From the Departments of Neurology (O.F.), Pediatric Neurology (C.S., F.C.), Nuclear Medicine (S.G.), and Translational Neuroimaging (V.W., X.D.T.), CUB Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium; Laboratory of Translational Neuroimaging and Neuroanatomy (Laboratoire de Neuroimagerie et Neuroanatomie translationnelles) (LNT), ULB Neuroscience Institute, Université Libre de Bruxelles, 808 Lennik St, Brussels, Belgium (O.F., P.C., S.G., V.W., X.D.T.); Department of Pediatric Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium (A.A.); and Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom (N.H., M.B.).
Radiology. 2022 Aug;304(2):429-434. doi: 10.1148/radiol.212453. Epub 2022 May 3.
Background Magnetoencephalography (MEG) is an established method used to detect and localize focal interictal epileptiform discharges (IEDs). Current MEG systems house hundreds of cryogenic sensors in a rigid, one-size-fits-all helmet, which results in several limitations, particularly in children. Purpose To determine if on-scalp MEG based on optically pumped magnetometers (OPMs) alleviates the main limitations of cryogenic MEG. Materials and Methods In this prospective single-center study conducted in a tertiary university teaching hospital, participants underwent cryogenic (102 magnetometers, 204 planar gradiometers) and on-scalp (32 OPMs) MEG. The two modalities for the detection and localization of IEDs were compared. The test was used to compare IED amplitude and signal-to-noise ratio (SNR). Distributed source modeling was performed on OPM-based and cryogenic MEG data. Results Five children (median age, 9.4 years [range, 5-11 years]; four girls) with self-limited idiopathic (n = 3) or refractory (n = 2) focal epilepsy were included. IEDs were identified in all five children with comparable sensor topographies for both MEG devices. IED amplitudes were 2.3 (7.2 of 3.1) to 4.6 (3.2 of 0.7) times higher ( < .001) with on-scalp MEG, and the SNR was 27% (16.7 of 13.2) to 60% (12.8 of 8.0) higher ( value range: .001-.009) with on-scalp MEG in all but one participant ( = .93), whose head movements created pronounced motion artifacts. The neural source of averaged IEDs was located at approximately 5 mm (n = 3) or higher (8.3 mm, n = 1; 15.6 mm, n = 1) between on-scalp and cryogenic MEG. Conclusion Despite the limited number of sensors and scalp coverage, on-scalp magnetoencephalography (MEG) based on optically pumped magnetometers helped detect interictal epileptiform discharges in school-aged children with epilepsy with a higher amplitude, higher signal-to-noise ratio, and similar localization value compared with conventional cryogenic MEG. © RSNA, 2022 See also the editorial by Widjaja in this issue.
背景 脑磁图（MEG）是一种用于检测和定位局灶性间发性癫痫样放电（IED）的成熟方法。目前的 MEG 系统在刚性的、一刀切的头盔中内置了数百个低温传感器，这导致了几个局限性，特别是在儿童中。目的 确定基于光泵磁强计（OPM）的头皮 MEG 是否能缓解低温 MEG 的主要局限性。材料与方法 本研究为前瞻性单中心研究，在一所三级大学教学医院进行，参与者接受了低温（102 个磁强计，204 个平面梯度计）和头皮（32 个 OPM）MEG。比较了两种检测和定位 IED 的方法。使用检验比较了 IED 幅度和信噪比（SNR）。在基于 OPM 和低温 MEG 数据上进行了分布式源建模。结果 纳入 5 名儿童（中位年龄 9.4 岁[范围，5-11 岁]；4 名女孩），患有特发性（n = 3）或难治性（n = 2）局灶性癫痫。5 名儿童均通过两种 MEG 设备以可比较的传感器拓扑图识别出 IED。头皮 MEG 下 IED 幅度高 2.3（7.2 比 3.1）至 4.6（3.2 比 0.7）倍（ <.001），信噪比高 27%（16.7 比 13.2）至 60%（12.8 比 8.0）倍（值范围：.001-.009），但除了一名因头部运动产生明显运动伪影的参与者（ =.93）外，其他参与者均如此。平均 IED 的神经源位于头皮 MEG 与低温 MEG 之间约 5 毫米（n = 3）或更高处（8.3 毫米，n = 1；15.6 毫米，n = 1）。结论 尽管传感器数量有限，头皮覆盖范围有限，但基于光泵磁强计的头皮脑磁图（MEG）有助于检测学龄期癫痫儿童的间发性癫痫样放电，其幅度更高、信噪比更高，与传统低温 MEG 相比，定位值相似。
