Purpose: We aimed to assess the heart rate (HR) dependent presence and degree of motion artifacts in coronary CT angiography (CCTA) scans acquired by CG compared to a conventional 256-slice CT scanner.
Methods: In this retrospective study, we have compared the images of 75 patients who underwent CCTA with CG (240 ms rotation time) to 75 scans acquired by a 256-slice CT scanner (270 ms rotation time). The two groups were matched for age and gender. The mean age of the groups was 57.3 years, 49.3 % males. Motion artifacts were assessed using a Likert-type scale, ranging from 1 to 4 (1: non-diagnostic, 2: severe motion artifacts, 3: mild motion artifacts, 4: no motion artifacts). The patients were divided into 3 equal groups (50-50-50 patients) according to HR ranges during image acquisition (51-60/min, 61-70/min, above 71/min). The image quality of each of the 3 groups in both scanners was compared using Wilcoxon rank-sum test.
Results: The CG scanner had a better image quality, with reduced motion artifacts as compared to the 256-slice scanner (mean Likert-score 2.7 ± 0.9 vs. 2.3 ± 0.7, respectively, p<0.003). The CG images had higher Likert-scores in all 3 heart rate ranges (51-60/min, 61-70/min, 71+/min), which was statistically significant in the lower 2 of the 3 ranges (p=0.025, p=0.043, p=0.156, respectively).
Conclusion: The new 560-slice CG scanner with 240 ms gantry rotation time allows for CCTA image acquisition with reduced motion artifacts as compared to a 256-slice scanner. The beneficial effect of fast gantry rotation was especially present at HR below 70/min.