Optical coherence tomography for evaluation of coronary stents in vivo

Coronary optical coherence tomography (OCT) is a light-based imaging modality that emits light in the near-infrared range. Compared with intravascular ultrasound, OCT has an extraordinarily high resolution (nearly tenfold higher), with an axial resolution in the range of 12-15 µm and a lateral resolution of 20-40 µm. The main drawback of OCT is its relatively low penetration power, especially into lipid-rich atherosclerotic tissue. Second-generation OCT systems, known as frequency domain OCT, are now widely available in many catheter laboratories. The hallmark of OCT is its outstanding ability to depict superficial vessel wall structures with high accuracy. In this regard, OCT was used to evaluate stent expansion and stent strut apposition both early and late following stent deployment, as well as neointimal coverage over struts at long-term follow-up. It has discriminated the differences in strut malapposition and strut neointimal coverage among different stent designs and in various strut subsets. Similarly, OCT delineated many forms of vessel wall injury following percutaneous coronary intervention, such as dissections, thrombosis and tissue protrusion between struts. Recently, OCT was used to study the biodegradation of bioresorbable vascular scaffolds. This review focuses on the role of OCT in the in vivo evaluation of coronary stents.