Jrad Nisrine, Kachenoura Amar, Merlet Isabelle, Bartolomei Fabrice, Nica Anca, Biraben Arnaud, Wendling Fabrice
IEEE Trans Biomed Eng. 2017 Sep;64(9):2230-2240. doi: 10.1109/TBME.2016.2633391. Epub 2016 Nov 29.
Interictal high-frequency oscillations (HFOs [30-600 Hz]) have proven to be relevant biomarkers in epilepsy. In this paper, four categories of HFOs are considered: Gamma ([30-80 Hz]), high-gamma ([80-120 Hz]), ripples ([120-250 Hz]), and fast-ripples ([250-600 Hz]). A universal detector of the four types of HFOs is proposed. It has the advantages of 1) classifying HFOs, and thus, being robust to inter and intrasubject variability; 2) rejecting artefacts, thus being specific.
Gabor atoms are tuned to cover the physiological bands. Gabor transform is then used to detect HFOs in intracerebral electroencephalography (iEEG) signals recorded in patients candidate to epilepsy surgery. To extract relevant features, energy ratios, along with event duration, are investigated. Discriminant ratios are optimized so as to maximize among the four types of HFOs and artefacts. A multiclass support vector machine (SVM) is used to classify detected events. Pseudoreal signals are simulated to measure the performance of the method when the ground truth is known.
Experiments are conducted on simulated and on human iEEG signals. The proposed method shows high performance in terms of sensitivity and false discovery rate.
The methods have the advantages of detecting and discriminating all types of HFOs as well as avoiding false detections caused by artefacts.
Experimental results show the feasibility of a robust and universal detector.
发作间期高频振荡（HFOs[30 - 600Hz]）已被证明是癫痫相关的生物标志物。本文考虑了四类HFOs：伽马波（[30 - 80Hz]）、高伽马波（[80 - 120Hz]）、涟漪波（[120 - 250Hz]）和快涟漪波（[250 - 600Hz]）。提出了一种通用的这四种类型HFOs的检测器。它具有以下优点：1）对HFOs进行分类，因此对个体间和个体内的变异性具有鲁棒性；2）排除伪迹，因此具有特异性。
调整Gabor原子以覆盖生理频段。然后使用Gabor变换来检测癫痫手术候选患者记录的颅内脑电图（iEEG）信号中的HFOs。为了提取相关特征，研究了能量比以及事件持续时间。优化判别比，以便在四种类型的HFOs和伪迹中实现最大化。使用多类支持向量机（SVM）对检测到的事件进行分类。当已知真实情况时，模拟伪真实信号以测量该方法的性能。
在模拟和人体iEEG信号上进行了实验。所提出的方法在灵敏度和错误发现率方面表现出高性能。
该方法具有检测和区分所有类型HFOs以及避免由伪迹引起的错误检测的优点。
实验结果表明了一种鲁棒通用检测器的可行性。
