iElectrodes: a novel tool for comprehensive depth and subdural grid electrode localization

J.P. PRINCICH; C. H. MURAVCHIK; H. N. PHILLIPS; T. A. BEKINSCHTEIN; A. BLENKMANN; JAMES B. ROWE; S. KOCHEN

Frontiers in NeuroInformatics

Frontiers

Año: 2017 vol. 11

1662-5196

The localization of intracranial electrodes is a fundamental step in the analysis ofinvasive electroencephalography (EEG) recordings in research and clinical practice.The conclusions reached from the analysis of these recordings rely on the accuracyof electrode localization in relationship to brain anatomy. However, currently availabletechniques for localizing electrodes from magnetic resonance (MR) and/or computerizedtomography (CT) images are time consuming and/or limited to particular electrode typesor shapes. Here we present iElectrodes, an open-source toolbox that provides robustand accurate semi-automatic localization of both subdural grids and depth electrodes.Using pre- and post-implantation images, the method takes 2?3 min to localize thecoordinates in each electrode array and automatically number the electrodes. Theproposed pre-processing pipeline allows one to work in a normalized space and toautomatically obtain anatomical labels of the localized electrodes without neuroimagingexperts. We validated the method with data from 22 patients implanted with a total of1,242 electrodes. We show that localization distances were within 0.56 mm of thoseachieved by experienced manual evaluators. iElectrodes provided additional advantagesin terms of robustness (even with severe perioperative cerebral distortions), speed (lessthan half the operator time compared to expert manual localization), simplicity, utilityacross multiple electrode types (surface and depth electrodes) and all brain regions.