An activity of the DRCMR is the simultaneous acquisition of functional MRI (fMRI) and electrical signals coming from brain activity (electroencephalography, EEG recording). The combination of the two techniques can improve both source localisation in EEG and temporal resolution in fMRI. Briefly, EEG can measure when there is brain activity and fMRI can measure where it happens. Hence EEG-fMRI is widely believed to be a technique that will increase the understanding of processes and networks in the brain, and will provide improved diagnosis of particular diseases, for example, when used for pre-surgical planning in epilepsy. However, measuring EEG and fMRI simultaneously is a highly difficult task due to the interference between the two recordings.
The acquisition of MR images causes an artefact signal in the EEG trace that is about 3 orders of magnitude larger than the actual EEG signal. This is highly demanding both for the hardware used to record EEG signals during scanning and for the analysis software. Lars and Christian G. Hanson have headed a group developing a novel method for recording EEG and fMRI simultaneously. The approach uses a special modulator together with the scanner for recording both EEG and fMRI data. Similar to the so-called “Magstripe technique” used for encoding of soundtracks in movies, the EEG signals are encoded in the MR images outside the visible region. A proof-of-concept study has been accepted for publication in Journal of Magnetic Resonance Imaging. The technique and especially the developed hardware has matured much since the initial studies and in 2006 alpha-EEG recording was demonstrated using the method. The electronics developer of the group, Christian G. Hanson, has constructed a highly flexible 8-channel modulator for the purpose. The method is simple to use, sensitive, inexpensive and more robust than traditional methods. The analysis is also suitable for integration on the scanner, even as the data are being acquired (real-time EEG-fMRI). PhD student Arnold Skimminge enrolled in the ITMAN graduate school at the Technical University of Denmark is working on these issues. The patent rights for the Magstripe method are now claimed by an independent spin-off company MRIware founded for that purpose.
Link to the Magstripe homepage
