpingAtomic Magnetometer (OPM). Its core is a small cell filled with alkali metal gas. Alkali-metal atoms are polarized by a circularly polarized pump light, and then the linearly polarized light is used to detect the dynamics of the polarized spin under a magnetic field. Currently, the atomic magnetometer can achieve an accuracy of 6 fT, with a small probe size which is only 10 mm3. It could replace SQUID as the core device of the MEG. Further, the atomic magnetometer is expected to simultaneously measure the three-dimensional magnetic field vector information by means of suitable measurements, which is much stronger than the capability of the existing SQUID. It is expected to enable the brain magnetometer to obtain higher spatial resolution and source localization accuracy. Most importantly, SQUID-MEG is cooled by liquid helium, while OPM-MEG works at room temperature and only requires low-power heating (heating of the steam chamber) in a small area. Thus the cost of procurement and operation decrease and the widespread use of MEG facilitates.
Less environmental requirements
Its smaller size and lower cost allow it to be used in smaller magnetically shielded environments such as a shielded bucket, facilitating widespread application.
Lower cost of use
Operated at room temperature and no liquid helium or other consumables are required, making its cost of use almost zero when compared to the millions of dollars of liquid helium consumed annually by conventional MEG.
Higher Sensitivity
Closer to the scalp surface, a higher signal-to-noise ratio for detecting neural electrical activity, and ultra-high sensitivity of 7-10 fT/√Hz (10-15 T).
Broader applicability
It is flexible and wearable, for infants to adults, and allows for movement.
brain Magnetic signal acquisition and analysis software system
Independently developed on the Windows platform, it utilizes a state-of-the-art, multi-channel, wireless, and wired combined software acquisition system. All data recording operations are performed using the latest graphical user interface, eliminating the need for coding. The operation process is simple, and the functionality is stable. It is equipped with complementary modules such as Synthetic Aperture Magnetometer (SAM), Multi-Frequency Source Imaging (MFSI), dipoles, spectra, topography, etc. It also provides medical 3D image processing tools such as registration, segmentation, and grid division.
During data acquisition, the software could dynamically detect the MEG signal and adjust various display parameters at any time, knowing exactly the MEG signal and the noise artifacts.The brain MEG data analysis software supports state-of-the-art data analysis methods, including those used for data input/output, preprocessing, and data management.
The software has powerful visualization and analysis capabilities, such as source reconstruction using spatial filtering, distributed source and beamformers, and non-parametric statistical testing.Additional data like clinical EEG, MRI, etc. can easily be added and it could automatically match the spatial locations of various data using datum points.
More Bio-Magnetic Applications
DBS（Deep Brain Stimulation）, commonly known as "brain pacemaker", Its application in the field of neurological and psychiatric diseases has been explored in more than ten diseases. Currently, the FDA has approved DBS for three indications, namely Parkinson's disease, dystonia, and primary tremor.
As a surgical tool, DBS can directly measure pathological brain activity and can provide modifiable stimulation to treat neurological and psychiatric disorders associated with abnormal circuit function. DBS is a neurosurgical procedure involving the implantation of electrodes at specific locations within the brain, and it can provide a constant or intermittent current from the implanted battery power source. More than 160,000 patients worldwide have undergone DBS for various neurological and non-neurological disorders, and this number is increasing every year. As a scientific tool, DBS can be used to study the physiological basis of brain dysfunction, enabling the identification and correction of pathological neuronal signals, helping to drive technological innovation, and improving safety and clinical outcomes.
Current preoperative localization and intraoperative examination of DBS still relies on MRI and CT, and there is a lack of means to detect nerve activity signals in real time. OPM-MEG, as a non-invasive and radiation-free brain examination tool, provides a more accurate, safer and more reliable new diagnostic method for DBS surgery from preoperative functional area localization, intraoperative target function localization, and postoperative in vivo electrode examination and regulation needs.
With the continuous exploration and development of brain science by MEG technology, the indications of DBS are expected to be extended to epilepsy, Alzheimer's disease, anorexia nervosa, major depression, bipolar disorder, obsessive-compulsive disorder, Tourette's syndrome and other refractory brain diseases in the future.
Similar to the MEG, the OPM light pump magnetometer can also be used for cardiac magnetic signal detection,namely Magnetocardiogram (MCG).It is the most promising tool in diagnostic VCD because of the advantages of being completely non-invasive, non-radiation, non-contact, high sensitivity.
Compared with conventional CVD diagnostic tools (ECG, echocardiography), MCG has higher sensitivity and signal-to-noise ratio and is sensitive to tangential currents. Since the ECG is a graphical record of the electrical activity of the heart for each cardiac cycle from the body surface, it cannot detect the tangential currents of the heart activity, especially eddy currents. While MCG can not only detect the tangential currents, but also the currents over the whole heart into two-dimensional and three-dimensional images, and the location of the lesion can be localized according to the inversion algorithm of the heart model.
MEG also plays an irreplaceable role in cardiology examinations where traditional invasive or active diagnostic tools cannot reach, e.g. MCG does not cause any negative effects on the unborn fetus that are associated with active medical examinations. However, it is not advisable to perform active 4D color ultrasonography on the fetal heart until 12 weeks of gestation and not advisable to perform active medical examinations until 16 weeks of gestation. Therefore, MCG can be conducted at the first signs of fetal heart formation, regardless of the time of pregnancy.
Currently, diagnostic structural imaging techniques (e.g., magnetic resonance imaging of the spine, X-ray computed tomography imaging, etc.) are commonly used to assist physicians in the diagnosis of degenerative structural lesions of the spinal cord (e.g., spinal cervical spondylosis). However, most of the etiology of all types of spinal disorders comes from damage to the spinal nerves. As the cause of spinal cord lesions always varies from person to person, and the spinal cord itself is narrow and slender, even though some lesions are not visible as distinct features on structural images, the nerves in them have been damaged.
To better assist physicians in diagnosing spinal cord disease, the detection of clear nerve signals becomes a critical problem to be solved. Although the evoked magnetic field of the spine is very weak, only one-tenth of the MEG of the brain, and the nerves of the spinal cord are more difficult to distinguish than those of the brain and heartHowever,Magnetospinography (MSG), as a non-invasive, real-time, high-resolution detection method, remains one of the cutting-edge and urgently needed research projects in clinical settings, especially with the increasing prevalence of spinal diseases today.
