How is the reconstruction window determined in 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

The coronary arteries are optimally imaged when there is the least cardiac motion. This occurs during so-called rest periods, which is typically in middiastole (diastasis). Coronary motion is also minimal during end-systole (isovolumic relaxation), but this is of shorter duration than diastolic diastasis at low heart rates.

With dual-source computed tomography (CT) scanning at low heart rates, the optimal reconstruction window is often 70–75% of the R-R interval (diastolic) for all of the coronary arteries. A 30-35% systolic window may occasionally be helpful for the right coronary artery. [65] As heart rate increases, diastole shortens relative to systole, and diastasis shortens dramatically. The optimal reconstruction window transitions from diastole to systole around 75-85 bpm. [4, 66] At high heart rates, the optimal reconstruction windows are 85-90% (diastole) and 40-45% (systole). [66] End-systolic reconstruction windows [63] may be helpful in patients with atrial fibrillation, as the systolic rest period will be less variable than the diastolic rest period.

Use of a fixed reconstruction window, [63] such as 50 msec rather than a percentage of the R-R interval, is helpful in patients with atrial fibrillation and variable R-R intervals.


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