Chapter 20 - MRI Safety and Neuromodulation Systems

Abstract

This chapter provides an overview of MRI bioeffects, discusses various MRI safety topics and issues, presents evidence-based guidelines to ensure safety for patients and staff members, and describes safety information for implants and devices with an emphasis on neuromodulation systems. Most MR systems in use today operate with static magnetic fields ranging from 0.2-Tesla to 3-Tesla. Although there have been some reports of potentially injurious effects of static magnetic fields on isolated cells or organisms, none of these effects has been verified or firmly established as a scientific fact. The quantitative analysis of these mechanisms indicates that they are below the threshold of significance with respect to long-term adverse bioeffects. During MRI procedures, gradient or “time-varying” magnetic fields may stimulate nerves or muscles by inducing electrical fields in patients. However, the current safety standards for gradient magnetic fields associated with present-day scanners appear to adequately protect patients from potential hazards or injuries. The establishment of thorough and effective screening procedures for patients and other individuals is one of the most critical components of a program that guards the safety of all those preparing to undergo MRI procedures or to enter the MRI environment. An important aspect of protecting patients and individuals from MR system-related accidents and injuries involves an understanding of the risks associated with the various implants, devices, accessories, and other objects that may cause problems in this setting. Certain aspects of screening patients for MRI examinations may take place during the scheduling process, which must be conducted by a healthcare professional specially trained in MRI safety.