Effect of a novel motion correction algorithm (SSF) on the image quality of coronary CTA with intermediate heart rates: segment-based and vessel-based analyses.

PURPOSE

To evaluate the effect of SnapShot Freeze (SSF) reconstruction at an intermediate heart-rate (HR) range (65-75bpm) and compare this method with single-sector reconstruction and bi-sector reconstruction on segmental and vessel bases in retrospective coronary computed tomography angiography (CCTA).

MATERIALS AND METHODS

Retrospective electrocardiogram-gated CCTA was performed on 37 consecutive patients with HR between 65 and 75bpm using a 64-row CT scanner. Retrospective single-sector reconstruction, bi-sector reconstruction, and SSF were performed for each patient. Multi-phase single-sector reconstruction was performed to select the optimal phase. SSF and bi-sector images were also reconstructed at the optimal phase. The images were interpreted in an intent-to-diagnose fashion by two experienced readers using a 5-point scale, with 3 points as diagnostically acceptable. Image quality among the three reconstruction groups were compared on per-patient, per-vessel, and per-segment bases.

RESULTS

The average HR of the enrolled patients was 69.4±2.7bpm. A total of 111 vessels and 481 coronary segments were assessed. SSF provided significantly higher interpretability of the coronary segments than bi-sector reconstructions. The qualified and excellent rates of SSF (97.9% and 82.3%) were significantly higher than those of single-sector (92.9% and 66.3%) and bi-sector (90.9% and 64.7%) reconstructions. The image quality score (IQS) using SSF was also significantly higher than those of single-sector and bi-sector reconstructions both on per-patient and per-vessel bases. On per-segment analysis, IQS was improved in most segments (9/14).

CONCLUSION

The SSF algorithm can provide acceptable diagnostic image quality in coronary CTA for patients with intermediate HR.