Visual inspection of interictal epileptiform discharges (IEDs) in multi―channel magnetoencephalography (MEG) requires a time―consuming evaluation process and often leads to inconsistent results among interpreters. In most clinical situations, the application of independent component analysis is restricted to artifact rejection. Here, we propose a novel extraction method for IEDs using a T/k type of blind source separation (BSST/k). We conducted comparisons of the results of BSS components with those obtained by visual inspection in sensor―space analysis for seven patients with focal epilepsy. BSST/k provided better signal decomposition of variable IEDs in one dominant component compared with sensor―space analysis. The dominant component was able to uncover IEDs that could not be detected by visual inspection, showing sufficient sensitivity along with high specificity. BSST/k was able to visualize the spreading signals over multiple channels into a single component from a single epileptogenic zone. BSST/k can be applied to focal epilepsy with a simple parameter setting. Based on the above results, we plan to develop the support analysis tool for visual identification of IEDs in future.
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