Comparison of prospectively ECG-triggered high-pitch spiral and sequential acquisition for coronary CT angiography using the second generation of dual-source CT

Objective:Prospective high pitch acquisition in cardiac imaging allows to obtain the images with lose dose,which however has not been studied comprehensively.The aim of this study was to compare prospective high-pitch spiral(FLASH) and the sequential acquisitions in coronary CT angiography using the 2nd generation of dual-source CT.Methods;One hundred subjects with suspected coronary artery disease with heart rate ≤70 bpm and heart rate fluctuation less than 10 bpm underwent coronary CTA on the 2nd generation of dual-source CT.Subjects were divided into two groups with different acquisitions randomly. Prospective ECG-triggering coronary CT angiography protocol;Using a z-f lying focal spot;the simultaneous acquisition of data in 0.6 mm;reconstruction slice thickness 0.75 mm;rotation time 0.28 s;Using single-cycle reconstruction,a temporal resolution of 75 ms;tube settings were 100 kV(BMI24 kg/m~2)and 120 kV(BMI≥24 kg/m~2).The additional parameters for FLASH was data acquisition obtained at 60% of the R-R interval,whereas 35% ～75% of the R-R interval for sequential scan.Image quality(IQ)was evaluated using a four-point scale(1=excellent,4=unevaluable)by two experienced radiologists by consensus.The rank sum test was used to compare the image quality between two groups.T-test was used to compare the radiation dose between two groups.Results:All subjects performed scans successfully.FLASH yielded good IQ in 98.21%, and sequential in 98.56%.There was no significant difference in mean IQ score between groups(1.30± 0.60 vs.1.28 ±0.56, P=0.625).While there was significant difference in the mean effective radiation dose(0.99 ±0.34 vs.4.80 + 2.21 mSv,P= 0.000).Conclusion:Compared with the sequential acquisition,the prospective high-pitch spiral scan can remarkably reduce radiation dose while preserving good image quality in patients with a low and stable heart rate(≤70 bpm).