Methods for determining cardiovascular information for a patient include receiving patient-specific data regarding a geometry of the patient's vasculature； creating an anatomic model representing at least a portion of the patient's vasculature based on the patient-specific data； and creating a computational model of a blood flow characteristic based on the anatomic model. The method also includes identifying one or more of an uncertain parameter, an uncertain clinical variable, and an uncertain geometry； modifying a probability model based on one or more of the identified uncertain parameter, uncertain clinical variable, or uncertain geometry； determining a blood flow characteristic within the patient's vasculature based on the anatomic model and the computational model； and calculating, based on the probability model and the determined blood flow characteristic, a sensitivity of the determined fractional flow reserve to one or more of the identified uncertain parameter, uncertain clinical variable, or uncertain geometry.
