Restoration of electrophysiological signals distorted by inductive effectsof magnetic field gradients during MR sequences

A generally applicable method for almost complete suppression of signal art ifacts on electrophysiological signals caused by B-0-gradient switching (gr adient noise) is presented. The method is demonstrated for electrocardiogra ms (ECGs) but can also be used for other electrophysiological signals. It t akes advantage of the fact that under certain conditions, the effect of swi tching the Be-field gradient upon an electrophysiological signal can be mod eled as a linear time-invariant system and fully characterized by pulse res ponse functions. It is shown how the system's pulse response functions of t he X, Y, and Z gradients can be determined and how gradient noise can be el iminated efficiently. The elimination of gradient noise by the proposed met hod causes in the current arrangement a constant delay of 128 msec, which i s acceptable for patient monitoring and magnetic resonance sequence trigger ing. (C) 1999 Wiley-Liss, Inc.