During which phase of the cardiac cycle is ECG Gating CT triggered to capture images?

The correct answer is the diastolic phase of the cardiac cycle. During this period, the heart muscle is relaxed, allowing the chambers of the heart to fill with blood. This relaxation phase is beneficial for obtaining clear and stable images during CT scans because the motion of the heart is minimized, reducing the likelihood of artifacts caused by heartbeats.

Diastole provides the best timing for imaging because the heart's walls are not contracting, therefore, capturing images during this phase leads to clearer representation of cardiac structures and allows for accurate assessment of conditions such as left atrial appendage size, shape, and any potential thrombus formation.

In contrast, capturing images during systole would coincide with the contraction of the heart, resulting in additional movement and less clarity in the images, making it harder to evaluate the fine details needed for effective diagnosis and intervention planning related to left atrial appendage occlusion. Early diastole and late systole carry their own limitations; in early diastole, the heart just becomes more relaxed but may still exhibit some residual motion, while late systole occurs near the end of contraction, which could also introduce variability in timing and decrease image quality.