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Pitfalls, Artifacts, and Remedies in Multi– Detector Row CT Coronary Angiography¹

¹ From the Department of Diagnostic Radiology and Research Institute of Radiological Science (H.S.C., B.W.C., K.O.C., M.I.K., J.K.), Cardiology Division, Cardiovascular Center (D.C.), and Cardiovascular Surgery, Cardiovascular Center (K.J.Y.), Yonsei University College of Medicine, Seoul, South Korea. Received February 3, 2003; revision requested March 24 and received May 13; accepted October 1. Address correspondence to B.W.C., Department of Diagnostic Radiology, Yonsei University College of Medicine, 134 Sinchon-dong, Seodaemoon-gu, Seoul 120–752, South Korea (e-mail: bchoi@yumc.yonsei.ac.kr).

View larger version (153K): [in a new window]   Figure 1a.  Stepladder artifacts due to cardiac motion and inappropriate pitch selection. (a) Volume-rendered image shows multiple linear offsets (arrows) that resemble a stepladder, caused by a rapid heart rate (96-103 beats per minute). (b) Sagittal maximum intensity projection image shows a stepladder artifact in the mediastinum (arrowheads) but not the chest wall (arrows), an effect caused by cardiac as opposed to respiratory motion (compare with Figure 6).

View larger version (157K): [in a new window]   Figure 1b.  Stepladder artifacts due to cardiac motion and inappropriate pitch selection. (a) Volume-rendered image shows multiple linear offsets (arrows) that resemble a stepladder, caused by a rapid heart rate (96-103 beats per minute). (b) Sagittal maximum intensity projection image shows a stepladder artifact in the mediastinum (arrowheads) but not the chest wall (arrows), an effect caused by cardiac as opposed to respiratory motion (compare with Figure 6).

View larger version (159K): [in a new window]   Figure 2.  Stepladder artifact due to tachycardia. Volume-rendered image shows a severe motion-related artifact (arrows) caused by acceleration in heart rate toward the end of the breath hold.

View larger version (165K): [in a new window]   Figure 3.  Stepladder artifact due to cardiac arrhythmia. Volume-rendered image shows an isolated linear misregistration (arrow) caused by premature ventricular contraction.

View larger version (119K): [in a new window]   Figure 4a.  Minimization of cardiac motion-related blurring with an optimal reconstruction window. Axial images reconstructed from data acquired at 40% (a) and 70% (b) of the R-R interval show right coronary artery blurring (arrow), less severe in b, that is probably attributable to rapid filling of the left ventricle during early diastole. Although the right coronary artery in our study was generally best visualized at 40% of the R-R interval, in this case the optimal reconstruction window for depiction of the right coronary artery was at 70%.

View larger version (122K): [in a new window]   Figure 4b.  Minimization of cardiac motion-related blurring with an optimal reconstruction window. Axial images reconstructed from data acquired at 40% (a) and 70% (b) of the R-R interval show right coronary artery blurring (arrow), less severe in b, that is probably attributable to rapid filling of the left ventricle during early diastole. Although the right coronary artery in our study was generally best visualized at 40% of the R-R interval, in this case the optimal reconstruction window for depiction of the right coronary artery was at 70%.

View larger version (168K): [in a new window]   Figure 5a.  Minimization of stepladder artifacts with maintenance of an optimal heart rate and selection of an optimal reconstruction window. Volume-rendered images reconstructed from data acquired at 40% (a) and 70% (b) of the R-R interval, with a heart rate of 55 beats per minute, show a stepladder artifact, which is less pronounced in b. Note also the improved depiction in b of patency both in the in situ graft of the left internal mammary artery to the distal left anterior descending artery (arrowhead) and in the Y-graft (straight arrow) of a radial artery from the left internal mammary artery to the diagonal artery (curved arrow).

View larger version (167K): [in a new window]   Figure 5b.  Minimization of stepladder artifacts with maintenance of an optimal heart rate and selection of an optimal reconstruction window. Volume-rendered images reconstructed from data acquired at 40% (a) and 70% (b) of the R-R interval, with a heart rate of 55 beats per minute, show a stepladder artifact, which is less pronounced in b. Note also the improved depiction in b of patency both in the in situ graft of the left internal mammary artery to the distal left anterior descending artery (arrowhead) and in the Y-graft (straight arrow) of a radial artery from the left internal mammary artery to the diagonal artery (curved arrow).

View larger version (120K): [in a new window]   Figure 6.  Stepladder artifact due to pulmonary motion. Sagittal maximum intensity projection image shows a severe respiration-related artifact in the anterior chest wall (arrows), as well as beam hardening effects caused by surgical clips and calcifications in the sternum.

View larger version (175K): [in a new window]   Figure 7a.  Beam hardening effects caused by surgical clips. (a) Volume-rendered image from data acquired at 70% of the R-R interval shows a "blooming" artifact in which the surgical clips appear larger than their actual size. This beam hardening effect degrades depiction of the left internal mammary arterial graft (straight arrows), but not that of the right coronary artery (arrowhead) and left anterior descending artery (curved arrow). (b) Volume-rendered image from data acquired at 40% of the R-R interval is degraded by cardiac motion as well as by beam hardening effects (arrows). Arrowhead indicates the right coronary artery.

View larger version (168K): [in a new window]   Figure 7b.  Beam hardening effects caused by surgical clips. (a) Volume-rendered image from data acquired at 70% of the R-R interval shows a "blooming" artifact in which the surgical clips appear larger than their actual size. This beam hardening effect degrades depiction of the left internal mammary arterial graft (straight arrows), but not that of the right coronary artery (arrowhead) and left anterior descending artery (curved arrow). (b) Volume-rendered image from data acquired at 40% of the R-R interval is degraded by cardiac motion as well as by beam hardening effects (arrows). Arrowhead indicates the right coronary artery.

View larger version (152K): [in a new window]   Figure 8.  High-attenuating artifacts caused by pacing wires. Volume-rendered image shows multiple wires (straight arrows), which are distinguishable from the right coronary artery (arrowhead), left internal mammary artery, and left anterior descending artery (curved arrow) by differences in their attenuation and anatomic locations.

View larger version (129K): [in a new window]   Figure 9a.  High-attenuating artifact caused by a metallic stent. (a) Volume-rendered image depicts both the distal coronary artery segment and the stent (arrow) in the left anterior descending artery and, thus, indicates stent patency. (b) Multiplanar reformatted image shows a high-attenuating artifact (arrow) that prevents accurate evaluation of the stent lumen.

View larger version (147K): [in a new window]   Figure 9b.  High-attenuating artifact caused by a metallic stent. (a) Volume-rendered image depicts both the distal coronary artery segment and the stent (arrow) in the left anterior descending artery and, thus, indicates stent patency. (b) Multiplanar reformatted image shows a high-attenuating artifact (arrow) that prevents accurate evaluation of the stent lumen.

View larger version (143K): [in a new window]   Figure 10a.  High-attenuating artifacts caused by coronary arterial calcifications. (a) Volume-rendered image shows high-attenuating artifacts caused by calcifications, which prevent accurate evaluation of luminal patency in the left anterior descending artery (arrow) and the diagonal artery (arrowhead). (b) Multiplanar reformatted image shows variable contrast material filling in a patent but extensively calcified left anterior descending artery (arrow), as well as distal flow (arrowheads).

View larger version (114K): [in a new window]   Figure 10b.  High-attenuating artifacts caused by coronary arterial calcifications. (a) Volume-rendered image shows high-attenuating artifacts caused by calcifications, which prevent accurate evaluation of luminal patency in the left anterior descending artery (arrow) and the diagonal artery (arrowhead). (b) Multiplanar reformatted image shows variable contrast material filling in a patent but extensively calcified left anterior descending artery (arrow), as well as distal flow (arrowheads).

View larger version (89K): [in a new window]   Figure 11.  Low-attenuating artifact from an air bubble in contrast material. Axial source image shows an air bubble in the main pulmonary artery (arrow), which causes a low-attenuating artifact with beam hardening that obscures an adjacent coronary artery bypass graft.

View larger version (146K): [in a new window]   Figure 12a.  High-attenuating artifact caused by multiple overlapping contrast material-filled structures. Volume-rendered images from data acquired at 70% (a) and 40% (b) of the R-R interval show an artifact caused by the left atrial appendage (arrowheads), which overlies the saphenous venous graft to the obtuse marginal branch (arrow). The artifact is more severe in b than in a because the left atrial appendage is larger in early diastole, before the atrium has emptied, than in late diastole, after the rapid filling phase of the ventricle but before atrial contraction.

View larger version (148K): [in a new window]   Figure 12b.  High-attenuating artifact caused by multiple overlapping contrast material-filled structures. Volume-rendered images from data acquired at 70% (a) and 40% (b) of the R-R interval show an artifact caused by the left atrial appendage (arrowheads), which overlies the saphenous venous graft to the obtuse marginal branch (arrow). The artifact is more severe in b than in a because the left atrial appendage is larger in early diastole, before the atrium has emptied, than in late diastole, after the rapid filling phase of the ventricle but before atrial contraction.

View larger version (141K): [in a new window]   Figure 13a.  High-attenuating artifact caused by multiple overlapping contrast material-filled vascular structures. Volume-rendered image (a) and thin-slab maximum intensity projection image (b) show a cardiac vein (arrow) that overlies the left coronary arteries (arrowheads) and makes evaluation of stenosis more difficult. In such cases, an oblique thin-slab maximum intensity projection image may be helpful.

View larger version (124K): [in a new window]   Figure 13b.  High-attenuating artifact caused by multiple overlapping contrast material-filled vascular structures. Volume-rendered image (a) and thin-slab maximum intensity projection image (b) show a cardiac vein (arrow) that overlies the left coronary arteries (arrowheads) and makes evaluation of stenosis more difficult. In such cases, an oblique thin-slab maximum intensity projection image may be helpful.

View larger version (107K): [in a new window]   Figure 14a.  Improved depiction of a coronary artery bypass graft with delayed scanning. (a) Axial image obtained before peak contrast enhancement of the aorta and graft vessels shows an apparently patent saphenous venous graft (large arrow) and left internal mammary artery (arrowhead). Small arrows in a and b indicate metallic clips. (b) Axial image obtained with a 5-second delay after peak enhancement of the aorta shows an enhanced left internal mammary artery (arrowhead) and stenosis in the saphenous venous graft (large arrow).

View larger version (103K): [in a new window]   Figure 14b.  Improved depiction of a coronary artery bypass graft with delayed scanning. (a) Axial image obtained before peak contrast enhancement of the aorta and graft vessels shows an apparently patent saphenous venous graft (large arrow) and left internal mammary artery (arrowhead). Small arrows in a and b indicate metallic clips. (b) Axial image obtained with a 5-second delay after peak enhancement of the aorta shows an enhanced left internal mammary artery (arrowhead) and stenosis in the saphenous venous graft (large arrow).

View larger version (128K): [in a new window]   Figure 15a.  Image data postprocessing errors, apparent on a volume-rendered image compared with a multiplanar reformatted image. (a) Volume-rendered image shows deletion (straight arrow) of a left internal mammary artery bypass graft (curved arrow) to the left anterior descending artery, while a Y-graft of the left internal mammary artery to the obtuse marginal artery (arrowhead) is well depicted. (b) Multiplanar reformatted image shows patency in the left anterior descending artery (arrows).

View larger version (131K): [in a new window]   Figure 15b.  Image data postprocessing errors, apparent on a volume-rendered image compared with a multiplanar reformatted image. (a) Volume-rendered image shows deletion (straight arrow) of a left internal mammary artery bypass graft (curved arrow) to the left anterior descending artery, while a Y-graft of the left internal mammary artery to the obtuse marginal artery (arrowhead) is well depicted. (b) Multiplanar reformatted image shows patency in the left anterior descending artery (arrows).

View larger version (142K): [in a new window]   Figure 16a.  Motion blurring artifact, minimized with optimal selection of the reconstruction window. (a, b) Volume-rendered images from CT data acquired at 40% (a) and 70% (b) of the cardiac phase show two parallel saphenous venous grafts from the aorta to the diagonal artery (straight arrow) and from the aorta to the obtuse marginal artery (arrowhead). In a, the grafts appear to communicate, probably because of motion blurring near a metallic clip (curved arrow); in b, however, the separation of the grafts is clearly depicted. (c, d) Multiplanar reformatted images from data acquired at 40% (c) and 70% (d) of the cardiac phase show the same artifact (arrow), which is more severe in c than in d.

View larger version (143K): [in a new window]   Figure 16b.  Motion blurring artifact, minimized with optimal selection of the reconstruction window. (a, b) Volume-rendered images from CT data acquired at 40% (a) and 70% (b) of the cardiac phase show two parallel saphenous venous grafts from the aorta to the diagonal artery (straight arrow) and from the aorta to the obtuse marginal artery (arrowhead). In a, the grafts appear to communicate, probably because of motion blurring near a metallic clip (curved arrow); in b, however, the separation of the grafts is clearly depicted. (c, d) Multiplanar reformatted images from data acquired at 40% (c) and 70% (d) of the cardiac phase show the same artifact (arrow), which is more severe in c than in d.

View larger version (99K): [in a new window]   Figure 16c.  Motion blurring artifact, minimized with optimal selection of the reconstruction window. (a, b) Volume-rendered images from CT data acquired at 40% (a) and 70% (b) of the cardiac phase show two parallel saphenous venous grafts from the aorta to the diagonal artery (straight arrow) and from the aorta to the obtuse marginal artery (arrowhead). In a, the grafts appear to communicate, probably because of motion blurring near a metallic clip (curved arrow); in b, however, the separation of the grafts is clearly depicted. (c, d) Multiplanar reformatted images from data acquired at 40% (c) and 70% (d) of the cardiac phase show the same artifact (arrow), which is more severe in c than in d.

View larger version (107K): [in a new window]   Figure 16d.  Motion blurring artifact, minimized with optimal selection of the reconstruction window. (a, b) Volume-rendered images from CT data acquired at 40% (a) and 70% (b) of the cardiac phase show two parallel saphenous venous grafts from the aorta to the diagonal artery (straight arrow) and from the aorta to the obtuse marginal artery (arrowhead). In a, the grafts appear to communicate, probably because of motion blurring near a metallic clip (curved arrow); in b, however, the separation of the grafts is clearly depicted. (c, d) Multiplanar reformatted images from data acquired at 40% (c) and 70% (d) of the cardiac phase show the same artifact (arrow), which is more severe in c than in d.

View larger version (134K): [in a new window]   Figure 17a.  Competitive flow in a coronary artery bypass graft. (a) Volume-rendered image does not depict the left internal mammary artery graft to the left anterior descending artery (arrow), an omission that leads to a false impression of occlusion. (b, c) Conventional angiograms from the systolic (b) and diastolic (c) phases show the to-and-fro pattern of competitive flow (black arrow) between the left internal mammary artery (white arrow) and the left anterior descending artery (arrowhead), a dynamic that may have led to the false-positive CT angiographic finding of occlusion.

View larger version (130K): [in a new window]   Figure 17b.  Competitive flow in a coronary artery bypass graft. (a) Volume-rendered image does not depict the left internal mammary artery graft to the left anterior descending artery (arrow), an omission that leads to a false impression of occlusion. (b, c) Conventional angiograms from the systolic (b) and diastolic (c) phases show the to-and-fro pattern of competitive flow (black arrow) between the left internal mammary artery (white arrow) and the left anterior descending artery (arrowhead), a dynamic that may have led to the false-positive CT angiographic finding of occlusion.

View larger version (135K): [in a new window]   Figure 17c.  Competitive flow in a coronary artery bypass graft. (a) Volume-rendered image does not depict the left internal mammary artery graft to the left anterior descending artery (arrow), an omission that leads to a false impression of occlusion. (b, c) Conventional angiograms from the systolic (b) and diastolic (c) phases show the to-and-fro pattern of competitive flow (black arrow) between the left internal mammary artery (white arrow) and the left anterior descending artery (arrowhead), a dynamic that may have led to the false-positive CT angiographic finding of occlusion.

View larger version (161K): [in a new window]   Figure 18a.  Myocardial bridging in a coronary artery segment. (a) Volume-rendered image shows apparent narrowing in a middle segment of the left anterior descending artery (arrow). (b, c) Conventional angiograms show the typical milking effect: The lumen of the arterial segment (arrow) is compressed by myocardial contraction in the systolic phase (b) but recovers its normal diameter in the diastolic phase (c). (d) Multiplanar reformatted image provides excellent depiction of myocardial bridging (arrow).

View larger version (153K): [in a new window]   Figure 18b.  Myocardial bridging in a coronary artery segment. (a) Volume-rendered image shows apparent narrowing in a middle segment of the left anterior descending artery (arrow). (b, c) Conventional angiograms show the typical milking effect: The lumen of the arterial segment (arrow) is compressed by myocardial contraction in the systolic phase (b) but recovers its normal diameter in the diastolic phase (c). (d) Multiplanar reformatted image provides excellent depiction of myocardial bridging (arrow).

View larger version (155K): [in a new window]   Figure 18c.  Myocardial bridging in a coronary artery segment. (a) Volume-rendered image shows apparent narrowing in a middle segment of the left anterior descending artery (arrow). (b, c) Conventional angiograms show the typical milking effect: The lumen of the arterial segment (arrow) is compressed by myocardial contraction in the systolic phase (b) but recovers its normal diameter in the diastolic phase (c). (d) Multiplanar reformatted image provides excellent depiction of myocardial bridging (arrow).

View larger version (143K): [in a new window]   Figure 18d.  Myocardial bridging in a coronary artery segment. (a) Volume-rendered image shows apparent narrowing in a middle segment of the left anterior descending artery (arrow). (b, c) Conventional angiograms show the typical milking effect: The lumen of the arterial segment (arrow) is compressed by myocardial contraction in the systolic phase (b) but recovers its normal diameter in the diastolic phase (c). (d) Multiplanar reformatted image provides excellent depiction of myocardial bridging (arrow).