Purpose The purpose of this work was to evaluate coronary artery motion characteristics and determine optimal electron beam tomography (EBT) scan time during the cardiac cycle to image the coronary arteries. Method This study evaluated the movement of coronary arteries in 20 EBT cine studies, at rest and during stress, obtained for evaluating coronary artery disease. The proximal, middle, and distal segments of each coronary artery were measured at multiple times during the cardiac cycle. The motion distance (mm) and velocity (mm/s) of each segment of the coronary arteries were then measured to establish the motion that occurs in the x and y axes during different times in the cardiac cycle. Results Coronary artery velocity ranged from 22.4 to 108.6 mm/s. The least motion (and slowest speed) occurred between 30-50 and 40-60% of the R-R interval at rest and stress, respectively. The right coronary artery moved the greatest in the x and y planes (highest speed and spatial change), followed in decreasing order by the circumflex, left main, and left anterior descending arteries. The phase of the cardiac cycle with the greatest coronary artery motion was between 0 and 20% of the R-R interval. Conclusion Coronary artery motion varies greatly throughout the cardiac cycle. To minimize cardiac motion during tomographic imaging of the coronary arteries, we recommend 40-50% R-R interval as an electrocardiographic trigger time and avoiding the use of image acquisition times of >100 ms.

Coronary artery motion in electron beam tomography.

Purpose Motion artifacts of the ascending aorta may impair image quality and simulate an intimal flap or a false channel. The purpose of this study is to evaluate the prevalence, amplitude, and extent of motion artifacts of the aorta in spiral CT and to specify the effects of acquisition and reconstruction parameters on these artifacts. Method One hundred seventy-one thoracic spiral CT examinations were retrospectively analyzed by two reviewers. The analysis sought to determine the presence, location, amplitude, and extent of artifacts of the ascending aorta. Results Aortic artifacts were detected on spiral CT in 57% of cases. The mean amplitude and mean extent were 4+/-4 and 6+/-7 mm, respectively. Artifacts in the ascending aorta were significantly higher with the 360 degrees linear interpolation (LI) algorithm than with the 180 degrees LI algorithm. Conclusion The prevalence of motion artifacts on spiral CT is higher in this study than the reported prevalence in incremental CT. However, this higher prevalence is significantly reduced when the 180 degrees LI algorithm is used.

Motion artifacts of the aorta simulating aortic dissection on spiral CT.

OBJECTIVE. Our aim was to evaluate the effects of heart rate on aortic motion artifacts on 0.5-sec non-ECG-assisted thoracic MDCT.MATERIALS AND METHODS. A total of 124 non-ECG-assisted thoracic MDCT scans with satisfactory simultaneous ECG data were reviewed. Scans were grouped according to patient heart rates (beats per minute [bpm]: group A, 46-55; B, 56-65; C, 66-75; D, 76-85; E, 86-95; and F > 95). The groups were compared regarding the presence, locations, and spatial distributions of pulsation artifact, number of slices affected, maximum amplitude of pulsation, continuity of artifact, and the presence of superior vena cava (SVC) pseudoflaps.RESULTS. Of the 124 scans, 114 (91.9%) had aortic motion artifacts, with prevalence ranging from 85.3% (66-75 bpm) to 100% (65 bpm or less). Of the 114 motion artifacts, all affected the ascending aorta, 105 (92.1%) involved the left anterior and right posterior aspects of the aortic circumference, and 106 (93%) were associated with SVC pseudoflaps. Group B had s...

https://www.ajronline.org/doi/pdfplus/10.2214/ajr.184.4.01841225

Effects of heart rate on motion artifacts of the aorta on non-ECG-assisted 0.5-sec thoracic MDCT.

Angiography is the gold standard for the imaging of vessels, while computed tomography (CT) is useful for imaging of bone and soft tissue. The term “computed tomographic angiography” (CTA) encompasses all methods that use CT to image vascular structures with the help of contrast agents. This chapter concentrates on CTA performed with intravenous injections. A stack of cross-sectional images is generated, providing information on the vascular structures and their relation to the surrounding anatomy. Since there is no superimposition of vessels, the real 3D geometry can be derived from the data set, which is particularly important for visualization of convoluted and curved vascular trajectories. After injection of a contrast bolus, data acquisition must be complete within a limited time frame, as the concentration of the contrast agents in the blood pool decreases over time. This time frame is influenced by injection techniques and individual patient physiology.

P Stark

Papers

Motion artifact simulating aortic dissection on CT.