Precision magnetic field modelling and control for wearable magnetoencephalography.
Precision magnetic field modelling and control for wearable magnetoencephalography.
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DOI：
10.1016/j.neuroimage.2021.118401
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发表时间：
2021-11-01
期刊：
影响因子：
5.7
通讯作者：
Brookes, Matthew J.
中科院分区：
文献类型：
--
作者：
Rea, Molly;Holmes, Niall;Hill, Ryan M.;Boto, Elena;Leggett, James;Edwards, Lucy J.;Woolger, David;Dawson, Eliot;Shah, Vishal;Osborne, James;Bowtell, Richard;Brookes, Matthew J.
光泵磁力计（OPM）是一种高灵敏度的紧凑型磁场传感器，为脑磁图（MEG）的低温传感器（超导量子干涉器件-SQUID）提供了一种可行的替代方案。随着可穿戴系统的承诺，提供寿命合规性，在扫描过程中实现移动，并提供更高质量的数据，OPM可以推动MEG仪器的一步变化。然而，只有通过优化的被动磁屏蔽（即将系统封闭在高磁导率材料层中）和电磁线圈的组合来适当控制背景磁场，才能实现这种潜力，以进一步消除剩余磁场。在这项工作中，我们表明，即使在具有极低（<2 nT）剩余磁场的OPM优化被动屏蔽中，头部移动也会在MEG数据中产生明显的伪影，表现为低频干扰。为了对抗这种影响，我们引入了一种磁场映射技术，在该技术中，参与者移动他们的头部使用可穿戴传感器阵列对背景磁场进行采样;将所得数据与模型进行比较，以导出表示被动屏蔽内的三个均匀磁场分量和五个磁场梯度分量的系数。我们表明，这种技术准确地重建已知磁场的大小。此外，通过将获得的系数馈送到双平面电磁线圈系统中，我们能够将阵列所经历的均匀磁场从1.3 ± 0.3 nT的幅度降低到0.29 ± 0.07 nT。最重要的是，我们表明，这个领域的补偿产生一个5倍减少运动伪影在0-2 Hz，在视觉稳态诱发反应实验中使用6 Hz的刺激。我们建议，这种技术可以用于未来的OPM-MEG实验，以提高数据的质量，特别是在试图测量低频振荡的范例，或在鼓励头部运动的实验中。
Optically-pumped magnetometers (OPMs) are highly sensitive, compact magnetic field sensors, which offer a viable alternative to cryogenic sensors (superconducting quantum interference devices – SQUIDs) for magnetoencephalography (MEG). With the promise of a wearable system that offers lifespan compliance, enables movement during scanning, and provides higher quality data, OPMs could drive a step change in MEG instrumentation. However, this potential can only be realised if background magnetic fields are appropriately controlled, via a combination of optimised passive magnetic screening (i.e. enclosing the system in layers of high-permeability materials), and electromagnetic coils to further null the remnant magnetic field. In this work, we show that even in an OPM-optimised passive shield with extremely low (<2 nT) remnant magnetic field, head movement generates significant artefacts in MEG data that manifest as low-frequency interference. To counter this effect we introduce a magnetic field mapping technique, in which the participant moves their head to sample the background magnetic field using a wearable sensor array; resulting data are compared to a model to derive coefficients representing three uniform magnetic field components and five magnetic field gradient components inside the passive shield. We show that this technique accurately reconstructs the magnitude of known magnetic fields. Moreover, by feeding the obtained coefficients into a bi-planar electromagnetic coil system, we were able to reduce the uniform magnetic field experienced by the array from a magnitude of 1.3 ± 0.3 nT to 0.29 ± 0.07 nT. Most importantly, we show that this field compensation generates a five-fold reduction in motion artefact at 0–2 Hz, in a visual steady-state evoked response experiment using 6 Hz stimulation. We suggest that this technique could be used in future OPM-MEG experiments to improve the quality of data, especially in paradigms seeking to measure low-frequency oscillations, or in experiments where head movement is encouraged.
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在头皮安装的磁刻摄影术中用于无效背景磁场的双平面线圈系统。
影响因子：
5.7
作者：
Holmes N;Leggett J;Boto E;Roberts G;Hill RM;Tierney TM;Shah V;Barnes GR;Brookes MJ;Bowtell R
通讯作者：
Bowtell R
影响因子：
3.7
作者：
Boto E;Bowtell R;Krüger P;Fromhold TM;Morris PG;Meyer SS;Barnes GR;Brookes MJ
通讯作者：
Brookes MJ
影响因子：
5.7
作者：
Iivanainen J;Stenroos M;Parkkonen L
通讯作者：
Parkkonen L
影响因子：
1.9
作者：
Huang, Ming-Xiong;Swan, Ashley Robb;Lee, Roland R.
通讯作者：
Lee, Roland R.
影响因子：
56.9
作者：
COHEN, D
通讯作者：
COHEN, D