Coronary CT angiography in the quantitative assessment of coronary plaques

Abstract

Coronary computed tomography angiography (CCTA) has been recently evaluated for its ability to assess coronary plaque characteristics, including plaque composition. Identification of the relationship between plaque composition by CCTA and patient clinical presentations may provide insight into the pathophysiology of coronary artery plaque, thus assisting identification of vulnerable plaques which are associated with the development of acute coronary syndrome. CCTA-generated 3D visualizations allow evaluation of both coronary lesions and lumen changes, which are considered to enhance the diagnostic performance of CCTA. The purpose of this review is to discuss the recent developments that have occurred in the field of CCTA with regard to its diagnostic accuracy in the quantitative assessment of coronary plaques, with a focus on the characterization of plaque components and identification of vulnerable plaques.

Figure 1

64-slice coronary CT angiography (CCTA) in a 57-year-old man with non-ST elevation myocardial infarction. (a) CCTA image of multiplanar reconstruction of left anterior descending artery (LAD) showing multiple black low-density areas (white arrows) within the plaque. (b) Visualization of the LAD stenosis showing positive remodelling and presence of low-density plaque (<30 Hounsfield units) in the middle of the plaque (black area, white circle). Reprint with permission from [24].

Figure 2

Example of lesion with positive remodelling on 320-row CT angiography and corresponding findings on virtual histologic intravascular ultrasound image. Curved multiplanar reconstruction of left anterior descending coronary artery showing a large plaque in the proximal segment of the vessel (a). The diameter of the vessel at the plaque site (arrow) is larger compared to the diameter at the reference sections (1, 2), indicating the presence of positive remodeling. Corresponding longitudinal (b) and cross-sectional (c) virtual histologic intravascular ultrasound images demonstrate an outward-remodeled lesion, with a large plaque burden (69%) and a large amount of necrotic core (19%) (red areas), corresponding to a thin-capped fibroatheroma lesion. Reprint with permission from [25].

Figure 3

Late fibroatheroma as classified by histology (a). Note the large necrotic core (∗) in the center of the plaque, which correlates with the hypodense center of the plaque (∗) in CT (b). The core is surrounded by prominent fibrotic tissue (open arrows), which appears as a hyperdense ring around the core in CT. Thus the plaque has a ring-like appearance in coronary CT angiography which was coined as napkin-ring sign. Additionally neovascularization is present within the plaque (closed arrow). Reprint with permission from [26].

Figure 4

Virtual intravascular endoscopy visualization of normal coronary artery, (a) right coronary artery and (b) left coronary artery.

Figure 5

Virtual intravascular endoscopy (VIE) visualization of mixed and calcified plaques in a 75-year-old male with coronary artery disease. (a) Curved planar reformation shows mixed plaque (short arrow) and calcified plaques (long arrows) in the proximal segment of left anterior descending coronary artery (LAD). (b) Close VIE view of the mixed plaque. (c) VIE view of the calcified plaque at LAD with significant lumen stenosis. (d) Orthogonal views help to confirm the intraluminal plaque position of the calcified plaque.

Figure 6

Virtual intravascular endoscopy (VIE) visualization of noncalcified plaque in a 42-year-old male with suspected coronary artery disease. (a) Curved planar reformation shows a noncalcified plaque at the proximal segment of right coronary artery (arrows). (b) and (c) VIE views of the plaque demonstrate smooth intraluminal appearance with significant stenosis.

Figure 7

Virtual intravascular endoscopy (VIE) visualization of mixed plaque in a 56-year-old male with coronary artery disease. (a) Curved planar reformation shows mixed plaques at the proximal segment of left anterior descending artery (LAD). Corresponding VIE images (b) and (c) show that the irregular intraluminal appearance is due to presence of different plaque components within the plaque.

Figure 8

Virtual intravascular endoscopy (VIE) appearance of extensively calcified plaque in a 52-year-old man with coronary artery disease. (a) Curved planar reformation shows significant stenosis of left anterior descending coronary artery due to presence of plaques with heavy calcification (arrows). (b) VIE shows irregular intraluminal changes due to different compositions within the plaques (arrows).