Coronary CT angiography in coronary artery disease: correlation between virtual intravascular endoscopic appearances and left bifurcation angulation and coronary plaques

Abstract

The aim of this study is to investigate the relationship between intraluminal appearances of coronary plaques and left coronary bifurcation angle and plaque components using coronary CT virtual intravascular endoscopy (VIE). Fifty patients suspected of coronary artery disease undergoing coronary CT angiography were included in the study. The left bifurcation angle in patients with diseased left coronary artery which was measured as 94.3° ± 16.5 is significantly larger than that in patients with normal left coronary artery, which was measured as 76.5° ± 15.9 (P < 0.001). Irregular VIE appearances were found in 10 out of 11 patients with mixed plaques in the left anterior descending (LAD) and left circumflex (LCx), while, in 29 patients with calcified plaques in the LAD and LCx, irregular VIE appearances were only noticed in 5 patients. Using 80° as a cut-off value to determine coronary artery disease, smooth VIE appearances were found in 95% of patients (18/19) with left bifurcation angle of less than 80°, while irregular VIE appearances were observed in nearly 50% of patients (15/31) with left bifurcation angle of more than 80°. This preliminary study shows that VIE appearances of the coronary lumen are directly related to the types of plaques.

Figure 1

Curved planar reformatted image (a) shows that the left bifurcation angle is measured as 40.3° in a 54-year-old woman with a normal left coronary artery. 3D volume rendering (b) shows that the left bifurcation angle is measured as 104.5° in 71-year-old man with left coronary disease.

Figure 2

Visualization of anatomic structures on virtual intravascular endoscopy (VIE) image. A VIE image is generated to look at the ostium of left coronary artery (top left), and corresponding orthogonal views (axial on top right, coronal and sagittal views on the bottom right and left, resp.) confirm the exact location of the structure. The blue box indicates the viewing position placed on the VIE image.

Figure 3

Maximum-intensity projection shows that calcified plaques are present at the proximal segment of left anterior descending (long arrow) and midsegment of left circumflex (short arrow) (a). Curved planar reformation shows a noncalcified plaque at the proximal segment of right coronary artery ((b) arrows). 2D axial image demonstrates a mixed plaque at the proximal segment of left anterior descending (c), with short arrow referring to the calcified component and long arrow to the noncalcified component within the plaque.

Figure 4

Curved planar reformatted images show that the left bifurcation angle is measured as 88.5° in a 58-year-old woman with extensive calcified plaques in the left anterior descending and left circumflex (a), while, in another 46-year-old man, the angle is measured as 71.3° with normal left coronary artery (b).

Figure 5

Measurement of the left coronary artery diameter is shown on 2D axial image in a 52-year-old man with significant coronary stenosis. The left anterior descending (a) and left circumflex branches (b) are measured as 6.1 mm and 3.7 mm in the proximal segments due to presence of extensively calcified plaques at both artery branches.

Figure 6

VIE visualization of normal coronary artery wall. Smooth intraluminal appearance is observed with clear demonstration of the coronary ostia of left anterior descending (LAD) and left circumflex (LCx).

Figure 7

VIE appearance of calcified plaques. An eccentric calcified plaque is formed in the left anterior descending on a 2D axial image ((a) arrows), and corresponding VIE shows the smooth protruding appearance in the superior lumen of left anterior descending ((b) long arrows). The plaque is close to the ostium of left circumflex (LCx) and covers the other ostia of left coronary side branches (short arrows). A concentric plaque is present in the left anterior descending in another patient on 2D axial images ((c) arrows), and corresponding VIE shows intraluminal smooth appearance around the coronary lumen ((d) arrows).

Figure 8

A heavily calcified plaque is present at the proximal segment of left anterior descending ((a) arrows). VIE shows irregular intraluminal appearance ((b) arrows).

Figure 9

VIE appearance of noncalcified plaques. A noncalcified plaque is found in the midsegment of left anterior descending on a curved planar reformatted image ((a) arrow), and corresponding VIE confirms the smooth protruding appearance arising from the inferior lumen of the coronary artery wall ((b) arrows).

Figure 10

A series of 2D axial images show mixed plaques with the majority of the components representing noncalcified plaque at the proximal segment of left anterior descending ((a) arrows). Corresponding VIE shows irregular lumen change due to different plaque components (b).

Figure 11

VIE appearance of mixed plaques within a coronary segment. Extensive calcification and noncalcified component are found in the left anterior descending representing the mixed plaques on a curved planar reformatted image ((a) arrows). VIE shows irregular intraluminal changes due to different compositions within the plaques ((b) arrows).

Figure 12

VIE appearance of extensively calcified plaques. More than 50% lumen stenosis is noticed in the left anterior descending on a curved planar reformatted image (a). VIE reveals the significant stenosis with plaque surrounding the coronary wall of left anterior descending ostium with irregular intraluminal appearances ((b) arrows).

Figure 13

2D axial images show the extensively calcified plaques in the left anterior descending ((a) arrows). VIE demonstrates irregular intraluminal changes at the proximal segment ((b) arrow) and midsegment of left anterior descending ((c) arrows) with significant lumen stenosis.

Figure 14

Extensively calcified plaques on a 2D axial image show more than 90% stenosis (due to blooming artefacts) in the left anterior descending (a). VIE confirms that only 60% lumen stenosis with smooth intraluminal appearance ((b) arrows).