A computer-implemented method of segmenting a vascular image into vascular paths for defining paths of blood flow, the method comprising: receiving, in a processor , the vascular image; defining, via the processor , first and second targeted vascular path end regions within the vascular image; segmenting, via the processor , the vascular image to identify the positions of vascular portions in the vascular image; automatically generating, via the processor , a plurality of vascular paths from the identified vascular portions, each vascular path defining a potential vascular path that extends between the first and second targeted vascular path end regions; predetermining, via the processor an order of selection for the vascular paths by ranking the vascular paths, in an order, based on assessment of a likelihood that each vascular path corresponds to an actual vascular path of blood flow in blood vessels imaged in the vascular image by applying a cost function that assigns numerical costs to one or more features related to the vascular paths; displaying, via the processor , the plurality of vascular paths registered to the vascular image as suggested path options for selection by a user via a user interface , each of the displayed vascular paths including the first and second targeted vascular path end regions; and receiving, in the processor , the vascular path which the user has selected for defining a path of blood flow; adjusting, via the processor, costs assigned to vascular paths for other targeted vascular path end regions based on the selection of the vascular path; and adjusting, removing, or adding, via the processor vascular paths for other targeted vascular path end regions that are within the vascular image based on the respective adjusted cost of the vascular paths for other targeted vascular path end regions. receiving, in a processor , the vascular image; defining, via the processor , first and second targeted vascular path end regions within the vascular image; segmenting, via the processor , the vascular image to identify the positions of vascular portions in the vascular image; automatically generating, via the processor , a plurality of vascular paths from the identified vascular portions, each vascular path defining a potential vascular path that extends between the first and second targeted vascular path end regions; predetermining, via the processor an order of selection for the vascular paths by ranking the vascular paths, in an order, based on assessment of a likelihood that each vascular path corresponds to an actual vascular path of blood flow in blood vessels imaged in the vascular image by applying a cost function that assigns numerical costs to one or more features related to the vascular paths; displaying, via the processor , the plurality of vascular paths registered to the vascular image as suggested path options for selection by a user via a user interface , each of the displayed vascular paths including the first and second targeted vascular path end regions; and receiving, in the processor , the vascular path which the user has selected for defining a path of blood flow; adjusting, via the processor, costs assigned to vascular paths for other targeted vascular path end regions based on the selection of the vascular path; and adjusting, removing, or adding, via the processor vascular paths for other targeted vascular path end regions that are within the vascular image based on the respective adjusted cost of the vascular paths for other targeted vascular path end regions. <EOS>