ECG-gated reconstructed multi-detector row CT coronary angiography: effect of varying trigger delay on image quality

Radiology. 2001 Sep;220(3):712-7. doi: 10.1148/radiol.2203010055.


Purpose: To evaluate the effectiveness of electrocardiographically (ECG)-gated retrospective image reconstruction for multi-detector row computed tomographic (CT) coronary angiography in reducing cardiac motion artifacts and to evaluate the influence of heart rate on cardiac image quality.

Materials and methods: Sixty-five patients with different heart rates underwent coronary CT angiography. Raw helical CT data and ECG tracings were combined to retrospectively reconstruct at the defined consecutive z position with a temporal resolution of 250 msec per section. The starting points of the reconstruction were chosen between 30% and 80% of the R-R intervals. The relationships between heart rate, trigger delay, and image quality were analyzed.

Results: Optimal image quality was achieved with a 50% trigger delay for the right coronary artery and 60% for the left circumflex coronary artery. Optimal image quality for the left anterior descending coronary artery was equally obtained at 50% and 60% triggering. A significant negative correlation was observed between heart rate and image quality (P <.05). The best image quality was achieved when the heart rate was less than 74.5 beats per minute.

Conclusion: To achieve high image quality, the heart rate should be sufficiently slow. Selection of appropriate trigger delays and a decreasing heart rate are effective to reduce cardiac motion artifacts.

MeSH terms

  • Adult
  • Aged
  • Coronary Angiography*
  • Electrocardiography*
  • Female
  • Heart Rate / physiology*
  • Humans
  • Male
  • Middle Aged
  • Tomography, X-Ray Computed*