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.