Click on image to view larger version.

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.