[MRI safety : Principles, risks and protective measures]

Despite its advantages, the application of magnetic resonance imaging (MRI) involves specific safety risks, primarily caused by the strong static magnetic field and the alternating electromagnetic fields, in particular the high-frequency (HF) and gradient fields, posing hazards to both patients and medical personnel. Particularly problematic are ferromagnetic objects that can enter the magnetic field uncontrolled, potentially causing severe injuries. Additionally, metal implants can interact undesirably with the MRI system, leading to tissue heating or malfunctioning. The gradient fields required for spatial encoding can cause unwanted nerve stimulations. The HF fields can cause electrically conductive materials to overheat, potentially resulting in burns; however, appropriate safety measures, such as labeling, specialized safety training and the automatic monitoring of critical safety parameters can extensively minimize these risks.