MRI Safety: RF-Induced Heating near Straight Wires

Abstract

One of the most crucial magnetic resonance (MR) safety concerns is related to excessive heating of metallic implants by the radio frequency (RF) magnetic field. In this study, heating by the MR imaging (MRI) RF magnetic field of bare and insulated wires was evaluated to model the heating of medical lead wires. Currents induced in the wire were calculated using the method of moments. The electric field in the tissue surrounding the wire was calculated to determine the power deposition. From the power, the temperature rise was calculated using the bioheat equation. For bare wires, the calculated and maximal temperature rise, which is about 28 degrees C, occurred for a length of 20 cm. For lengths exceeding 20 cm, temperature rises for the insulated wires were greater, and the resonance length exceeded 40 cm.