Simulation study of the potential hazards of cardiac stimulation by induced eddy-currents in modern MRI

In modern MRI, patients are exposed to strong, rapidly switching magnetic gradient fields that may be able to elicit nerve stimulation and cardiac stimulation. Based on a new, High Definition, Finite-Difference Time-Domain (HD-FDTD) method and a realistic inhomogeneous 10-mm-resolution human body model with tissue parameters, this paper firstly provides numerical results of an investigation into induced current spatial distributions inside human tissues when exposed to pulsed z-gradient fields. Then, various cardiac arrhythmia have been simulated based on our realistic heart-torso model and supposed that the induced current reaches the cardiac stimulation threshold. Simulation results show that the induced current is not strong enough to elicit ventricular fibrillation under nowadays several KHz switch frequency of gradient fields, but if raise the gradient field switch frequency further, it is with great risk to elicit ventricular fibrillation.