Removal of ballistocardiogram artifacts exploiting second order cyclostationarity

Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) is increasingly used to monitor the brain activity. The interactions between the scanner magnetic field, the patient´s body, and the EEG electrodes generate a pulsation artifact called ballistocardiogram (BCG) which is synchronized with the patient´s heart beat. The BCG artifact is considered here as the sum of a number of independent cyclostationary components having the same cycle frequency. Cyclostationary source extraction (CSE) is used here to remove BCG artifact. The results are compared with the results of benchmark BCG removal techniques. It is shown that visual evoked potentials (VEPs) recorded inside the scanner and processed using the proposed method are more correlated with the VEPs recorded outside the scanner. Moreover, the presence of electrocardiogram (ECG) data is not necessary in this method as the cycle frequency of the BCG is directly computed from the contaminated EEG signals.