The present invention relates to apparatus for automatic quantification of a part of vascular structure. It is described to provide (12) at least one first image comprising a spatial representation of a region of interest of a vascular structure, wherein the at least one first image comprises image data representative of a location of a part of a medical device. The medical device is configured to be used in a vascular treatment, and the part of the medical device is configured to be in a plurality of states associated with different phases of the vascular treatment. At least one second image comprising a spatial representation of the region of interest of the vascular structure is provided (14), wherein the at least one second image comprises image data representative of at least a part of the vascular structure in a visible and distinct manner. A location of a feature in the spatial representation of the region of interest of the vascular structure of the at least one first image is determined (18), wherein the feature is associated with the part of the medical device in one of the states associated with a phase of the vascular treatment. A transform relating at least one location in the at least one first image to a corresponding at least one location in the at least one second image is determined (20) and applied to the location of the feature in the spatial representation of the region of interest of the vascular structure of the at least one first image to provide a determined location in the spatial representation of the region of interest of the vascular structure of the at least one second image. Data is output (22) representative of the vascular structure at the determined location.La présente invention concerne un appareil permettant la quantification automatique d'une partie d'une structure vasculaire. L'invention consiste à fournir (12) au moins une première image comprenant une représentation spatiale d'une région d'intérêt d'une structure vasculaire,
