Abstract: A diastole-based hemodynamic index, such as instantaneous wave-free ratio (IWFR), may be calculated noninvasively for a patient by receiving image data respective of an anatomical region of the patient, creating an electronic model of the anatomical region, creating one or more boundary conditions model value sets representative of flow conditions during diastole, calculating one or more pressure drops at a location in the anatomical region, and determining, based on the calculated pressure drop(s) and based on a reference pressure, a hemodynamic index value, such as IWFR, for the location.