Ballistocardiographic artifact removal from simultaneous EEG/FMRI recording by means of canonical correlation analysis

The electroencephalogram (EEG) is a standard technique to record and study the brain activity with a high temporal resolution. Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) is a non-invasive imaging method that allows the localization of activated brain regions with a high spatial resolution. The co-recording of these two complementary modalities can give new insights into how the brain functions. However, the interaction between the strong electromagnetic field (3T) of the MR scanner and the currents recorded by the electrodes placed on the scalp generates artifacts that obscure the EEG and diminish its readability. In this work we used canonical correlation analysis (CCA) in order to remove the ballistocardiographic artifact (BCGa). CCA is applied to two consecutive windows in order to take into account both spatial and temporal information. We showed that users can easily remove the artifact through a graphical user interface by adjusting the number of components to be removed according to visual inspection of the signal, its power spectrum, the cumulative explained variance and the correlation coefficients