Relationship between heart rate and optimal reconstruction phase in dual-source CT coronary angiography

To evaluate reconstruction image quality at the systolic and diastolic cardiac phases and determine the optimal phase for reconstruction according to heart rate when using dual-source computed tomography (CT) with 75 ms temporal resolution.

We retrospectively reviewed the CT datasets of 35 patients with regular heartbeats who underwent coronary CT angiography. Images were reconstructed in 2% steps between 32 and 78% of the beat-to-beat interval. Two experienced radiologists determined the reconstruction interval with the fewest motion artifacts and the motion score of each vessel for the systolic and diastolic phases. Subgroup analysis was performed in patients having heart rates of <70, 70-80, and >80 beats per minute (bpm).

In the subgroup with heart rates of <70 bpm, the diastolic phase reconstruction image quality was significantly better than for the systolic phase (P < .01). In the 70-80 bpm and >80 bpm subgroups, no significant difference was observed. In the diastolic phase, the image quality of the <70 bpm subgroup was significantly better than for the >80 bpm subgroup (P < .05). In all systolic phase subgroups and other diastolic phase subgroups, no significant difference was observed.

Using a DSCT scanner with 75 ms temporal resolution, reconstruction at the diastolic phases should be used for patients with heart rates <70 bpm. For heart rates >70 bpm, larger studies are necessary to determine whether reconstruction at the systolic, diastolic, or both phases should be used.