Analysis and localization of epileptic events using wavelet packets
Analysis and localization of epileptic events using wavelet packets
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DOI：
10.1016/s1350-4533(01)00096-0
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发表时间：
2001-11-01
影响因子：
2.2
通讯作者：
Medina, V
中科院分区：
文献类型：
--
作者：
Gutiérrez, J;Alcántara, R;Medina, V
本文使用时频表示比较了之前研究中获得的结果（Wigner-Ville，Choi-Williams and Parametric）和小波变换与小波包函数获得的结果进行比较，以显示在分析人类难治性癫痫的ECoG记录中关于其质量的新发现：本文用正交、双正交和非正交四种小波基对21例患者的临床资料进行了分析和处理。对这些函数进行比较，以测试它们代表ECoG峰值的质量。并计算了不同尺度下小波系数的能量。最好的结果被发现与5-7尺度上的双正交-6.8小波，它给出了0.92的灵敏度，但具有高比例的假阳性，这种表示与尖峰事件的时间和持续时间高度相关。为了改善这些结果，我们研究了小波包系数的能量。我们发现，重构小波包系数在4和9节点包含重要的信息，以表征锋电位事件。这些节点的重建系数相乘，并且该乘积与尖峰事件在时间和持续时间上高度相关。通过这种方法，我们在四个水平上使用相同的双正交6.8小波，将灵敏度提高到0.96。使用这种技术，我们不会牺牲计算时间：896个样本仅在0.16 s内处理，因此可以在线显示尖峰散射路径，因为896个样本（7 s）/16个通道在3.13 s内处理。(C)2002年妇女平等研究所。爱思唯尔科技有限公司版权所有。
This article compares results obtained in previous studies using time-frequency representations (Wigner-Ville, Choi-Williams and Parametric) and the wavelet transform with those obtained with wavelet packet functions to show new findings about their quality in the analysis of ECoG recordings in human intractable epilepsy: data from 21 patients have been analyzed and processed with four types of wavelet functions, including Orthogonal, Biorthogonal and Non-Orthogonal basis. These functions were compared in order to test their quality to represent spikes in the ECoG. The energy based on the wavelet coefficients to different scales was also calculated. The best results were found with the biorthogonal-6.8 wavelet on 5-7 scales, which gave 0.92 sensitivity, but with a high percentage of false positives; this representation was highly correlated with spike events on time and duration. To improve these results we have studied the wavelet packet coefficients energy. We found that reconstruction wavelet packet coefficients at 4 and 9 nodes contain significant information to characterize the spike event. These nodes' reconstruction coefficients were multiplied and this product was highly correlated with spikes events on time and duration. With this procedure we improved the sensitivity up to 0.96 with the same biorthogonal-6.8 wavelet at four levels. With this technique we do not sacrifice computation time: 896 samples are processed at only 0.16 s, so that it is possible to show the spike scattering path on line, because 896 samples (7 s)/16 channels are processed at 3.13 s. (C) 2002 IPEM. Elsevier Science Ltd. All rights reserved.