Multi-channel atomic magnetometer for magnetoencephalography: A configuration study

Kim, Ki Woong; Beguš, Samo; Xia, Hui; Lee, Seung‐Kyun; Jazbinsek, V.; Trontelj, Z.; Romalis, Michael

doi:10.1016/j.neuroimage.2013.10.040

Cited by 130 publications

(54 citation statements)

References 19 publications

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“…In addition, the detection of epileptiform activity in rodents using micro-fabricated OPM sensors [43] has been shown. These empirical demonstrations, coupled with miniaturization of OPM cells to the millimetre scale [44] and the introduction of the first multi-channel measurements [45, 46] have begun to suggest that OPM technology could transform the utility of MEG with chip-scale sensors, in principle, facilitating the use of several hundred detectors, located just millimetres from the scalp surface, with a completely flexible geometry.…”

Section: Introductionmentioning

confidence: 99%

On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study

et al. 2016

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Magnetoencephalography (MEG) is a sophisticated tool which yields rich information on the spatial, spectral and temporal signatures of human brain function. Despite unique potential, MEG is limited by a low signal-to-noise ratio (SNR) which is caused by both the inherently small magnetic fields generated by the brain, and the scalp-to-sensor distance. The latter is limited in current systems due to a requirement for pickup coils to be cryogenically cooled. Recent work suggests that optically-pumped magnetometers (OPMs) might be a viable alternative to superconducting detectors for MEG measurement. They have the advantage that sensors can be brought to within ~4 mm of the scalp, thus offering increased sensitivity. Here, using simulations, we quantify the advantages of hypothetical OPM systems in terms of sensitivity, reconstruction accuracy and spatial resolution. Our results show that a multi-channel whole-head OPM system offers (on average) a fivefold improvement in sensitivity for an adult brain, as well as clear improvements in reconstruction accuracy and spatial resolution. However, we also show that such improvements depend critically on accurate forward models; indeed, the reconstruction accuracy of our simulated OPM system only outperformed that of a simulated superconducting system in cases where forward field error was less than 5%. Overall, our results imply that the realisation of a viable whole-head multi-channel OPM system could generate a step change in the utility of MEG as a means to assess brain electrophysiological activity in health and disease. However in practice, this will require both improved hardware and modelling algorithms.

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Section: Introductionmentioning

confidence: 99%

On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study

et al. 2016

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“…Gradiometers measure the gradient of the magnetic field, which leads to an amplitude reduction of the signal from distant, i.e., deep sources. Our results will be compared to those of published work on in vitro data [19,24,29] and phantom data [2,4,10,16,30], and are relevant to emerging new MEG devices based on atomic magnetometers [18,33].…”

Section: Introductionmentioning

confidence: 97%

Magnetoencephalographic accuracy profiles for the detection of auditory pathway sources

Bauer

Trahms

Sander

2015

Biomedical Engineering / Biomedizinische Technik

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The detection limits for cortical and brain stem sources associated with the auditory pathway are examined in order to analyse brain responses at the limits of the audible frequency range. The results obtained from this study are also relevant to other issues of auditory brain research. A complementary approach consisting of recordings of magnetoencephalographic (MEG) data and simulations of magnetic field distributions is presented in this work. A biomagnetic phantom consisting of a spherical volume filled with a saline solution and four current dipoles is built. The magnetic fields outside of the phantom generated by the current dipoles are then measured for a range of applied electric dipole moments with a planar multichannel SQUID magnetometer device and a helmet MEG gradiometer device. The inclusion of a magnetometer system is expected to be more sensitive to brain stem sources compared with a gradiometer system. The same electrical and geometrical configuration is simulated in a forward calculation. From both the measured and the simulated data, the dipole positions are estimated using an inverse calculation. Results are obtained for the reconstruction accuracy as a function of applied electric dipole moment and depth of the current dipole. We found that both systems can localize cortical and subcortical sources at physiological dipole strength even for brain stem sources. Further, we found that a planar magnetometer system is more suitable if the position of the brain source can be restricted in a limited region of the brain. If this is not the case, a helmet-shaped sensor system offers more accurate source estimation.

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“…Superconducting quantum interference devices (SQUIDs) have been traditionally used in sensitive applications at low frequency, for example, in magneto-encephalography (MEG), but they require a cryogenic infrastructure. Atomic magnetometers (AMs) operating in the spin-exchange-relaxation-free (SERF) regime have demonstrated similar sensitivity to SQUIDs [1,2] and are a promising cryogen-free alternative to SQUIDs for many applications, such as MEG [3,4,5,6,7], magneto-cardiography (MCG) [8,9], ultra-low-field NMR [10,11,12], and MRI [13,14]. …”

Section: Introductionmentioning

confidence: 99%

A High-Sensitivity Tunable Two-Beam Fiber-Coupled High-Density Magnetometer with Laser Heating

Savukov

Boshier

2016

Sensors

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Atomic magnetometers (AM) are finding many applications in biomagnetism, national security, industry, and science. Fiber-coupled (FC) designs promise to make them compact and flexible for operation. Most FC designs are based on a single-beam configuration or electrical heating. Here, we demonstrate a two-beam FC AM with laser heating that has 5 fT/Hz1/2 sensitivity at low frequency (50 Hz), which is higher than that of other fiber-coupled magnetometers and can be improved to the sub-femtotesla level. This magnetometer is widely tunable from DC to very high frequencies (as high as 100 MHz; the only issue might be the application of a suitable uniform and stable bias field) with a sensitivity under 10 fT/Hz1/2 and can be used for magneto-encephalography (MEG), magneto-cardiography (MCG), underground communication, ultra-low MRI/NMR, NQR detection, and other applications.

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Multi-channel atomic magnetometer for magnetoencephalography: A configuration study

Cited by 130 publications

References 19 publications

On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study

On the Potential of a New Generation of Magnetometers for MEG: A Beamformer Simulation Study

Magnetoencephalographic accuracy profiles for the detection of auditory pathway sources

A High-Sensitivity Tunable Two-Beam Fiber-Coupled High-Density Magnetometer with Laser Heating

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