PASSIVE SHIELD FOR MAGNETIC RESONANCE IMAGING GRADIENT COILS

An MRI system including a main magnet defining a volume, an imaging region disposed within the volume. The main magnet is configured to produce a uniform main magnetic field within the volume, wherein the uniform magnetic field is oriented along a patient axis. The system includes a gradient magnetic coil assembly disposed within the volume and configured to generate a spatially varying magnetic field across the imaging region. The gradient magnetic coil assembly includes a first coil configured to generate a magnetic field in a first axis, a second coil configured to generate a magnetic field in a second axis, and a third coil configured to generate a magnetic field in the patient axis. The system also includes a passive gradient shield disposed between the main magnet and primary gradient magnetic coil assembly, the passive gradient shield can include a continuous cylindrical layer of high permeability, low electrical conductivity material.