Independent source resolution: an alternative MEG figure of merit

Abstract

Event Abstract Back to Event Independent source resolution: an alternative MEG figure of merit Stephen Robinson1* 1 Henry Ford Hospital, Athena project team, United States Independent source resolution (ISR) is a proposed method for characterizing the ability of a MEG sensor array and accompanying software to discriminate among signals arising from multiple closely spaced cortical sources. It is often stated that MEG can localize a single dipole source within a few millimeters. In practice, localization accuracy and source resolution depend upon signal-to-noise, the presence of interfering sources, and coregistration. Having excellent resolution of single sources does not necessarily imply resolution of multiple sources. The primary clinical application of MEG is localization of epileptic cortex. Invasive intracranial EEG is the standard for presurgical diagnosis. ECoG is used to identify the ictal onset zone (IOZ) by mapping normal and abnormal activity on a 10 mm grid. In order to determine if this can be achieved using existing MEG helmets, an array of 64 dipole sources was simulated on an 8x8 grid with 10 mm spacing. Each dipole was assigned an independent random time series. The MEG signal was then simulated using the forward solution for each source and adding simulated brain and sensor noise. Next, a scalar LCMV beamformer was used to estimate the source waveforms at the location of each dipole. Last, a matrix of the correlation of the simulated versus recovered signals is computed. The deviation of this matrix from the identity matrix provides a measure of ISR. This method was used to evaluate the performance of several whole-head MEG instruments and high resolution EEG. Results indicate that none of the existing MEG instruments or scalp EEG have sufficient ISR to substitute for ECoG grids. ISR of these instruments is limited by the gap between sensors and the cortex. A proposed high-resolution MEG sensor array with a smaller gap and inter-sensor spacing was also simulated and shown to have sufficient ISR for noninvasive IOZ mapping. This research was supported by NIH/NINDS Grant R01 NS30914. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: MEG Modeling Citation: Robinson S (2010). Independent source resolution: an alternative MEG figure of merit. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00049 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Mar 2010; Published Online: 21 Mar 2010. * Correspondence: Stephen Robinson, Henry Ford Hospital, Athena project team, Detroit, United States, robinson@neurnis.neuro.hfh.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Stephen Robinson Google Stephen Robinson Google Scholar Stephen Robinson PubMed Stephen Robinson Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.