Safety and Effect of Magnetic Resonance Imaging

Abstract

This article reviews the safety considerations and biological effects of magnetic resonance imaging (MRI). It notes that the growing use of MRI as a diagnostic tool, and the increasing number of patients with implanted cardiovascular and other devices, require medical workers to receive MRI safety training, and that most MR-related injuries and deaths resulted from disobeying recognized safety regulations or from outdated knowledge about implants and equipment. The article describes the three magnetic fields used by an MRI scanner and their hazards: the static magnetic field, which can attract ferromagnetic objects, cause a 'projectile effect' and affect implanted devices; radiofrequency energy, which is absorbed by the body, is measured as the specific absorption rate (SAR) and can heat tissue, wires and leads; and rapidly changing gradient fields, which can stimulate peripheral nerves, induce currents in conductive cables and leads that may lead to arrhythmias, and contribute to scanner noise that may impair hearing. It also covers patient screening, safety terminology for implants and devices, imaging after device implantation, magnetic field, radiofrequency and cryogen risks, the in vitro, in vivo and ex vivo biological effects of static, gradient and radiofrequency fields, and SAR limits. The article advises consulting detailed safety sources, such as specialist websites, reference manuals or manufacturer information, before scanning any patient.

Abstract prepared by the editorial office from the full text of the article; the authors did not supply one.