Clinical Application Of Dual-source CT In Coronary Angiography With Contrast Medium Injection Based On Automated Tube Voltage Selection

In recent years,with the rapid development of China’s economy,people’s living conditions have been constantly improved.Great changes of dietary structure results the increasing morbidity and mortality of hyperlipemia,hypertension,diabetes and other related diseases,which are the causes of coronary heart increase year by year.Under this background,it is very important to choose the appropriate examination method for early detection and diagnosis of coronary heart disease,so as to benefit for preventing and intervening the occurrence and development of the disease.At present,coronary angiography is still the "Gold standard" for clinical diagnosis.However due to the invasiveness,high cost and high risk,coronary angiography is hardly accepted by patients.Compared with coronary angiography,the advantages of low cost,non-invasiveness,safety,and high comfort which cause high compliance for patients make coronary artery CT angiography,the so-called"Gatekeeper”of invasive examination and treatment,to be the first choice for clinical screening.Although application of coronary artery CT angiography increases rapidly,the key problem that how to control the effective radiation dose and the contrast dose on the premise of ensuring the image quality calls for immediate solution.The automatic tube voltage selection technique of 3rd generation dual source CT can significantly reduce the radiation dose while maintaining image quality meanwhile adjusting the dose of contrast agent according to the tube voltage.There are many studies in China which show that the 3rd generation dual-source CT(DSCT)is feasible,but there is no clinical research on the contrast injection protocol based on the DCT.At present,in the clinical practice of coronary artery CT angiography,there is a lack of individualized and standardized contrast injection protocol.In this study,we will compare the contrast agent injection scheme based on automatic tube voltage technology with the previous one based on body mass.The purpose of this study is to explore the clinical application value of contrast agent injection based on automatic tube voltage selection technology,and to verify the possibility to reduce radiation dose and contrast agent dosage in the context of the same image quality.Objective:To explore the clinical value of auto-tube voltage controlled contrast medium injection based on 3rd generation dual source CT coronary angiography.Materials and methods:Patients with suspected coronary heart disease were prospectively enrolled from March to December,2019 at Shandong Provincial Hospital and coronary CT angiography(CCTA)images were acquired from 220 patients,including 107 male,113 female,aged from 34 to 82 years.Patients were divided into experimental and control groups with the random number table.In experimental group(113 patients),automatic tube voltage selection technology was used,the contrast agent dosage was set according to tube voltage.The injection time was 10 s;In control group(107 patients),tube voltage and contrast agent dosage were set according to weights.The injection time was 12 s.Images were acquired by ECG gating using the 3rd generation dual source CT(DSCT)with intravenous injection of 350 mg/L contrast medium,followed up with saline of the same dose.Interclass correlation coefficient(ICC)was used to evaluate the individual bias of raters.The rank sum test was used to evaluate the group-level differences of subjective image quality and contrast agent dosage.The t-test was used to evaluate the group-level differences of objective image quality and effective radiation dose(ED),Results:The noise of aortic root in the two groups were(27±4),(2615)HU,respectively,with no statistical difference(t=1.017,P=0.284).All ICC values were morethan 0.5 indicating good correlation batween 2 raters.The objective image quality score was no significant differences(P>0.05).The subjective image quality scores of the two groups were 1.15± 0.10 and 1.18±0.12,respectively,with no statistical difference(Z=-0.231,P=0.818).The ED value(2.2±0.6)mSv of experimental group was statistically lower than that of control group(4.6±1.8)mSv(t=-13.107,P<0.001);the contrast dosage(35±7)ml of experimental group was statistically lower than that of control group(46±6)ml(t=-8.699,P<0.001).Conclusion:The novel scanning protocol with auto-tube voltage based contrast agent setting is more convenient and practical with reduced radiation dose and contrast dose,while maintaining image quality.