Electromagnetic Field Mechanisms and Safety Implications in Magnetic Resonance Imaging: A Contemporary Review

Abstract

Magnetic resonance imaging (MRI) relies on static, gradient, and radiofrequency (RF) electromagnetic fields to generate high-resolution diagnostic images. As MRI technology continues to advance, comprehensive knowledge of these fields is increasingly important for safe and effective clinical practice. However, existing evidence remains fragmented, while limited technical understanding may affect protocol selection, implant assessment, patient handling, and risk management. Therefore, this review aims to explain the principles of MRI electromagnetic fields, examine their effects on image formation, system performance, biological tissue interactions, and implanted medical devices, and synthesise current evidence on their associated safety implications. An integrative narrative review was conducted using structured literature searches, followed by narrative and matrix synthesis of 40 sources including review articles, experimental and simulation studies, clinical investigations, safety guidelines, consensus statements, and organisational studies. The findings indicate that static magnetic fields facilitate nuclear alignment but introduce projectile, vestibular, and implant-displacement hazards. Gradient magnetic fields provide spatial encoding but may induce peripheral nerve stimulation, cardiac magnetostimulation, and acoustic exposure, whereas RF fields enable proton excitation while presenting tissue-heating and implant-related thermal risks. MRI safety is influenced by multiple interacting factors, including scanner configuration, implant characteristics, patient anatomy, operating conditions, staff competency, and institutional governance. Integrating electromagnetic-field principles with evidence-based system design, rigorous safety protocols, and patient-specific risk assessment is essential for ensuring high-quality imaging while minimising patient and occupational risks.