RESUMEN
Objective:To investigate the feasibility of reducing radiation dose in coronary CT angiography for patients with arrhythmia with absolute phase and narrow window in prospective electrocardiogram-gating.Methods:200 patients with arrhythmia underwent coronary CT angiography procedure with prospective electrocardiogram-gating adaptive sequence in dual source CT were randomly divided into 2 groups according to the scan mode. Group A was scanned with absolute phase and narrow window(250-450 ms) and group B uesd relative phase and wide window (30%-75%). The other parameters and injection protocol of contrast media were the same in 2 groups. Both image quality and radiation dose of the 2 groups were analyzed.Results:No significant difference of image quality was found between the 2 groups. CTDI vol, DLP, E of group A were all lower than those in group B [CTDI vol : (16.71±8.35) vs.(29.35±17.90)mGy , DLP: (231.04±114.86) vs.(398.27±238.40)mGy·cm , E: (3.23±1.60) vs.(5.57±3.33)mSv, t=-6.40, -6.32、-6.32, P<0.05] . The patients with repeat scan cycles in group A and group B were 81 vs. 22 for 0 cycle , 17 vs. 62 for 1 cycle, 2 vs. 10 for 2 cycles, 0 vs. 6 for 3 cycles( χ2=70.76, P<0.05). Conclusions:The prospective electrocardiogram-gating adaptive CCTA sequence with absolute phase and narrow window can reduce radiation dose while the image quality meets the requirementsfor patients with arrhythmia.