Power Absorption and Temperature Elevation Produced by Magnetic Resonance Apparatus in the Thorax of Patients With Implanted Pacemakers

In this paper, 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 studied. An anatomical body model has been placed in two different positions inside the birdcage MRI antenna. Various PM models, constituted by a metallic box equipped with different kinds of catheters, have been placed in some typical positions inside the human thorax. The obtained results show that in the absence of the PM, both specific absorption rate (SAR) levels and temperature increments are compliant with the recommendations contained in international guidelines. When a realistic model of the PM is inserted inside the body, the limits on the whole body SAR are still met, the limits on SAR averaged over 10 g are exceeded for some catheter geometries, while temperature increments at the catheter tip are above the prescribed recommendations.