A magnetic resonance imaging system (302) includes a magnet (306) for generating the magnetic field within an imaging zone 318. The magnet generates a magnetic field with a zero crossing (346, 404) outside of the imaging zone. The medical apparatus further includes a gantry (332) configured for rotating a ferromagnetic component (336, 510) about a rotational axis (333). A magnetic correcting element (348, 900, 1000) is located on a radial path (344, 504) perpendicular to the rotational axis. The magnetic correcting element is positioned on the radial path such that change in the magnetic field within the imaging zone due to the ferromagnetic component is reduced.
