3D Mapping of Static Magnetic Field Magnitude and Axial-Components around a total body 3T MRI clinical scanner

Francesco Girardello¹Maria Antonietta D'Avanzo²Massimo Mattozzi²Victorian Michele Ferro³Giuseppe Acri^3*Valentina Hartwig^1*

• ¹Institute of Clinical Physiology, Department of Biomedical Sciences, National Research Council (CNR), Pisa, Italy
• ²Department of Occupational and Environmental Medicine, INAIL, Rome, Italy
• ³Department of Biomedical, Dental, and Image Sciences, University of Messina, Messina, Italy

Objective. The technology employed in magnetic resonance imaging (MRI) systems has evolved continuously, resulting in MRI scanners with stronger static magnetic fields (SMF) B0, faster and stronger gradient magnetic fields, and more powerful radiofrequency transmission coils. The most well-known hazard associated with an MRI environment is the projectile effect due to Spatial Field Gradient (SFG). Furthermore, movement through the SFG generates a time-varying magnetic field, which in turn induces a voltage in body tissues. This has the potential to result in a range of physiological symptoms, including headache, nausea, vertigo, phosphenes, numbness, tingling, loss of proprioception, and balance disturbances. Approach. The methodology outlined in this study provides a comprehensive and reliable approach to creating a 3D map of the SMF (fringe field) around a clinical MRI facility. The methodology involves measuring the unperturbed B field, including magnitude and axial components, in specific points and subsequently performing a mathematical procedure involving fitting and interpolation. Main results. Fringe field magnitude and axial components 3D maps are presented for a 3T whole-body MRI scanner for clinical application located in a hospital facility. Significance. The map obtained could be used for a number of purposes, including the evaluation of hazard. This could be achieved by using digital tools to create a simulation of all types of MRI workers movements within the facility. The map could also be used for the training and education of MRI operators, with a view to establishing best practices. The estimation of magnetic field axial components represents a valuable enhancement, as these data can be used to calculate induced electric fields during rotational movements, such as those of the head or torso.