MAGNETIC-SUSCEPTIBILITY ARTIFACTS IN MAGNETIC-RESONANCE-IMAGING - CALCULATION OF THE MAGNETIC-FIELD DISTURBANCES

In Magnetic Resonance Imaging, Inhomogeneities of the static magnetic field lead to perturbations in the resulting images, called artifacts. Our goal Is to compute numerically the disturbances induced by a mate rial having magnetic properties different from that of the surrounding tissues. The method is linked to an artifact reconstruction model to get simulated Images. This model needs very accurate results In a fine three-dimensional grid around the implant. The use of standard method s would lead to solve very large systems. Our method is based on a sur face integral representation of the magnetic field. To implement it in an efficient way, an analytical expression is derived when the bounda ry of the domain can be meshed in flat panels. For curved surfaces a n umerical quadrature scheme Is implemented.