Safety aspects of magnetic resonance imaging for pacemaker holders

In this paper radiofrequency power absorption and temperature elevation in the thorax of a pacemaker (PM) holder exposed to the field generated by a 1.5 T (64 MHz) magnetic resonance imaging (MRI) apparatus have been numerically studied. A pacemaker model, constituted by a metallic box equipped with a catheter, has been inserted inside an anatomical body model that is placed inside the birdcage MRI antenna. The results obtained for an input power of 60 W (typical value for MRI examinations) show that SAR safety limits proposed in international guidelines are met, while temperature increments are well above the prescribed recommendations. In particular, by neglecting the blood perfusion, temperature increments up to 30degC are computed at the catheter tip; these reduce to about 10degC if a complete thermal model is considered, still remaining over safety limits.