Electromagnetics in magnetic resonance imaging

Magnetic resonance imaging (MRI) is a powerful new imaging method, which pr oduces cross-sectional tomographic and three-dimensional images similar to those of x-ray computed tomography (CT). However, rather than relying on ha rmful ionizing radiation, MRI is based on the interaction between RF fields and certain atomic nuclei in the body, when they are in the presence of a strong magnetic field. An MRI system is one of the few complete systems in which the design relies heavily upon a knowledge of electromagnetics. In th is article, we give a tutorial on the electromagnetic analysis and design o f three key components of an MRI system, namely, the magnet, the gradient c oil, and the radiofrequency (RF) coil. We will also discuss the analysis an d characterization of the interactions of RF electromagnetic fields with bi ological subjects.