The present invention is a saturated ferromagnetic structure for controlling the homogeneity of the primary magnet field of a magnet in a Magnetic Resonance Imaging system. The structure has a plurality of coaxial laminations disposed thereon about a central axis of the structure, such that the structure is magnetically saturated and generates a magnetic field parallel to the central axis. In use the structure functions to improve the homogeneity of the primary magnetic field. The structure further allows for a MRI system with a less confined patient space than is currently available with known MRI systems.