Use of a Full-Size Human Model for Evaluating Metal Implant Heating During Magnetic Resonance Imaging

Abstract

Magnetic resonance imaging (MM) and computer tomography (CT) have been used routinely in medical diagnosis. MRI is often preferred to CT because of its better soft-tissue resolution and lack of risk from ionizing radiation. However, the use of MRI involves magnetic and radio frequency (RF) exposures. In a strong static magnetic field and a pulsed RF field, five potential adverse effects are anticipated with metallic implants: 1) force on the implant by the strong static magnetic field, 2) current induced in the implants by the RF field, 3) damage of implant electronic circuitry by RF exposure, 4) MRI image distortion caused by the implant, 5) implant and adjacent tissue heating due to absorption of RF energy. Only the last of these, RF tissue heating, will be addressed in this paper. The present Food and Drug Administration (FDA) recommended limits of RF heating during MRI scanning are 1{\textdegree}C in the brain, 2{\textdegree}C in the torso and 3{\textdegree}C in the extremities[1].