Methods of determining at least one parameter for an injection procedure to be performed in combination with an imaging procedure may include injecting a test bolus of a contrast enhancement fluid having a contrast enhancing agent, scanning regions of interest with an imaging system as the test bolus flows therethrough to obtain therefrom a contrast time enhancement curve for each region of interest, extracting at least one discrete data point from each of the contrast time enhancement curves such that each of the discrete data points constitutes a pair of measurements on the contrast time enhancement curve corresponding thereto, substituting into a model the discrete data points extracted from the contrast time enhancement curves to obtain an estimate of values of physiological variables, and using the estimate to determine via the model the at least one parameter for the injection procedure to be performed in combination with the imaging procedure.