What are coronary artery motion artifacts on coronary computed tomography angiography (CCTA)?

Updated: Dec 21, 2017
  • Author: Eugene C Lin, MD; Chief Editor: Eugene C Lin, MD  more...
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Answer

Answer

Artifacts from motion of the coronary arteries result in image blurring. The right coronary artery is often most affected by motion artifact.

Coronary artery motion: Axial CT images reconstruc Coronary artery motion: Axial CT images reconstructed at 90% (A) and 70% (B) of the R-R interval demonstrate the importance of imaging during the phase of least cardiac motion.

General strategies to decrease motion artifact are to increase the time during the cardiac cycle where there is the least motion and to image as quickly as possible (increase temporal resolution).

Motion can be minimized by reconstructing the data during a phase where there is minimal motion. Choosing the optimal phase of the R-R cycle to reconstruct the data is discussed in the image reconstruction section, below. Decreasing the heart rate with beta blockers has the advantages of decreasing the motion velocity of the coronary arteries [4] and increasing the relative and absolute duration of the diastolic rest period in the cardiac cycle.

Temporal resolution can be increased in 2 ways. Dual-source CT scanners have substantially higher temporal resolution. With a single-source scanner, one way to increase temporal resolution, typically used in patients with higher heart rates, is to use a multiple-segment reconstruction technique. In this technique, the data required for image reconstruction are selected from multiple sequential heart cycles. This technique requires retrospective gating and a regular heart rate. [4] For data from several cardiac cycles to be used for image reconstruction, the same position has to be covered by the detector during consecutive cardiac cycles. Thus, the pitch must be lowered, which will increase radiation dose. Multi-segment reconstruction is only effective in improving temporal resolution at specific heart rates (the heart rate and gantry rotation time need to be desynchronized).


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