Biological effects and health implications in magnetic resonance imaging

Abstract

In this work, the safety aspects of the Magnetic Resonance Imaging and Spectroscopy (MRI/MRS) systems are reviewed. Focus is placed on the interaction between the electric and magnetic fields generated by such instruments and the human body. An understanding of these interactions has become ever more important with the push to higher field strengths. Knowledge of MRI safety can not only guide RF coil and pulse sequence design but can also affect sequence selections, thereby ensuring safe and efficient system operation. Due to the signal to noise advantages of high field MRI systems, increases in the static magnetic field are inevitable. However, in addition to the static magnetic field, power intense sequences, fast gradient switching, and localized imaging/spectroscopy all have the potential of subjecting the human body to intense magnetic and electric field fluctuations. This further accentuates the need for a detailed understanding of the effects of exposure to these fields. In this work, some of the issues addressed are new, while others are well established. In either case, it is hoped that this compilation will enable all of us to pay greater attention to these matters and increase the current state of understanding through novel experimental studies. The discussion broadens the range of radio frequency effects to the microwave limit. This was accomplished in view of the latest efforts for realization of ultra high field (UHF) human MRI. In this regard, recently constructed ultra high field whole body systems will provide a new testing ground for safety issues. The proliferation of high field (1.0–3.0 tesla), very high field (3.0–7.0 tesla), and ultra high field (≥7 tesla) whole body MRI's calls for a review of the safety literature that can guide future studies of critical health related issues. An effort has been made to present an up to date analysis of the biological effects within MR, covering a wide range of properties from cellular and physiological to clinical. © 2000 John Wiley & Sons, Inc. Concepts Magn Reson 12: 321–359, 2000