Electric fields induced in a human heart by MRI gradient coils: a finite element study

A three-dimensional finite element model (FEM) representing the conductive anatomy of the human thorax is used to study the myocardial electric fields induced by the gradient coils used in echo-planar magnetic resonance imaging (MRI). The influence of model shape, conductive inhomogeneity, and anisotropy on the spatial distribution of the induced myocardial electric field and it's maximum (|E/spl I.oarr/|/sub max/) is also investigated. Results show that model shape and conductive inhomogeneity substantially influence myocardial electric field distributions and |E/spl I.oarr/|/sub max/, while the impact of skeletal muscle anisotropy is modest. Computed maximum magnitudes of the myocardial electric fields induced by typical echo-planar MRI gradient coils suggest that contemporary MRI devices operate well below the threshold for myocardial stimulation.