Abstract: A diagnostic imaging apparatus such as a magnetic resonance imaging (MRI) device includes a vacuum vessel (24) having a central helium reservoir (16) in which superconducting magnetic coil windings (10) are maintained at a superconducting temperature. The vacuum vessel defines a bore (12) within which a gradient tube assembly (30) and an RF coil (32) are received. The gradient tube assembly includes an integral tongue (66) extending from a patient end (48) thereof. A first constraint (70) retrains the gradient tube assembly in a “push-pull” arrangement in both directions along the z-axis. The constraint (70) is mounted to a patient-end of the vessel (24) at a lowermost (i.e., six o'clock) position. The constraint includes vibration isolators (94) interposed between the tongue and a saddle mount (72) to reduce vibration transmission from the gradient tube assembly to the vessel.

Abstract: The magnetic field assembly of a magnetic resonance imaging device includes an annular superconducting magnet (10) which is mounted within a toroidal vacuum vessel (24). Two cylindrical members (26, 46) define an annular gap (58). A shim set (60) for shimming the uniformity of the magnetic field is mounted in the gap (58). The shim set includes a plurality of shim trays (62), each of which defines a plurality of shim receiving pockets (64). A bottom wall (81) of each pocket is spaced from the cylindrical member (26) by side walls (76) and feet (78) to minimized heat flow. Shim tray covers (68) have flanges (90) and narrow contact surfaces (94) which are cammed against surfaces (61) of spacers (56) to press the cover on the tray and the tray feet against the cylinder (26) while minimizing heat flow through the spacers to the shims.