The Role of Intracoronary Plaque Imaging with Intravascular Ultrasound, Optical Coherence Tomography, and Near-Infrared Spectroscopy in Patients with Coronary Artery Disease

The development of multiple diagnostic intracoronary imaging modalities has increased our understanding of coronary atherosclerotic disease. These imaging modalities, intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near-infrared spectroscopy (NIRS), have provided a method to study plaques and introduced the concept of plaque vulnerability. They are being increasingly used for percutaneous coronary intervention (PCI) optimization and are invaluable tools in research studying the pathophysiology of acute coronary syndrome (ACS), in-stent thrombosis and in-stent restenosis. IVUS has the ability to visualize the intracoronary lumen and the vessel wall and can be used to detect early atherosclerotic disease even in the setting of positive arterial remodeling. Studies supporting the use of IVUS to optimize stent deployment and apposition have shown a significant reduction in cardiovascular events. OCT provides even higher resolution imaging and near microscopic detail of plaques, restenoses, and thromboses; thus, it can identify the etiology of ACS. Ongoing trials are evaluating the role of OCT in PCI and using OCT to study stent endothelialization and neointimal proliferation. NIRS is a modality capable of localizing and quantifying lipid core burden. It is usually combined with IVUS and is used to characterize plaque composition. The benefits of NIRS in the setting of ACS have been limited to case reports and series. The utilization of all these intracoronary imaging modalities will continue to expand as their indications for clinical use and research grow. Studies to support their use for PCI optimization resulting in improved outcomes with potential to prevent downstream events are ongoing.