A computer-implemented method for assessing a vascular function of a cardiac vasculature having a stenotic segment, the method comprising: acquiring a first medical image of the cardiac vasculature recorded at a first projection angle and a second medical image of the cardiac vasculature recorded at a second projection angle; determining a first vascular model modeling the cardiac vasculature recorded in the medical images by determining image centerlines for the first and second medical images through branches of the cardiac vasculature, identifying homologous branches among the image centerlines for the first and second medical images by orientating the image centerlines of the first and second medical images with respect to each other based on a difference between the first and second projection angles, mapping the image centerlines of the first and second medical images of the identified homologous branches to a three-dimensional coordinate system, identifying connected branches using route tracing beginning at ends of the image centerlines for the first and second medical images for each of the identified branches that are homologous among the first and second medical images, and creating the first vascular model using the determined image centerlines, the identified homologous branches, the mapped image centerlines to the three-dimensional coordinate system, and the identified connected branches of the cardiac vasculature; determining a first value for a characteristic of flow through the stenotic segment in the first vascular model; generating a second vascular model from the first vascular model, with at least one modification to the second vascular model which produces a difference in the characteristic of flow for the second vascular model; determining a second value for the characteristic of flow through the stenotic segment for the second vascular model; and calculating a flow index quantifying the vascular function of the cardiac vasculature modeled by the first vascular model, wherein the calculating is based on comparing first and second values for the characteristic of flow in said first and said second vascular models. acquiring a first medical image of the cardiac vasculature recorded at a first projection angle and a second medical image of the cardiac vasculature recorded at a second projection angle; determining a first vascular model modeling the cardiac vasculature recorded in the medical images by determining image centerlines for the first and second medical images through branches of the cardiac vasculature, identifying homologous branches among the image centerlines for the first and second medical images by orientating the image centerlines of the first and second medical images with respect to each other based on a difference between the first and second projection angles, mapping the image centerlines of the first and second medical images of the identified homologous branches to a three-dimensional coordinate system, identifying connected branches using route tracing beginning at ends of the image centerlines for the first and second medical images for each of the identified branches that are homologous among the first and second medical images, and creating the first vascular model using the determined image centerlines, the identified homologous branches, the mapped image centerlines to the three-dimensional coordinate system, and the identified connected branches of the cardiac vasculature; determining image centerlines for the first and second medical images through branches of the cardiac vasculature, identifying homologous branches among the image centerlines for the first and second medical images by orientating the image centerlines of the first and second medical images with respect to each other based on a difference between the first and second projection angles, mapping the image centerlines of the first and second medical images of the identified homologous branches to a three-dimensional coordinate system, identifying connected branches using route tracing beginning at ends of the image centerlines for the first and second medical images for each of the identified branches that are homologous among the first and second medical images, and creating the first vascular model using the determined image centerlines, the identified homologous branches, the mapped image centerlines to the three-dimensional coordinate system, and the identified connected branches of the cardiac vasculature; determining a first value for a characteristic of flow through the stenotic segment in the first vascular model; generating a second vascular model from the first vascular model, with at least one modification to the second vascular model which produces a difference in the characteristic of flow for the second vascular model; determining a second value for the characteristic of flow through the stenotic segment for the second vascular model; and calculating a flow index quantifying the vascular function of the cardiac vasculature modeled by the first vascular model, wherein the calculating is based on comparing first and second values for the characteristic of flow in said first and said second vascular models.