The purpose of this paper is to present a novel parametric model for Magnetic Resonance (MR) induced artifacts contaminating electrophysiological signals (ECG, EEG, EMG, etc.) recorded simultaneously during MRI. The aim to construct an analytical representation of these artifacts is of great importance as it helps to understand and make appropriate hypotheses about the artifacts' generation process. The model presented in this paper assumes a periodic and stationary nature of these artifacts. Statistical KPSS tests were applied to confirm that observed artifacts are weak-sense stationary. The model based on a sum of sinusoids of different amplitudes, frequencies and phase delays {A, f, Φ} was most suited to represent these artifacts. The sinusoidal model parameters {A, f, Φ} were estimated by BFGS optimization. The lowest mean square error (MSE) is used to determine the model with the optimum parameters. Pearson's correlation coefficients were used as indices to evaluate the accuracy of the calculated model.

We have developed an experimental setup as an in vitro research tool for studying the contamination of electrophysiological signals (EPS) by MRI environment; particularly, when due to the switched gradient-induced potentials. The system is composed of: 1) a MRI compatible module for the transmission of the EPS into the MRI tunnel, 2) a gelatin-based tissue-mimicking phantom, placed inside the tunnel, in which EPS is injected, 3) a detection module composed of a five input channel MRI compatible transmitter placed inside the tunnel, allowing an on-site pre-amplification of the bio-potentials and their transmission, via an optical fiber cable, to a four filtered output per channel receiver (350 Hz, 160 Hz, 80 Hz, and 40 Hz, for a total of 20 channels) placed in the control room, and 4) a signal processing algorithm used to analyze the generated induced potentials. A set of tests were performed to validate the electronic performances of the setup. We also present in this work an interesting application of the setup, i.e., the acquisition and analysis of the induced potentials with respect of the slice orientation for a given MRI sequence. Significant modifications of the time and frequency characteristics were observed with respect to axial, coronal or sagittal orientations.