| Background and ObjectiveThe superior mesenteric artery is the main blood supply artery of the intestinal tract.Its pathological changes can seriously affect the structure and function of the intestinal tract,and even threaten the safety of life.For example,acute mesenteric ischemia is mainly caused by superior mesenteric artery thrombosis and embolism,with a mortality rate of 30%-95%.At present,because of its advantages of convenience,multi angle observation and high accuracy,multi row spiral CT angiography has become the first choice for the superior mesenteric artery angiography.However,with the wide application of multi row spiral CT,the adverse reactions caused by iodine contrast agent get more and more attention.According to the research statistics at home and abroad,the incidence of adverse reactions of contrast agent is as high as 0.34%-3.13%,among which contrast nephropathy has become the third major medical cause of renal failure.The main method to reduce the adverse reactions of contrast agent is to reduce the concentration and dose of contrast agent,so reducing the concentration and dose of contrast agent has become the focus of scholars at home and abroad,while the research on injection rate is less.It is generally believed that the increased injection rate will increase the risk of contrast agent extravasation.Therefore,domestic and foreign researches mostly pursue low-speed injection of contrast agent.However,in practical application,the injection scheme of contrast agent should be optimized reasonably.When the injection rate is properly increased,reducing the concentration of contrast agent will not change the image quality,and will not increase the risk of adverse reactions of contrast agent.Some studies have shown that the determinant of the degree of vascular enhancement is the iodine delivery rate(IDR).The increase of contrast injection rate will increase the intravascular iodine flow rate and enhance the effect of vascular enhancement.Therefore,when the contrast concentration is reduced,the injection rate can be properly increased to maintain the iodine flow rate,so as to ensure the image quality.The purpose of this study is to explore the application of low concentration and low dose contrast agent combined with high injection rate in the imaging of superior mesenteric artery,so as to ensure the image quality and reduce the harm brought by contrast agent as much as possible.Materials and methodsFrom January,2018 to August,2019,a total of 300 patients underwent CTA examination of superior mesenteric artery in our hospital,in which 162 males and 138 females were included,aged 33-77,with an average age of 53.83 ± 9.18.The patients were randomly divided into two groups for A(high concentration group)and B(low concentration group).Group A:Omnipaque 350mg/ml,injected at a rate of 4ml/s;Group A was divided into A1,A2,A1 group 80ml,A2 group 70ml according to the injection dose;Group B:Visipaque 270 mg/ml,70ml contrast agent,Group B according to different injection rates divided into B1(4ml/s),B2(4.5ml/s),B3(5ml/s),There were 60 cases in each group;the body mass index(BMI)was controlled in the range of 18.0～25.0 kg/m2;Exclusion criteria:Patients with previous iodine contrast agent allergy,diabetes,severe heart and renal insufficiency,and diseases affecting abdominal blood flow.All patients were scanned on the Siemens dual source CT machine,the tube voltage was 120kv,and the current was selected by automatic tube current modulation technology;iterative reconstruction by SAFIRE and post-processing of the original data;The CT diagnosis results of atherosclerotic plaque formation,artery dissection,artery embolism,nutcracker syndrome and other diseases in this study were recorded and compared with those of DSA or surgery;the CT values of superior mesenteric artery in each group were measured;assessing the image quality by two deputy doctors and above;The total amount of iodine in each group was calculated.The total amount of iodine in each group is the product of the injection dose and the concentration of the contrast agent;and the incidence of adverse reactions in each group was measured.Using the 4-point method to assess image evaluation:the superior mesenteric artery trunk from the abdominal aorta is the trunk,and its lower branches are defined as the main branches,and the remaining branches are the distal branches:1 point,poor image quality,clear display of the trunk,unclear development of the main branches,unsmooth vascular edges,visible respiratory motion artifacts;2 point,good image quality,clear display of the trunk and main branches,good vascular filling No development of distal branches,smooth edges of blood vessels,no respiratory movement artifacts;3 points,good image quality,clear development of main branches,smooth edges of blood vessels,good filling of blood vessels,no respiratory movement artifacts,unclear development of distal branches;4 points,good image quality,clear development of main branches,main branches and distal branches,smooth edges of blood vessels,full of blood vessels Good.Two deputy senior radiologists read the film respectively,and the final results were agreed.SPSS 21.0 software was used for data statistics,and the measurement data was represented by X ± S.Kruskal Wallis test was used for gender comparison and image subjective score comparison of three groups;ANOVA was used for age and BMI comparison of three groups;LSD-t test was used for CT value comparison,and Dunnett’s T3 test was used for non-compliance.The test level was 0.05.If P<0.05,there were statistically significant difference.In addition,the results of disease diagnosis were expressed with positive rate and accuracy rate.ResultsIn this study,there were 110 cases of atherosclerotic plaque formation,19 cases of arterial dissection,9 cases of arterial embolism,6 cases of arterial thrombosis and 11 cases of nutcracker syndrome.The total number of patients diagnosed by CT was 155,the positive rate of patients was 51.7%,compared with DSA or surgical operation,the diagnostic accuracy of CT was 100%;There were no statistically significant differences in gender,age,and BM3 between the five groups(P>0.05).The CT values of A1,A2,B1,B2,B3 groups are(338.46±38.10)HU,(332.44±41.91)HU,(296.09±24.77)HU,(313.32±29.43)HU and(345.05±39.10)HU.Compared A1 with A2,the difference was not statistically significant(P>0.05);There was no significant difference in CT values between the three groups A1,A2,and B3(P>0.05),and the differences between the other groups were statistically significant(P<0.05).The five groups’ image quality scores are A1(3.6±0.5),A2(3.5±0.7),B1(2.7±0.7),B2(3.1±0.8)and B3(3.5±0.6),and A1>A2>B3>B2>B1,A1,A2 and B3 were not statistically significant(P>0.05)when Pair-wise comparison.The rest of the groups were statistically significant(P<0.05);Compared with group A1,the dose of contrast agent of A2 was reduced by 10 ml,the total amount of iodine was 24.5g and 28.0g respectively,and the total amount of iodine was reduced by 12.5%,the total iodine in the A1 and B3 groups were 28.0g and 18.9g,respectively,and the iodine consumption in the low-concentration and low-dose groups decreased by 32.5%;There were 2 cases of mild adverse reactions in group A1 and no adverse reactions in other groups.ConclusionLow-dose and low-concentration contrast agents(Visipaque 270mg/ml,70ml)combined with high injection rate(5ml/s)can reduce the total iodine and ensure the image quality,to achieve the purpose of reducing the total iodine and reducing the harm from contrast agents.The whole research has clinical significance. |
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