1. A method for producing an index indicative of vascular disease in a subject with an ultrasound imaging system, the steps comprising: a) administering a contrast agent to the subject; b) acquiring, with the ultrasound imaging system, a series of image frames from the subject during a passage of the contrast agent through a tissue of interest in the subject; c) calculating, from the series of image frames, a perfusion rate in the tissue of interest; d) calculating, from the series of image frames, information indicative of a deformation of the tissue of interest; and e) producing an index indicative of vascular disease using the calculated perfusion rate and calculated information indicative of the deformation of the tissue of interest.