The scanning protocol of 256-slice spiral CT for bronchial artery CT angiography

Objective:Comparison of different scanning and injection protocols for bronchial artery CT angiography(CTA).Methods:Eighty cases scheduled for bronchial artery CTA were randomly assigned into four groups according to the injection protocol.Cases in group 1 to group 3 adopted the injection rate of 4,5 and 6 ml/s respectively,and used automatic threshold preset at 300 HU to trigger the initiation of the scan,with total contrast dose of 1.5 ml/kg body weight.Cases in the group 4 adopted an injection rate of 6 ml/s,triggering threshold of 120 HU,and 1.0 ml/kg body weight of contrast.High density contrast(350 mgI/ml)was used in all cases.The CT values of pulmonary artery,superior vena cava,aortic artery and bronchial artery before and after enhanced scanning were measured in the 4 groups.Numbers of cases with excellent image quality of bronchial artery display were also evaluated.Results:The CT values of pulmonary artery and superior vena cava among four groups hadn't significant difference(P 0.05).The CT values of aortic artery in group 4 were higher than other three groups significantly(P 0.05).The CT values of bronchial artery in group 4 were higher than group 1 and group 2 significantly(P 0.05).The excellent rate of bronchial artery CTA for group one to group four were: 50%,55%,65% and 80%,respectively.Conclusion:This research showed that the injection rate of 6 ml/s,triggering threshold of 120 HU,1.0 ml/kg body weight of high density contrast dose provide higher contrast,and it's on optimal protocol for bronchial artery CTA.