System and method to improve performance of asymmetrical gradient coils by allowing a uniform offset field

An asymmetric electromagnet system for generating a magnetic field in an imaging region with an imaging isocentre, the imaging region being asymmetrically positioned within a gradient coil bore inside a magnetic resonance imaging (MRI) system. The electromagnet assembly comprises: an asymmetric gradient coil to generate a gradient field in the imaging region, at least one gradient axis having the gradient field with a constant offset component such that the position at which the gradient field passes through zero is offset with respect to the imaging isocentre of the imaging region. The gradient may be a z gradient. The offset may be between 7 and 15 centimetres. A radiofrequency (RF) compensator may be used to modulate a frequency of an RF transmitter and receiver to counteract the change in frequency caused by the gradient offset.