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Updated: Jul 24, 2026
Cardiac Magnetic Resonance Imaging at 7 Tesla
Published on: January 6, 2019
Coronary artery motion during the cardiac cycle and optimal ECG triggering for coronary artery imaging
1Department of Medicine, Division of Cardiology, Harbor-UCLA Medical Center and Saint John's Cardiovascular Research Center, Torrance, California, USA.
Insights
Optimizing electrocardiographic (ECG) trigger timing for coronary artery imaging reduces motion artifacts. The ideal ECG trigger depends on patient heart rate, improving coronary artery screening accuracy.
Area of Science:
- Cardiovascular imaging
- Medical physics
Background:
- Coronary artery motion can cause artifacts in imaging studies.
- Minimizing motion is crucial for accurate diagnosis and screening.
Purpose of the Study:
- To investigate coronary artery motion characteristics.
- To determine optimal electrocardiographic (ECG) trigger timing to minimize motion artifacts.
Main Methods:
- Electron beam tomography (EBT) was used to acquire cardiac cycle data in 70 subjects.
- Motion distance and velocity of coronary arteries were measured.
- ECG triggering was employed to capture images at 58-ms intervals.
Main Results:
- Coronary artery motion varied with the cardiac cycle and increased with heart rate.
- Optimal ECG trigger times were identified based on heart rate (e.g., 35-70% of R-R interval for <70 bpm).
- Left circumflex and right coronary arteries showed similar motion; LAD artery motion was consistent.
Conclusions:
- Optimal ECG trigger timing is heart rate-dependent for coronary artery screening.
- Tailoring trigger times reduces motion and artifacts, enhancing 100-ms acquisitions.
Rationale And Objectives:
Our purpose was to investigate the motion characteristics of the coronary arteries and determine optimal electrocardiographic (ECG) trigger time during the cardiac cycle to minimize motion artifacts.
Methods:
Contrast-enhanced multislice movie studies of electron beam tomography (EBT) images were performed on 70 subjects. The EBT datasets, which covered an entire cardiac cycle at 58-ms intervals, were acquired for a short-axis view of the heart with ECG triggering. The pixel values along x and y axes were measured at multiple intervals during the cardiac cycle to establish the motion distance and velocity of three major coronary arteries.
Results:
Coronary artery motion varied greatly throughout the cardiac cycle in three major coronary arteries and increased with the patient's baseline heart rate. The greatest and lowest velocities of coronary arterial movement during the cardiac cycle were determined. Based on the lowest velocity of right coronary artery movement during the cardiac cycle, the optimal ECG trigger times were located at approximately 35% (31.4%-37.6%) or 70% (68.7%-71.4%) of the R-R interval in patients whose resting heart rate was < or =70 beats per minute (bpm); at 50% (47.2%-61.1%) of the R-R interval in the 71- to 100-bpm group; and at 55% (52.8%-59.1%) of the R-R interval in the >100-bpm group. Our data demonstrated that the motion characteristics of the left circumflex artery were quite similar to those of the right coronary artery and that the left anterior descending coronary artery had no significant differences in motion throughout the cardiac cycle. A minimum scan speed of 35.4 to 75.5 ms per slice is needed to completely diminish cardiac motion artifacts (in-plane coronary artery motion with <1-mm displacement).
Conclusions:
For coronary artery screening, the optimal ECG trigger time should be determined according to the patient's heart rate, thus greatly reducing motion and motion artifacts during 100-ms acquisitions.
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