A magnetic field generating apparatus for use in magnetic resonance imaging (MRI) is disclosed. The apparatus includes an annular magnet field generator defining a patient bore, a gradient coil disposed between the magnetic field generator and the patient bore, a first set of shim elements, and a second set of shim elements. The patient bore has an imaging volume, a z-axis, and an isocenter. The first set of shim elements are disposed at a region between the magnetic field generator and the imaging volume, and the second set of shim elements are disposed at the region at a location having equal to or greater than a specified Z/R ratio, where Z defines an axial distance from the isocenter and R defines a radial distance from the z-axis.