New Insights into the Association between Fibrinogen and Coronary Atherosclerotic Plaque Vulnerability: An Intravascular Optical Coherence Tomography Study

Figure 3

Representative optical coherence tomography (OCT) images of coronary atherosclerotic plaques with different characteristics. (a) Fibrotic plaque is characterized by a homogeneous OCT signal and high backscattering. (b) A fibroatheroma was characterized by an atherosclerotic plaque with an OCT-delineated necrotic core (formed by a signal-poor region with poorly delineated borders and little or no OCT backscattering), covered by a fibrous cap (signal-rich layer). (c) A calcific fibroatheroma was characterized by a plaque containing calcium deposits (signal-poor regions with sharply delineated borders). (d) A thin-cap fibroatheroma was characterized by a plaque with lipid content in ≥ 2 quadrants and with a fibrous cap < 65 μm. (e) Macrophage accumulation was reflected by a signal-rich punctate region in the background of an atherosclerotic plaque. Macrophages could be quantitatively classified as follows: grade 0, no macrophage; grade 1, localized macrophage accumulation; grade 2, clustered accumulation < 1 quadrant; grade 3, clustered accumulation ≥ 1 quadrant but < 3 quadrants; and grade 4, clustered accumulation ≥ 3 quadrants. (f) Plaque rupture was characterized by discontinuity of the fibrous cap with a cavity formed inside the plaque. (g) Intracoronary thrombus was characterized by a mass (diameter > 250 mm) that could be attached to the luminal surface or floating within the lumen. A red thrombus that was rich in red blood cells could be identified by high backscattering and high attenuation, while a white thrombus that was rich in platelets could be identified by homogeneous backscattering with low attenuation. (h) The vasa vasorum was characterized by voids with poor signals that were sharply delineated in multiple contiguous frames. (i) Calcified nodules were characterized by a small nodular calcification protruding from the lumen at the base of the fibrous calcified plaques with thrombus formation. (j) Acute Coronary Syndrome with Intact Fibrous Cap (ACS-IFC) was characterized by the following three conditions: (1) presence of the attached thrombus overlying an intact and visualized plaque; (2) irregularity of the luminal surface at the culprit lesion in the absence of thrombus; or (3) attenuation of the underlying plaque by thrombus that was not near a superficial lipid or calcification.

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