Expansion of the clinical application of optical coherence tomography to percutaneous coronary intervention and assessment of the instability of coronary atherosclerosis.

seen because the very high resolution of OCT restricts the depth of penetration of the light beam through blood and tissue (to 1–3 mm), resulting in incomplete reflection from the deeper arterial layers.3 Moreover, a necrotic core imaged by OCT is a signal-poor region within an atherosclerotic plaque, with poorly delineated borders, a fast OCT signal drop-off, and little or no OCT signal backscattering, within a lesion that is covered by a fibrous cap. Thus, because light does not penetrate well through the necrotic core, especially in large vessels, it is generally agreed that OCT is not capable of measuring the thickness, area, or volume of the necrotic core and thus the plaque burden in large vessels, when the external elastic membrane cannot be identified. There are a number of compelling pieces of evidence that arterial outward remodeling (positive remodeling) is associated with vulnerability in the coronary artery. Previous IVUS ptical coherence tomography (OCT) is an innovative intravascular imaging tool that can be used to examine coronary atherosclerotic lesions at a resolution (10–15 μm) that far exceeds that of existing methods such as intravascular ultrasonography (IVUS), by an order of magnitude. In the research field, on account of its superior resolution, OCT has been used for qualitative assessment of vulnerable plaque characterized by thin-cap fibroatheroma;1,2 such plaque is the precursor of the ruptured thrombotic plaque, plaque containing calcium nodules, and plaque erosion.