Xiang J, Holowka S, Qiao H, Sun B, Xiao Z, Jiang Y, Wilson D, Chuang S
Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, Canada.
Neurol Clin Neurophysiol. 2004 Nov 30;2004:98.
Conventional visual identification of epileptic spike is a challenging problem in the clinical application of magnetoencephalography (MEG). More importantly, the conventional method has problems of detecting other abnormalities such as high frequency oscillation in the human epileptic brain. The objective of this study was to develop a new approach using magnetic spectral analysis and spatial filtering. Twelve patients with seizure have been studied with a whole cortex MEG system. Fifteen epochs were recorded for each patient; each epoch was 120 seconds. Neuromagnetic spectrum was analyzed using a new method called accumulated spectrogram. Focal increases of spectral power were localized using synthetic aperture magnetometry (SAM). The MEG results were then compared with clinical findings. Focal increases of spectral power have been identified in all patients (12/12, 100%). The locations of the focal increases of spectral power were in agreement with dipole locations of spikes in 9 patients (9/12, 75%). A comparison between MEG results and clinical findings indicated that SAM revealed focal epileptic activities in two patients when dipole fitting failed. The results suggest that epileptic regions could be quantitatively identified and accurately localized using accumulated spectrogram and SAM. In comparison to visual identification of spike, the new approach is objective and sensitive, and provides the possibility of analyzing much wider frequency bands.
在脑磁图（MEG）的临床应用中，通过传统视觉识别癫痫棘波是一个具有挑战性的问题。更重要的是，传统方法在检测人类癫痫大脑中的其他异常情况（如高频振荡）时存在问题。本研究的目的是开发一种使用磁谱分析和空间滤波的新方法。使用全脑皮层MEG系统对12例癫痫患者进行了研究。为每位患者记录了15个时段；每个时段为120秒。使用一种称为累积频谱图的新方法分析神经磁谱。使用合成孔径磁测法（SAM）对频谱功率的局灶性增加进行定位。然后将MEG结果与临床发现进行比较。在所有患者中均发现频谱功率局灶性增加（12/12，100%）。频谱功率局灶性增加的位置与9例患者（9/12，75%）棘波的偶极子位置一致。MEG结果与临床发现的比较表明，在偶极子拟合失败时，SAM在2例患者中揭示了局灶性癫痫活动。结果表明，使用累积频谱图和SAM可以定量识别癫痫区域并准确定位。与视觉识别棘波相比，新方法客观、敏感，并提供了分析更宽频带的可能性。
