Patent ID: 8343101

Claim:
A medical fluid injector for use in an MRI procedure, comprising: a substantially non-ferrous and substantially non-magnetic fluid drive responsive to pressure of a working fluid to impart a sequence of forces to drive a delivery device to flow medical fluid, wherein the fluid drive comprises a piston disposed in a cylinder, a rod coupled to the piston, and a rotary ratchet coupled to the rod, and the fluid drive is configured to not interfere with magnetic resonance imaging, wherein the rotary ratchet is configured to sequentially engage teeth of a gear in response to oscillating motion of the piston in the cylinder, wherein the rotary ratchet comprises a first arm to sequentially engage the teeth of the gear, and wherein the rotary ratchet comprises a second arm to sequentially engage the teeth of the gear at a location that is spaced from where the first arm sequentially engages the teeth of the gear.