3-D coronary angiography: improving visualization strategy for coronary interventions

Summary

Given the 3-D character of the coronary artery tree, it is expected that any projection will foreshorten a variety of segments. The visual perception provided by such a projection shows a variety of arterial segments with a degree of foreshortening that may or may not be appreciated. Due to the problem of vessel overlap and foreshortening, multiple projections are necessary to adequately evaluate the coronary arterial tree with arteriography in the form of coronary fluoroscopy or angiograms. The elimination or at least minimization of foreshortening and overlap is a prerequisite for an accurate quantitative coronary analysis such as determination of intra-coronary lengths in a 2-D display. Hence, the patient might receive additional radiation and contrast material during diagnostic and interventional procedures. This traditional trial-and-error method provides views in which overlapping and foreshortening are minimized, but only in terms of the subjective experience-based judgment of the angiographer. A method has been developed for on-line 3-D reconstruction of the coronary arterial trees based on two views acquired from routine angiograms at arbitrary orientation using a single-plane or biplane imaging system. Based on any coronary stenosis, a plane of gantry angulations minimizing the foreshortening of arterial segment is calculated yielding multiple computer-generated projection images among which a set of views with minimal vessel overlap are chosen. With the proposed technique, the spatial relationships and 3-D morphological structures of arteries can be clearly identified which are not easily achieved by other modalities such as interventional ultrasound or magnetic resonance imaging. A computer simulation confirmed the accuracy of 3-D reconstruction to within 2.1% error by use of a pair of actual angiograms of intra-coronary guide wire. The length of the wire is 105 mm with 8 markers of 15 mm inter-distance. More than 120 cases of coronary arterial trees have been completed for 3-D reconstruction including left coronary artery trees, right coronary artery trees, and bypass grafts among which more than 40 cases were performed in-room of our cardiac catheterization laboratory. With this 3-D coronary processing tool, assessment of lesion length and diameter narrowing can be optimized in both interventional cases and studies of progression and regression.