Abstract
Objective Whole-head on scalp magnetoencephalography (osMEG) is a novel, cutting-edge functional neuroimaging technique that positions MEG sensors closer to the cortical sources. OsMEG allows both for free head movements and improved spatial resolution compared to conventional MEG. OsMEG thus might improve clinical epilepsy evaluations. However, it remains largely unknown how osMEG characterizes epileptic activity. Here, we aimed to compare epileptic activity source estimation accuracy of osMEG, high-density EEG (hd-EEG), conventional MEG (convMEG) and subdural EEG (sbdEEG).
Method IED and seizure onset zone source estimations of osMEG, hdEEG, convMEG and sbdEEG were evaluated using equivalent current dipoles. Cancellation index of all non-invasive modalities were calculated and compared statistically. To further investigate any similarity between osMEG and sbdEEG, representational similarity analysis was used to compare IED source estimations of these two modalities.
Results We found that osMEG IED source estimations were significantly (p<0.05) better than both convMEG and hdEEG. Furthermore, osMEG mesial temporal lobe SOZ source estimations were superior to those of convMEG and hdEEG. OsMEG cancellation index did not differ significantly from convMEG. Interestingly, comparing osMEG and sbdEEG IED source estimation demonstrated that osMEG might be less sensitive to source directions than convMEG.
Conclusion We demonstrated that whole-head osMEG exhibited very accurate non-invasive IED and SOZ source estimations, better than both hd-EEG and convMEG.
Significance OsMEG has a promising potential to become a safe, highly sensitive neuroimaging modality for whole head epilepsy evaluations.
Highlights
Analysis of novel on-scalp MEG (osMEG) sensors in epilepsy evaluations
Compares osMEG, EEG, conventional MEG & intracranial EEG epilepsy source estimations
Our study demonstrates potential great clinical value of osMEG whole-head sensors
Competing Interest Statement
The authors have declared no competing interest.
Abbrevations
- osMEG
- on scalp magnetoencephalography
- convMEG
- conventional magnetoencephalography
- hdEEG
- high density electroencephalography
- sbdEEG
- subdural electroencephalography
- IED
- interictal epileptiform discharge
- OPM
- optically pumped magnetometer
- highTc SQUID
- high critical temperature superconducting quantum interference devices
- SOZ
- seizure onset zone
