A method of determining at least one parameter for an imaging procedure including the injection of a contrast enhancement fluid which includes a contrast enhancing agent, includes: substituting into a model discrete point data determined from at least one contrast time enhancement curve measured using an imaging system for a first region of interest resulting from injection of a bolus of the contrast enhancement fluid. In several embodiments, a sufficient number of data points can be substituted into the model to determine values for physiological variables in the model. The variables can, for example, be related to cardiopulmonary function. At least one data point from at least a second contrast time enhancement curve for a second region of interest measured using the imaging system can also substituted into the model.