Department of Neurology and Clinical Neurophysiology, Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht, The Netherlands.
Hum Brain Mapp. 2013 Sep;34(9):2032-44. doi: 10.1002/hbm.22049. Epub 2012 Mar 19.
Magnetoencephalography (MEG) is used in the presurgical work-up of patients with focal epilepsy. In particular, localization of MEG interictal spikes may guide or replace invasive electroencephalography monitoring that is required in difficult cases. From literature, it is not clear which MEG source localization method performs best in this clinical setting. Therefore, we applied three source localization methods to the same data from a large patient group for which a gold standard, interictal spikes as identified in electrocorticography (ECoG), was available. The methods used were multiple signal classification (MUSIC), Synthetic Aperture Magnetometry kurtosis [SAM(g2)], and standardized low-resolution electromagnetic tomography. MEG and ECoG data from 38 patients with refractory focal epilepsy were obtained. Results of the three source localization methods applied to the interictal MEG data were assigned to predefined anatomical regions. Interictal spikes as identified in ECoG were also assigned to these regions. Identified regions by each MEG method were compared to ECoG. Sensitivity and positive predictive value (PPV) of each MEG method were calculated. All three MEG methods showed a similar overall correlate with ECoG spikes, but the methods differ in which regions they detect. The choice of the inverse model thus has an unexpected influence on the results of magnetic source imaging. Combining inverse methods and seeking consensus can be used to improve specificity at the cost of some sensitivity. Combining MUSIC with SAM(g2) gives the best results (sensitivity = 38% and PPV = 82%).
脑磁图（MEG）用于局灶性癫痫患者的术前评估。特别是，MEG 发作间期棘波的定位可以指导或替代在困难病例中需要的侵入性脑电图监测。从文献中可以看出，在这种临床环境下，哪种 MEG 源定位方法表现最佳尚不清楚。因此，我们将三种源定位方法应用于同一大患者组的数据，这些数据有一个金标准，即皮层脑电图（ECoG）中识别的发作间期棘波。所使用的方法是多信号分类（MUSIC）、合成孔径磁强计峰度 [SAM(g2)] 和标准化低分辨率电磁层析成像。从 38 例耐药性局灶性癫痫患者中获得了 MEG 和 ECoG 数据。将应用于发作间期 MEG 数据的三种源定位方法的结果分配到预定义的解剖区域。在 ECoG 中识别的发作间期棘波也被分配到这些区域。比较了每个 MEG 方法识别的区域与 ECoG。计算了每种 MEG 方法的敏感性和阳性预测值（PPV）。所有三种 MEG 方法均与 ECoG 棘波具有相似的总体相关性，但这些方法在检测的区域上有所不同。因此，反演模型的选择对磁场源成像的结果有意外的影响。结合反演方法并寻求共识可以提高特异性，代价是敏感性略有降低。将 MUSIC 与 SAM(g2) 相结合可获得最佳结果（敏感性=38%，PPV=82%）。
