CT Pulmonary Angiography With Low Tube Voltage And Low Contrast Dose Reducing Beam-hardening Artifact: The Feasibility With Third-generation Dual-source CT

Objective: To explore the feasibility of CT pulmonary angiography(CTPA)with low tube voltage and low contrast medium dose on the third-generation dual-source(DS)CT and its value in reducing the beam-hardening artifacts.Materials and Methods: From October 2016 to February 2017,60 patients underwent with CTPA examination in Tianjin Medical University General Hospital were analyzed prospectively.The patient's main complaints were chest tightness,suffocation,coronary heart disease and so on.All patients were randomly divided into 2 groups: standard group(90kV,30 ml CM)and �double-low� group(70kV,20 ml CM).The observed pulmonary artery branches include pulmonary trunk,right pulmonary artery,left pulmonary artery,right upper lobe pulmonary artery,right interlobar pulmonary artery,right middle lobe pulmonary artery,left upper lobe pulmonary artery,right lower lobe pulmonary artery and left lower lobe pulmonary artery.Objective image quality was evaluated with CT attenuation,signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR),and beam-hardening artifact index(AI).Subjective image quality was assessed with five-point scale.Radiation dose was also recorded.The parameters of objective and subjective image quality were compared with Wilcoxon rank sum test and independent-sample test.AI of different branches of pulmonary artery in each group was compared by one-way ANOVA test.Results: There was no significant difference(CT attenuation,SNR,and CNR)between the two groups in objective image quality(P>0.05).In �double-low� group,radiation dose was significantly lower than that of standard group(P<0.05).The AIs of right pulmonary artery(RPA)and right upper lobe pulmonary artery(RULPA)in standard group were significantly higher than those in "double-low group"(t=5.38,P<0.01;t=7.82,P<0.01).The AIs of RPA and RULPA were higher than those in other branches in standard group,while no difference was found in �double-low�group.The subjective image quality of �double-low� group was also better than that of standard group(Z=4.33,P<0.01;Z=4.53,P<0.01).Conclusion: CTPA with low tube voltage and low contrast medium dose by third-generation CT can obtain satisfactory image quality and reduce the influence of beam-hardening artifacts in the RPA and RULPA.