Document Detail


Improving the excess kurtosis (g2) method for localizing epileptic sources in magnetoencephalographic recordings.
MedLine Citation:
PMID:  25281474     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
OBJECTIVE: To suggest ways to apply the excess kurtosis estimator g2, in the detection of epileptic activity with magnetoencephalography, while avoiding its bias towards detecting high-amplitude, infrequent events.
METHODS: Synthetic aperture magnetometry (SAM), combined with g2, was applied using window lengths ranging from 0.125s to 32s and with sum and maximum metrics on simulated data and recordings of two focal epilepsy patients.
RESULTS: Comparing sources with different spike rates (two per second and one per 2s), the sum metric was most efficient when using a window of 0.25s. Simulations showed that the sum metric is insensitive to spike frequency when the window includes more than one spike. SAM(g2) images from long segments with maximum metric resulted in misleading images, showing the strongest activity away from the lesions.
CONCLUSIONS: Using a sliding window and the sum metric is beneficial when imaging interictal spikes and status epilepticus. Windows should be short enough not to include more than one interictal event. For continuous events such as electrographic seizures windows should contain baseline data and the epileptic event.
SIGNIFICANCE: The sliding window and metric should be set according to the suggested guidelines when using SAM(g2) for presurgical evaluation.
Authors:
Yuval Harpaz; Stephen E Robinson; Mordekhay Medvedovsky; Abraham Goldstein
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-9-16
Journal Detail:
Title:  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology     Volume:  -     ISSN:  1872-8952     ISO Abbreviation:  Clin Neurophysiol     Publication Date:  2014 Sep 
Date Detail:
Created Date:  2014-10-4     Completed Date:  -     Revised Date:  2014-10-5    
Medline Journal Info:
Nlm Unique ID:  100883319     Medline TA:  Clin Neurophysiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014 International Federation of Clinical Neurophysiology. All rights reserved.
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