A device for correlating trend data with respect to a patient’s weight ankle displacement can identify conditions indicative of congestive heart failure. A mask size of the second pattern group is determined such that the second pattern group secures a sufficient process margin relative to a given size and size accuracy. Additionally, by including a contrast container holder that is affixed to an injector head and holds the container near the syringe tip, the filling sequence can be accomplished without requiring the operator to hold the contrast container during the sequence.