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Given the high technological complexity of magnetic resonance imaging (MRI) systems, there is particular concern for potential harm. Safety issues arise from the three main components of the MRI system: its main static magnetic field, which is always on in superconducting magnets, and the switched radiofrequency electromagnetic fields and gradient magnetic fields that are activated during imaging. This article reviews published literature mainly from 2015 with regard to these general safety considerations and their interaction with implanted medical devices. Furthermore, an update on regulatory issues will be provided along with an overview of miscellaneous other safety aspects that are related to an MRI exam but do not arise from the technology per se.

Magnetic resonance imaging (MRI) is a widely used and powerful imaging technique for non-invasive clinical diagnosis. The absorbed radiofrequency (RF) energy must be carefully managed, as MRI presents one of the highest RF exposures to humans. Temperature increases in the patient caused by high-level RF exposure is a major safety concern in MRI, potentially causing local thermal tissue damage or systemic overheating. This review article summarizes recent findings in MR safety research, including the clear distinction between exposures of patients with and without implants; evaluates the advantages and limitations of numerical simulations for RF safety assessment in MRI; and discusses the need for additional research at high RF exposure levels and in novel MRI systems.