Triple-rule-out CT angiography using two axial scans with 16 cm wide-detector for radiation dose reduction.

OBJECTIVE

To explore the use of two consecutive axial scans in triple-rule-out (TRO) examination on a 16 cm wide-detector CT for radiation dose reduction.

MATERIALS AND METHODS

Sixty TRO patients were assigned to either study group (Group A, n = 30) or control group (Group B, n = 30). Group A used a two-phasic contrast injection: 25mgI/kg/s for 12 s in 1st and at 3.0 ml/s injection rate for 7 s in 2nd phase. The pulmonary artery, coronary artery and aorta were scanned in succession with two axial scans using smart-coverage technique. Group B used the conventional protocol of scanning pulmonary arteries first in helical, followed by coronary arteries in axial and aorta in helical mode with contrast injection of 25mgI/kg/s for 14 s. All images were reconstructed with 80% ASIR-V. The qualitative and quantitative image assessment and effective dose of the two groups were statistically compared.

RESULTS

The demographic data and quantitative measurements and qualitative image scores between the two groups were statistically the same (p > 0.05). However, Group A reduced radiation dose by 52% (2.67 ± 0.98 mSv vs. 5.65 ± 1.37 mSv) (p < 0.001).

CONCLUSION

Using two consecutive axial scans in triple-rule-out on a 16 cm wide-detector CT reduces radiation dose while maintaining image quality compared with the conventional TRO protocol.

KEY POINTS

• Triple-rule-out can be performed with two-axial scans on a wide-detector CT system. • TRO with two-axial scans maintain image quality compared with conventional protocol. • TRO with two-axial scans reduces 52% radiation dose over conventional protocol.