| Objective To explore the application of low-concentration iodine contrast agent(270mg I / ml)and low tube voltage(100k Vp)in enhanced CT examination of chest and upper abdomen.In order to reduce the radiation dose and the use of iodine contrast agent,it provides the basis for formulating the optimal contrast agent injection scheme,scanning technology and conditions,iterative reconstruction technology for the human body type of the country.Materials and research methods 1.Chest This study included clinical data of 216 patients undergoing chest enhancement CT examination in 12 different hospitals according to the inclusion criteria.The patients were randomly divided into 4 groups:group A: tube voltage 120 k Vp,contrast agent iohexol 350 mg I / ml,included 53 cases;group B: tube voltage 100 k Vp,contrast agent iohexol 350 mg I / ml,included 42 cases;group C: Tube voltage 120 k Vp,contrast agent iodixanol 270 mg I / ml,included 61cases;Group D: tube voltage 100 k Vp,contrast agent iodixanol 270 mg I / ml,included60 cases.The subjective evaluation of the image quality of the chest CT enhancement examination of the 4 groups of patients was independently blinded evaluated by two radiologists with more than 10 years of experience.The consistency of the scores of the two doctors was analyzed by weighted kappa test for statistical comparison.Measure the CT value and noise of the pulmonary artery of the enhanced image,and calculate the image contrast noise ratio(CNR)as the objective evaluation index of image quality.Record the volume CT dose index(CTDIvol)and dose length product(DLP)automatically obtained by the device after CT scanning of each patient,and calculate the effective dose(ED): ED = 0.0143 × DLP.The imaging diagnosis results of the four groups of CT-enhanced images obtained under different conditions were compared with the pathological findings of the gold standard pathology to evaluate the accuracy of CT imaging diagnosis.2.Upper Abdomen In this study,120 patients with BMI underwent CT scan of upper abdomen in the normal range were randomly divided into group A conventional tube voltage iodine contrast agent(120k Vp,300 mg I / ml),group B conventional tube voltage low concentration iodine contrast Agent(120k Vp,270 mg I / ml),group C low tube voltage conventional concentration iodine contrast agent(100k Vp,300 mg I / ml)and group D low tube voltage low concentration iodine contrast agent(100k Vp,270 mg I / ml),30 patients in each group.The four groups of images were reconstructed using a combination of40% ASIR algorithm and FBP algorithm;the CT values,image noise,contrast noise ratio(CNR)of the same parts of the four groups of portal phase images were measured and compared;the volumetric CT dose index(CTDIvol)was recorded;Subjective image quality evaluation was performed on the obtained images according to the 4-point method,and the consistency of the score results was analyzed using weighted kappa test.Analyze the coincidence rate of CT diagnosis results and pathological results.Results 1.Chest There were no significant differences in gender,age,height,weight and body mass index among the four groups of chest patients(P> 0.05);In the four groups of patients,only one patient in group A developed mild urticaria adverse reactions after chest enhancement CT examination using iodine contrast agent.The consistency of the scores of the two radiologists was good.The kappa value ranged from 0.736(95% confidence interval: 0.54-0.933)to 0.809(95% confidence interval:0.65-0.968).The results of the four groups of subjective image scores were not statistically significant.Among the objective evaluation parameters,the noise(SD)in group A was the lowest(15.2 ± 4.6),the contrast noise ratio(CNR)and the CT value of pulmonary artery in group B were the highest(9.5 ± 3.1)and(215 ± 46.1)respectively,and the CNR in other groups were Group A(9.0 ± 5.3),Group D(7.1 ±2.5),Group C(6.2 ± 2.1).There was no statistical difference between the CT value of group D and group A.The volume CT dose index,dose length product,and effective dose of group D were significantly lower than those of group A.Among the four groups,the patients in group D received the lowest iodine dose(25848 ± 3014).Among the 216 cases,181 cases were confirmed by surgical resection or biopsy.Compared with the pathological results,there was no significant difference in the accuracy of imaging diagnosis among the four groups(P> 0.05).2.Upper abdomen There were no significant differences in gender,age,height,weight,and body mass index(BMI)in 120 patients undergoing enhanced CT of the upper abdomen(P>0.05);there were no adverse reactions of contrast agents after enhanced CT examination.The consistency of the subjective scores of the two radiologists on the image quality was good.The kappa values ??were 0.832,0.796,0845,and 0.861,respectively,and there was no statistical difference in the scores,both of which could meet the diagnostic needs.Among the objective evaluation indicators of image quality,group C had the highest CT value of abdominal aorta,CT value of liver parenchyma and noise,were(196.61 ± 23.34),(129.73 ± 14.44)and(24.41 ± 1.69),respectively.Comparing group D with group A,there was no significant difference in the objective evaluation indicators of image quality: CT value of abdominal aorta,CT value of liver parenchyma,CNR abdominal aorta,CNR liver parenchyma,and noise,no statistical significance(P> 0.05),but the radiation dose index CTDIvol decreased significantly by 28.61%.Among 120 cases,108 cases were confirmed by surgical resection or biopsy.Compared with the pathological results,there was no significant difference in the accuracy of imaging diagnosis among the four groups(P> 0.05).Conclusion Low-concentration iodine contrast agent(270mg I / ml)and low tube voltage(100k Vp)enhanced chest and upper abdomen CT examination can reduce the radiation dose and iodine of patients under the premise of ensuring the quality of CT images obtained to meet the needs of imaging diagnosis,thereby reducing the incidence of adverse reactions of iodine contrast agent. |
PDF Full Text Request