Reconstructing 3-D Blood Vessel Shapes from Multiple X-Ray Images

Angiography is a method used by radiologists to examine the structure and health of blood vessels. The method consists of injecting an x-ray opaque contrast agent into the bloodstream, and taking one or more x-ray images of the vessel. Although these images are clear and have high resolution, they individually show structures in only two-dimensions. The goal of our work is to automatically reconstruct the threedimensional structure of a blood vessel using a small number of angiogram images taken from different angles. Among the types of information about blood vessels that are useful to physicians, the most important for diagnostic purposes is a measure of the cross-sectional area of the vessel at every location along its length. This information reveals constrictions caused by blood clots, cholesterol build-ups, or injuries. Treatment of these conditions may involve inserting a catheter, with a small video camera and scraping tool mounted at its tip, into the vessel to remove the obstruction. A computer can aid in planning this surgery by simulating what the tip of the catheter would encounter in the vessel, and by computing how far the catheter must be inserted to begin repair. This paper presents an algorithm which performs the three-dimensional reconstruction task. Each section of the paper will examine one of the main steps of the algorithm: detecting vessels in single images, finding the positions of the vessels in three dimensions, and finally performing diameter measurements. The paper concludes with some reconstruction results.