Abstract: Methods and apparatus are provided for measuring movement of an elongated instrument. The apparatus including a guide adapted to receive the elongated instrument and a sensor module that includes an optical image sensor or an optical rotary encoder to sense the received elongated instrument moving within the guide.

Abstract: A delivery device for a biliary stent constructed of thermoplastic material with ridges and valleys formed along the outer surface of the stent that provide a helical, thread-like configuration. The delivery device comprises an external surface that is selectively expandable to engage an interior surface of the tubular stent. Additionally the exterior surface may include ridges and valleys that coincide with ridges and valleys defined by the helical thread extending through the stent in order to provide a more secure engagement with the stent during delivery.