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Purpose The aim of the study was to investigate the image quality and radiation exposure of contrast enhanced CT enterography with low tube voltage and a low concentration of contrast agent combined with adaptive statistical iterative reconstruction(ASIR).Materials and methods From October 2015 to February 2016,137 patients(65 female,72 male,mean age 54±14 years)underwent contrast enhanced CT enterography using a 64-slice multi-detector computed tomography(MDCT)scanner(Discovery CT750 HD,GE Healthcare,USA).All cases were randomly assigned to two groups.Group A(n=79)was examined by CT with low tube voltage according to their BMIs(BMI<23 kg/m2,80 kVp; BMI≥23 kg/m2,100 kVp)and a low concentration of contrast agent(270 mgI/mL).The raw data were reconstructed with standard filtered back projection(FBP)and 50%ASIR.Group B(n=58)underwent conventional CT at 120 kVp and 350 mgI/mL contrast agent with FBP.The CT dose index volume(CTDIvol)and dose length product(DLP)were recorded,and the effective dose(ED)and total contrast medium dosage were calculated and compared.The CT values,signal-to-noise ratio(SNR),and contrast-to-noise ratio(CNR)of the bowel wall,gastrointestinal lesions,and mesenteric vessels were assessed and compared statistically.The subjective image quality was assessed by two radiologists using a five-point Likert scale(1=poor; 2=acceptable; 3=moderate; 4=good; 5=excellent).Result Compared with Group B,the CTDIvol,ED,DLP and total iodine contrast medium dosage in Group A were decreased by 25.2%,25.7%,25.7%,and 26.07%,respectively.The average qualitative image quality scores of the FBP image of Group A(4.02±0.39)and 50%ASIR image of Group A(4.02±0.37)were lower than the FBP image of Group B(4.21±0.55),but the difference was not statistically significant(P>0.05).The mean value of the noise(SD)in the 50%ASIR image of Group A was significantly lower than the FBP image of Group A(13.18+2.687 vs.15.69±3.60,P<0.001).The CT value,CNR and SNR were significantly higher in the SMA,SMV,and gastrointestinal lesions in the 50%ASIR image of Group A(P<0.05).Conclusions Compared with the conventional protocol,CT enterography examinations performed at low tube voltage,a low concentration of contrast agent,and the 50%ASIR algorithms produce a diagnostically acceptable image quality with a mean ED of 6.34 mSv and a total iodine dose reduction of 26%.