Computed Tomography Coronary Angiography
Stephan Achenbach, MD, FESC, FACCa,*
Department of Cardiology, University of Erlangen–Nürnberg, Erlangen, Germany
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Figure 1 Typical dataset as acquired by coronary computed tomography angiography (CTA) after intravenous injection of contrast agent (here: dual-source CT with a temporal resolution of 83 ms). (A) Transaxial image (0.75-mm reconstructed slice thickness) at the level of the proximal left anterior descending coronary artery. Cross sections of the proximal left anterior descending coronary artery (arrow) and left circumflex coronary artery (arrowhead) are visible. (B) Transaxial image at the level of the right coronary artery ostium. Smaller arrow: right coronary artery; larger arrow: left anterior descending coronary artery; arrowhead: left circumflex coronary artery. (C) Transaxial image at the midventricular level. Smaller arrow: right coronary artery; larger arrow: left anterior descending coronary artery; arrowhead: left circumflex coronary artery. (D) Maximum intensity projections (here: 5-mm thickness in axial orientation) can be used to visualize longer segments of the coronary arteries and the relationship of main and side branches. Here, the left main and proximal left anterior descending (arrow) as well as left circumflex coronary artery (arrowhead) are displayed. (E) Another maximum intensity projection (8-mm thickness) in a double-oblique plane that parallels the right interventricular groove is used to display the entire course of the right coronary artery (arrows). (F) Curved multiplanar reconstruction (0.75-mm thickness) was used to visualize the right coronary artery (arrows). (G) Three-dimensional display of the heart and coronary arteries. Smaller arrow: right coronary artery; larger arrow: left anterior descending coronary artery; arrowhead: left circumflex coronary artery.
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Figure 2 Systolic (A) and diastolic (B) reconstruction of a "short axis" reformat to analyze left ventricular function. Such information can be obtained as a byproduct of coronary computed tomography angiography from the same dataset using largely automated processing tools.
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Figure 3 Artifacts typically encountered in computed tomography coronary angiography. (A) An obvious motion artifact is present at the level of the mid-right coronary artery. A round cross section of the right coronary artery would be expected. Because of motion, the contour of the right coronary artery is blurred (larger arrows). In addition, on both sides of a small side branch, areas of very low computed tomography attenuation can be noted (smaller arrows). These artifacts also are caused by motion and typically are found adjacent to high-contrast structures (e.g., contrast-enhanced coronary arteries). (B) Severe coronary calcification in the proximal left anterior descending coronary artery (arrows). Calcifications of this extent can in some cases render the datasets unevaluable concerning the presence of coronary artery stenoses. (C) In some cases, the occurrence of a motion artifact is more subtle. The figure displays transaxial images at the level of the mid-right coronary artery, just distal to the ostium of a right ventricular side branch (arrowhead). On the left, the image was reconstructed at 70% of the cardiac cycle. A slight motion artifact is present (smaller arrow), which blurs the contour of a calcified plaque in the arterial wall (larger arrow) and also causes a low-density structure, which might be mistaken for noncalcified plaque components. On the right, the same image was reconstructed at 65% of the cardiac cycle. No motion artifact is present. The plaque is practically entirely calcified.
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Figure 4 Shown is a patient with a high-grade stenosis of the left anterior descending coronary artery. (A) Transaxial computed tomography image (0.75-mm slice thickness) showing the stenosis, which involves the left anterior descending coronary artery and the relatively large diagonal branch. (B) In a 5-mm thick maximum intensity projection (transaxial orientation), the stenosis is more readily seen (arrow). Again, it can be seen that the stenosis involves the ostium of the left anterior descending coronary artery and a large diagnonal branch in this bifurcation. (C) Curved multiplanar reconstruction of the left anterior descending coronary artery (larger arrow) shows the stenosis and the involvement of the side branch (smaller arrow). (D) Three-dimensional reconstruction ("volume rendering technique"). The stenosis of the left anterior descending coronary artery proximal to the bifurcation is clearly visible (arrow). However, the limited spatial resolution of the 3-dimensional reconstruction fails to demonstrate the presence of ostial stenoses of the 2 bifurcation branches. (E) Invasive coronary angiogram.
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Figure 5 Computed tomography angiography in a patient with 3 venous coronary artery bypass grafts. (A) Transaxial cross section showing the aortic anastomosis and a cross section of the mid-segments of the venous graft to the left anterior descending coronary artery (arrows). In addition, a cross section of the left circumflex graft is seen (arrowhead). (B) Transaxial 5-mm thick maximum intensity projection showing the aortic anastomosis of the right coronary artery bypass graft (double arrows). In addition, a cross section of the left anterior descending graft (larger arrow) and of the left circumflex graft (arrowhead) are visible. The proximal left coronary artery is seen, with a high-grade stenosis of the left main coronary artery proximal to the bifurcation (smaller arrow). The coronary arteries are of narrow lumen and have substantial calcification. (C) Curved multiplanar reconstruction of the venous graft to the right coronary artery (arrows). The double arrows indicate the anastomosis to the distal right coronary artery. (D) Three-dimensional reconstruction showing bypass graft to left anterior descending (larger arrow), to left circumflex (arrowhead), and to right coronary artery (smaller arrow).
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Figure 6 Imaging of coronary artery stents. (A) A stent with a diameter of 3.5 mm in a distal left main coronary artery, immediately proximal to the bifurcation, is assessable by coronary computed tomography angiography and shows absence of in-stent restenosis (arrow). (B) A stent with a diameter of 3.5 mm in a right coronary artery shows artifacts within the stent lumen and cannot be assessed by computed tomography.
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Figure 7 Imaging of coronary atherosclerotic plaque. (A) Small, partly calcified coronary atherosclerotic plaque in the very proximal segment of the left anterior descending coronary artery (arrow). (B) In a patient with severe coronary atherosclerosis, calcified (smaller arrow) and noncalcified plaque (larger arrow) are visible in the mid-section of the left anterior descending coronary artery.
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