Publication details

Relative entropy is an easy-to-use invasive electroencephalographic biomarker of the epileptogenic zone

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Authors

TRAVNICEK Vojtech KLIMES Petr CIMBÁLNÍK Jan HALAMEK Josef JURAK Pavel BRINKMANN Benjamin BALZEKAS Irena ABDALLAH Chifaou DUBEAU Francois FRAUSCHER Birgit WORRELL Greg BRÁZDIL Milan

Year of publication 2023
Type Article in Periodical
Magazine / Source Epilepsia
MU Faculty or unit

Faculty of Medicine

Citation
Web https://onlinelibrary.wiley.com/doi/10.1111/epi.17539
Doi http://dx.doi.org/10.1111/epi.17539
Keywords drug-resistant epilepsy; iEEG; SOZ localization
Attached files
Description Objective: High-frequency oscillations are considered among the most promising interictal biomarkers of the epileptogenic zone in patients suffering from pharmacoresistant focal epilepsy. However, there is no clear definition of pathological high-frequency oscillations, and the existing detectors vary in methodology, performance, and computational costs. This study proposes relative entropy as an easy-to-use novel interictal biomarker of the epileptic tissue.Methods: We evaluated relative entropy and high-frequency oscillation biomarkers on intracranial electroencephalographic data from 39 patients with seizure-free postoperative outcome (Engel Ia) from three institutions. We tested their capability to localize the epileptogenic zone, defined as resected contacts located in the seizure onset zone. The performance was compared using areas under the receiver operating curves (AUROCs) and precision-recall curves. Then we tested whether a universal threshold can be used to delineate the epileptogenic zone across patients from different institutions.Results: Relative entropy in the ripple band (80-250 Hz) achieved an average AUROC of .85. The normalized high-frequency oscillation rate in the ripple band showed an identical AUROC of .85. In contrast to high-frequency oscillations, relative entropy did not require any patient-level normalization and was easy and fast to calculate due to its clear and straightforward definition. One threshold could be set across different patients and institutions, because relative entropy is independent of signal amplitude and sampling frequency.Significance: Although both relative entropy and high-frequency oscillations have a similar performance, relative entropy has significant advantages such as straightforward definition, computational speed, and universal interpatient threshold, making it an easy-to-use promising biomarker of the epileptogenic zone.
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