The effect of a whole-heart motion correction algorithm on image quality, calcium score, and risk category classification of non-contrast-enhanced cardiac CT.

Purpose: To evaluate the effect of a whole-heart motion correction algorithm (Snapshot freeze 2, SSF2) on image quality, calcium score, and risk category classification of non-contrast-enhanced cardiac CT.

Materials and methods: Sixty-one coronary calcium scoring scans performed on a 256-row detector CT were included. Images of standard reconstruction without motion-corrected (STD) and with SSF2 were compared. The image quality was graded by consensus of two experienced radiologists using a four-point Likert scale. The diameter of the major and minor axes at the heaviest point of a dominant calcification, as well as its volume, were measured. The Agatston score, volume score, and corresponding risk category for each patient were recorded. Paired t test, Wilcoxon test, and Bland-Altman plot were used for statistical analysis.

Results: Image quality was significantly improved with SSF2 (P < 0.001). The mean diameters of the major and minor axes were 10.5 ± 5.3 mm and 6.4 ± 6.8 mm for STD images, and 7.2 ± 4.6 mm and 4.2 ± 5.5 mm for SSF2 images, resulting in a mean volume of 149.6 ± 206.1mm³ and 118.7 ± 184.6mm³, respectively (all P < 0.001). The mean Agatston score and volume score for STD images were 493.9 ± 585.9 and 415.7 ± 478.4, respectively, and decreased to 409.8 ± 505.4 and 337.7 ± 399.7, respectively, after motion correction (P < 0.001). The risk category changed significantly as 8 (13.1%) and 10 (16.4%) patients, were downgraded after motion correction based on either Agatston score (P = 0.008) or volume score (P = 0.002), respectively.

Conclusion: Motion correction with SSF2 in non-contrast-enhanced cardiac CT improves the image quality at both the patient and lesion level, resulting in a significant reduction in calcium score and risk category downgrade.