The Feasibility Of Application Of Gemstone Optimal Monochromatic Images With Patient-based Low Contrast Medium Protocol For Lower Extremity Angiography

Objective To investigate the feasibility of lower extremity artery CT angiography in gemstone spectral image(GSI)associated with patient-based lower contrast medium dose.Methods Altogether 75 patients were prospectively and randomly divided into conventional CT routine dose group,GSI routine dose group and GSI low dose group.Conventional routine group and GSI routine group were scanned by using 120 kVp and GSI mode,respectively,with the same contrast medium(CM)dose of 2mL/kg and injection rate of 3.5mL/s,the other scanning parameters were the same.And images using 120 kVp(with FBP)and optimal kilo electron volt(keV)(with 50%ASIR)were reconstructed.The CM dose and injection rate of GSI low dose group(with 50%ASiR)were 1.6mL/kg and 2.8mL/s.The obtained images of three groups were compared in terms of arterial attenuation,contrast-to-noise ratio(CNR),background noise(BN)and subjective image quality scores.The value of average intake of iodine,dose length produce(DLP)and effective dose(ED)was recorded.Results were statistically analyzed by one-way analysis of variance and Bonferroni correction.The subjective scores among the three groups were analyzed by using Kruskal-Wallis H test.Results According to exclusion criteria,60 patients were enrolled finally and 20 cases in each group.All quantitative parameters from three groups demonstrated that GSI routine group showed the highest CT value and CNR and showed the lowest BN and ED in all arteries(P<0.01),whereas there was no statistical difference in BN and ED(P>0.05)between two GSI groups.GSI low dose group manifested higher CT value and CNR(P<0.05),except anterior tibial artery(P=0.162;P=0.376),compared with conventional group.And GSI low dose group demonstrated the lowest intake rate of iodine and injection velocity.The scores of three groups image quality assessed by physician 1 and 2 were 82:95:90 and 80:96:89,respectively,with statistical difference(H=4 954,P<0.01;H=17.726,P<0.01).And the image quality of GSI low dose group was superior to conventional group.Conclusion Gemstone spectral optimal monochromatic images for lower extremity CTA could provide better CNR and image quality while significantly reduce the radiation dose,and simultaneously reduce the individualized intake of iodine contrast agent.