Patent ID: 7167004

Claim:
An MRI system comprising: a magnet assembly configured for generating a stationary magnetic field, the magnet assembly comprising: first and second substantially planar coil assemblies, each coil assembly comprising at least two drive coils; each drive coil in the first coil assembly, forming a respective pair of drive coils with a corresponding drive coil in the second coil assembly, each drive coil of each pair of drive coils being substantially planar and of a substantially same size and shape as the other of the respective pair, said drive coils in each pair of drive coils being substantially parallel to one another and substantially parallel to an intermediate reference plane, and being disposed approximately equidistant from, and symmetrically with respect to, the intermediate reference plane; wherein; each drive coil of each pair of drive coils is arranged in order to enable a current to flow therethrough, the current through a first drive coil of each respective pair being in an opposite sense to the current through a second drive coil of said respective pair, whereby, in each respective pair of drive coils, a first section of the first drive coil and a corresponding first section of the second drive coil generate a primary magnetic field extending within the intermediate reference plane; and in each respective pair of drive coils, a second section of the first drive coil, opposite to the first section of the first drive coil, and a corresponding second section of the second drive coil, opposite to the first section of the second drive coil constitute respective return paths of the first and second drive coils in said respective pair, and are disposed at a sufficient distance from the first sections of the drive coils that magnetic fields generated by the second sections do not substantially adversely affect the homogeneity of the primary magnetic field generated by the first sections.