Modeling of RF heating due to metal implants in MRI

Metal implants, even if non-ferromagnetic, may couple with the radiofrequency (RF) electromagnetic field used in magnetic resonance imaging (MRI) and cause a heating hazard. With the development of MRI as a tool for image-guided surgery, metal devices (e.g. guidewires) are being used in patients during MRI scans. This paper reviews the electromagnetic and bioheat transfer methods we have used to evaluate the safety of metal devices in MRI with respect to RF heating. We recommend updated regulatory guidelines to deal with the highly localized heating encountered with metal implants. We also recommend the use of the safety index as a useful measure of the RF safety of a device.