RESUMEN
Objective To investigate the value of automatic spectral imaging mode selection and adaptive statistical iterative reconstruction(ASIR) in upper abdominal enhanced CT with low contrast agent dose, and to optimize the combination of monochromatic energy level and ASIR percentage.Methods 100 patients underwent upper abdominal enhancement CT were randomly assigned into control group (n=50) and study group (n=50).In the control group, tube voltage of 120 kVp and contrast medium of 450 mg I/kg were used with the images reconstructed using 40% ASIR.In the study group, CT spectral imaging with automatic spectral imaging mode selection and contrast medium of 300 mg I/kg were used,and monochromatic images (40-65 keV,intervals of 5 keV) were reconstructed using 40%-60% ASIR (intervals of 10%), respectively.CT value, image noise and contrast-to-noise ratio of the liver, pancreas, aorta and portal vein and radiation dose were compared using two independent samples t test.Overall image quality was assessed by Mann-Whitney U test.Results All image quality indexes in 60 keV with 40% ASIR, 55-60 keV with 50% ASIR in the study group were equal to or better than the control group.There was no significant difference in radiation dose between control group and study group.Conclusion Combined automatic spectral imaging mode selection with ASIR, upper abdominal enhanced CT with low contrast agent dose could improve image quality compared to 120 kVp with 40% ASIR, without increasing radiation dose.