Magnetic susceptibility artifacts in magnetic resonance imaging: calculation of the magnetic field disturbances

IEEE Transactions on Magnetics 32:1645-1648 (1996)

Stéphane Balac
IRMAR, Université de Rennes 1
Campus de Beaulieu
35042 Rennes Cedex, France

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

Abstract

In Magnetic Resonance Imaging, inhomogeneities of the static magnetic field lead to perturbations in the resulting images, called artifacts. Our goal is to numerically compute the disturbances induced by a material having magnetic properties different from that of the surrounding tissues (e.g. a paramagnetic implant). Since the method is linked to an artifact reconstruction model to get simulated images, it has to be well suited for general three dimensional geometries and to provide very accurate results in a fine grid around the implant. Our method is based on a surface integral representation of the magnetic field. An analytical expression is derived when the boundary of the domain can be meshed in flat panels. For curved surfaces a numerical quadrature scheme is implemented.