Mathematical modeling and numerical simulation of magnetic susceptibility artifacts in Magnetic Resonance Imaging

Stéphane Balac
Université de Bretagne Occidentale
6, avenue V. Le Gorgeu, BP 809
29285 Brest cedex, France

Gabriel Caloz
IRMAR, Université de Rennes 1
Campus de Beaulieu
35042 Rennes Cedex, France

Abstract

The technique used to spot information in Magnetic Resonance Imaging (MRI) is based on electromagnetic fields. To a strong homogeneous magnetic field (order of magnitude around one Tesla) is added a linearly varying field (around $10^{-2}$ Tesla per meter). When these fields are disturbed by the presence of a paramagnetic material in the sample for instance, the resulting image is usually distorted, these distortions are called artifacts. Our goal is to present a method, assuming the field disturbances are known, to construct the images. A mathematical model of the MRI process is developed. The way the images are distorted in intensity and shape is explained and an algorithm to simulate magnetic susceptibility artifacts is deduced.