A magnet resonance imaging system is described having an open magnet
structure that provides a remote region of background field homogeneity
for imaging that is open and accessible. The system includes spatial
encoding gradient coils and a rf coil. The open magnet structure has an
planar active shimming coil array that provides a remote region of
enhanced field homogeneity with open geometry for easy accessibility to a
patient. Preferably, the active planar shimming coil array has one or more
pair of current loops arranged and constructed in a plane separating the
open magnet structure from the remote region, a first loop having current
in a first direction to provide a magnetic flux (i.e., magnetization
vector) away from the plane and a second loop having current in the
opposite direction to provide a magnetic flux (i.e., magnetization vector)
toward the plane.
