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.
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DOI：
10.1371/journal.pone.0157655
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Brookes MJ
中科院分区：
文献类型：
--
作者：
Boto E;Bowtell R;Krüger P;Fromhold TM;Morris PG;Meyer SS;Barnes GR;Brookes MJ
脑磁图（MEG）是一种复杂的工具，它能提供丰富的人脑功能的空间、频谱和时间特征信息。尽管具有独特的潜力，但MEG受到低信噪比（SNR）的限制，这是由大脑产生的固有小磁场和头皮到传感器的距离引起的。由于需要对拾取线圈进行低温冷却，后者在当前系统中受到限制。最近的工作表明，光泵磁强计（OPMs）可能是一个可行的替代超导探测器的MEG测量。它们的优点是传感器可以带到头皮的~4 mm范围内，从而提供更高的灵敏度。在这里，使用模拟，我们量化的假设OPM系统的灵敏度，重建精度和空间分辨率方面的优势。我们的研究结果表明，多通道全头OPM系统提供（平均）五倍的灵敏度提高成人大脑，以及重建精度和空间分辨率的明显改善。然而，我们也表明，这种改进关键取决于准确的前向模型;事实上，我们的模拟OPM系统的重建精度只优于模拟超导系统的情况下，前向场误差小于5%。总的来说，我们的研究结果意味着，实现一个可行的全头多通道OPM系统可以产生一个阶跃变化的效用MEG作为一种手段，以评估大脑电生理活动的健康和疾病。然而，在实践中，这将需要改进的硬件和建模算法。
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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