The invention relates to a magnetic resonance imaging (MRI) system (1)
comprising an examination volume (111), a main magnet system (13) for
generating a main magnetic field (B.sub.0) in the examination volume in a
Z-direction, a gradient magnet system (19) for generating gradients of
the main magnetic field, and an anti-vibration system (33) for reducing
vibrations of the gradient magnet system caused by a mechanical load
(M.sub.X, M.sub.Y) exerted on the gradient magnet system as a result of
electromagnetic interaction between the main magnetic field and
electrical currents in the gradient magnet system. According to the
invention the anti-vibration system (33) comprises a balance member (39),
which is coupled to the gradient magnet system (19) by means of an
actuator system (51) and a coupling device (49) allowing displacements of
the balance member relative to the gradient magnet system. The MRI system
(1) also has a control system (81) which controls the actuator system in
such a manner that the actuator system exerts upon the balance member a
compensating mechanical load (M.sub.CX, M.sub.CY) which substantially
corresponds to the mechanical load (M.sub.X, M.sub.Y) exerted on the
gradient magnet system. As a result, the actuator system exerts a
mechanical reaction load (M.sub.RX, M.sub.RY) on the gradient magnet
system which has the same magnitude as but is oppositely directed to the
mechanical load (M.sub.X, M.sub.Y) exerted on the gradient magnet system,
so that vibrations of the gradient magnet system are effectively limited.