A vessel segmentation method comprising: acquiring a three-dimensional image of a blood vessel, the image comprising slices each of which comprises at least one cross section of the blood vessel, wherein the blood vessel comprises a contrast medium; acquiring a reference threshold value from a database, the reference threshold being set with respect to the intensity of the contrast medium injected into a blood vessel in an image, or calculating a reference threshold value based on intensity characteristics of the contrast medium, wherein the intensity characteristics comprises a mean intensity of the contrast medium in a region of the blood vessel extracted from the acquired image using a single threshold value, or a maximum intensity of the contrast medium in the region, or a minimum intensity of the contrast medium in the region, or a variation in the intensity of the contrast medium in the region, or any combination thereof; determining the intensity of the contrast medium in each of the cross sections of the blood vessel based on modeling data, wherein the modeling data is acquired from a database and models contrast medium flow through a vessel tree to which the blood vessel belongs, said modeling data comprising attenuation characteristics of the contrast medium and, optionally, a cardiac cycle-dependent inequality characteristic of the contrast medium, wherein the attenuation characteristics define the attenuation of contrast medium based on a number of vessel tree nodes passed through by the contrast medium and, optionally, also based on at least one of travelled distance or elapsed time, and wherein the cardiac cycle-dependent inequality characteristic reflects the intensity changes of the contrast medium based on the cardiac cycle; setting a threshold value for each of the cross sections based on the reference threshold value and the determined intensity of the contrast medium in each of the cross sections; and performing vessel segmentation based on the image and the set threshold value for each of the cross sections, wherein vessel segmentation is performed such that different thresholds are used for different cross sections in accordance with the modeling of contrast medium flow in the vessel tree; and wherein the modeling data comprises a node-dependent attenuation characteristic relative to an attenuation of the intensity due to a difference between a total size of cross section of branches splitting-off from a stem of a blood vessel and a size of the cross section of the stem. acquiring a three-dimensional image of a blood vessel, the image comprising slices each of which comprises at least one cross section of the blood vessel, wherein the blood vessel comprises a contrast medium; acquiring a reference threshold value from a database, the reference threshold being set with respect to the intensity of the contrast medium injected into a blood vessel in an image, or calculating a reference threshold value based on intensity characteristics of the contrast medium, wherein the intensity characteristics comprises a mean intensity of the contrast medium in a region of the blood vessel extracted from the acquired image using a single threshold value, or a maximum intensity of the contrast medium in the region, or a minimum intensity of the contrast medium in the region, or a variation in the intensity of the contrast medium in the region, or any combination thereof; determining the intensity of the contrast medium in each of the cross sections of the blood vessel based on modeling data, wherein the modeling data is acquired from a database and models contrast medium flow through a vessel tree to which the blood vessel belongs, said modeling data comprising attenuation characteristics of the contrast medium and, optionally, a cardiac cycle-dependent inequality characteristic of the contrast medium, wherein the attenuation characteristics define the attenuation of contrast medium based on a number of vessel tree nodes passed through by the contrast medium and, optionally, also based on at least one of travelled distance or elapsed time, and wherein the cardiac cycle-dependent inequality characteristic reflects the intensity changes of the contrast medium based on the cardiac cycle; setting a threshold value for each of the cross sections based on the reference threshold value and the determined intensity of the contrast medium in each of the cross sections; and performing vessel segmentation based on the image and the set threshold value for each of the cross sections, wherein vessel segmentation is performed such that different thresholds are used for different cross sections in accordance with the modeling of contrast medium flow in the vessel tree; and wherein the modeling data comprises a node-dependent attenuation characteristic relative to an attenuation of the intensity due to a difference between a total size of cross section of branches splitting-off from a stem of a blood vessel and a size of the cross section of the stem.