A method for processing an intravascular image including a plurality of image frames acquired during a pullback of an imaging catheter inserted into a vessel. The method includes obtaining positions of lumen borders detected in the intravascular image and positions of stent-struts detected in the intravascular image. Determining, at different positions in a range, a stent expansion value of the stent implanted in the vessel, based on the first information and the second information, wherein each image frame from image frames in which stent-struts are detected corresponds to a different position along the range. The method may also include displaying an image including positions of lumen borders and positions of the stent-struts detected and a first indicator indicating a level along the range, of the stent expansion value, with the image.
