Imaging of the coronary arteries by means of multislice helical CT: Optimization of image quality with multisegmental reconstruction and variable gantry rotation time

Purpose: To evaluate the potential of multisegmental reconstruction and variable gantry rotation time for reducing motion-induced artifacts in coronary artery imaging by multislice helical CT. Materials and Methods: The data sets of 20 patients (8 with HR < 60 bpm, 12 with HR > 60 bpm) were analyzed. The patients underwent multislice helical CT (Aquilion 8, Toshiba, Otawara, Japan) using the following parameters: 0.5 mm slice thickness, 250 mA, 120 W, pitch of 0.25 and variable gantry rotation times of 400, 500, or 600 msec. Images were generated by halfscan and multisegmental reconstruction. In 9 coronary segments of each patient, the presence and severity of motion artifacts were assessed and graded on a scale between 5 (no artifacts) and 1 (heaviest artifacts). Results: Diagnostically relevant motion artifacts were rare at low heart rates (< 60 bpm) for both types of image reconstruction (4% of all segments). Higher heart rates (> 60 bpm) were associated with an increase in motion artifacts on halfscan reconstructions (33% of all segments, p < 0.05) but not on multisegmental reconstructions (4% of all segments). At low heart rates mean image quality did not differ between multisegmental and halfscan reconstruction (4.28 +/- 0.37 vs. 4.22 +/- 0.41; p > 0.05), whereas at higher heart rates image quality was better for multisegmental reconstruction than for halfscan reconstruction (4.23 +/- 0.47 vs. 3.11 +/- 0.63; p < 0.05). Conclusion: Multisegmental reconstruction with variable gantry rotation times suppresses motion artifacts and thus improves assessment of the coronary arteries in patients with higher heart rates.