Embodiments include a system for determining patient cardiovascular information which includes at least one computer system configured to receive patient-specific data regarding a geometry of an anatomical structure of a patient； create a model representing at least a portion of the anatomical structure of the patient based on the patient-specific data； determine a first blood flow rate at at least one point of interest in the model by using relations of individual-specific anatomic data to functional estimates of blood flow characteristics generated from a plurality of individuals； modify the model； determine a second blood flow rate at a point in the modified model corresponding to the at least one point of interest by using the relations of individual-specific anatomic data to functional estimates of blood flow characteristics； and determine a fractional flow reserve value as a ratio of the second blood flow rate to the first blood flow rate.
