In-vivo measurement of coronary stent dimensions throughout entire vascular segments with quantitative three-dimensional intravascular ultrasound: a review

The implantation of metallic endoprostheses (i.e., stents) is a rapidly exp anding interventional technique for the catheter-based therapy of symptomat ic patients with significant coronary stenoses. But stents are frequently r adiolucent and after deployment difficult to appreciate on fluoroscopy and coronary angiograms obtained by x-ray. Intravascular ultrasound (IVUS), on the other hand, permits detailed examination of coronary stent apposition a nd expansion in vivo. Recently, automated systems for three-dimensional (3- D) reconstruction and analysis of IVUS images have been developed. The init ial experience with 3-D IVUS in coronary stenting is positive. Different te chnical approaches demonstrated superiority of 3-D IVUS in detecting both, the site of the smallest in-stent lumen cross-sectional area and sub-optima l results following stent deployment. In-addition, the restenosis process i nside stents can excellently be studied with IVUS. In-stent neointimal ingr owth can be examined with a computerized 3-D contour detection system that permits off-line detection of the neointimal leading edge and the coronary stent struts. This 3-D approach provides computerized measurement of neoint imal volume, based on a large number of IVUS images. Considering the curren t trend towards more complex coronary stenting procedures, a feasible and r eliable 3-D analysis tool for clinical on-line assessment after stent deplo yment may also be very useful.