| RESEARCH BACKGROUNDThe incidence and mortality of cardiovascular disease in European and American countries are very high. In recent years, there is a trend of increasing year by year in developing countries, such as China. In the majority of low-income and middle-income countries, the rapid rise in cardiovascular disease is due to the economic and social changes, as well as with lifestyle related risk factors, also the mortality of cardiovascular disease in various regions of China, also very different. Different incidence rate, sick and death rates reflect the different levels of risk factors, according to the World Health Organization estimates that about 30% of annual global deaths are due to cardiovascular diseases. Therefore, it is quite a number of suspected cardiovascular disease person needs clinical assessment, and more shows a trend of younger age, so early diagnosis for cardiovascular disease is very important. Interventional cardiac angiography is a in X ray will contrast agent into the blood vessels in the heart, the visualization can be achieved through the digital processing process, after this as the CVD disease diagnosis standard, it does not matter inspection fees and security terms, great defects. The growing popularity of the multi-slice spiral CT due to the fast speed, the advantages of wide coverage, greatly reducing the scan time, the coronary CT angiography (CCTA) become a reality CCTA as a simple, fast, and non intrusive inspection method, to a large number of patients accepted by many studies also confirmed the higher accuracy and clinical value. But with the popularization, brought two serious problems, one is the radiation dose is two, the amount of contrast agent.PURPOSEThe purpose of this study is to investigate the prospective ECG triggering technology (by reducing the tube current and tube voltage, reasonable configuration) and low contrast agent dosage in coronary CT angiography in clinical application value, and to a greater degree reduce subjects radiation dose, reduce the contrast agent risk of harm.METHODThe third people’s hospital outpatient or hospitalized suspected coronary heart disease, and selected 200 cases to determine the examination of patients (age 45-65), using the United States GE64 slice CT (US GE64 VCT XT) instrument coronary angiography (1) is divided into A, B two groups (100 cases each), all subjects with a high concentration of nonionic contrast agent Shuangbei iohexol (100ml:35g (Ⅰ)), A group contrast agent 1.2ml/kg body weight, B group contrast agent of 0.8ml/kg body weight, injection rate according to the same subjects were calculated (V= gamma (kg), wherein X weight V as the injection rate of contrast medium, gamma =0.07ml/kg.s) (2) A, B two groups were divided into A1, A2 and B1, B2 four groups, the number of patients in each group were 50 people, including A1 and B1 group as the control group using the back door control (retrospective ECG gating) coronary artery scan technology, A2 and B2 group to take a low dose (forward ECG trigger) technology scanning (and according to the body mass index (BMI= weight) (Kg)/ height 2 (M 2), using the heart of the intelligent Ma scan) BMI.Two rich experience diagnosis observer (a radiologist) in accordance with the double blind method first on coronary images were graded screened C above the level of the image is evaluated, in accordance with international common coronary 15 segmentation method, the Likert4 level image quality score method to accord with the standard of image quality assessment scores, accurately record, the first step is to calculate a, B two groups of contrast agent dosage and image noise, image quality scores, and carries on the comparative analysis, and then on the A1, A2 and B1, B2 by different scanning way to examine the radiation dose and image noise, image quality scores were compared between, and statistical analysis.RESULTSThe topic selected 200 patients, the number of patients successfully completed coronary angiography (CTA) examination of 194 cases, the success rate was 97%, the ultimate success of the reconstructed image are consistent with clinical diagnostic requirements. (1) Comparison of the amount of contrast agent, the statistics show, A group, the average amount of 82.65ml, group B average dosage of 54.3ml, group B with an average contrast ratio of group A was reduced by about 34.3%. The average degree of two sets of image enhancement (aorta, LM, LAD-p, LCX-p, RCA-p) five parts of CT, A group of images was 354.48 ± 35 (HU), the image group B was 321.8 ± 29 (HU), between the two groups p-value is 0.064> 0.05, the image quality assessment scores in group a was 3.2 ± 0.8, group B was 3.0 ± 0.9, p-value between the two groups is 0.83> 0.05, image noise (standard deviation SD) A group was 28.9 ±11.9 (HU), group B was 29.9 ± 11.5, between the two groups (t= 0.57, p-value of 0.49> 0.05), group B than in group a slight image noise increased, but the overall image quality score was not statistically significant, both to meet the requirements of clinical diagnosis; (2) to conventional scan parameters set (A1, B1) and low-dose group (A2, B2) of the resulting image coronary calculated by comparing patients accepted effective radiation dose, statistical results A1 ED group is 15.6 ± 2.2 (mSv), A2 group was 4.3 ±1.4 (mSv), between the two groups (t= 24.6, p-value of 0.005 <0.05), A2 ED group compared with the value Al was significantly lower, reducing the rate of about 79.7%, B1 group ED value of 14.8 ± 2.5 (mSv), B2 group was 4.2 ± 1.5 (mSv), between the two groups (t= 22.8, p-value of 0.005<0.05), B2 ED group was significantly lower than the Bl group, a reduction of about 78.2%, the difference was statistically significant. Image noise (standard deviation SD) Al group was 29.2 ± 12.3 (HU), A2 group was 28.7 ±11.7 (HU), B1 group was 30 ± 10.8 (HU), B2 group was 29.8 ± 12.5 (HU), A1 and A2 between groups (t= 0.57, p-value of 0.65> 0.05) between B1 and B2 group (t= 0.65, p-value of 0.58> 0.05). Image quality score A1 group was 3.2 ± 0.8, A2 group was 2.9 ± 0.9, between the two groups (t= 0.24, p-value of 0.88> 0.05), B1 group was 3.1 ± 0.8, B2 group was 2.9 ± 0.7, between the two groups (t= 0.26, p-value of 0.83> 0.05). Comparison between groups image noise, quality scores p values were greater than 0.05, not statistically significant.CONCLUSION1. A, B two groups of contrast agent dose and image noise, the mass fraction of comparison, reasonable to reduce the amount of contrast agent and application in the drug delivery rate according to the weight of the optimization strategy can meet the requirements of the clinical diagnosis of coronary artery imaging;2. Low dose group A2 and B2 by conventional scanning A1, B1 group coronary image and effective radiation dose, image noise and signal-to-noise ratio (objective) and comparison of image quality scores (subjective) that low dose group of scanning can be more greatly reduce the radiation dose to the patient, and to and after processing the reconstructed image can reach the requirements of clinical diagnosis.MEANINGThe "double low" scanning scheme, both patients with contrast medium, the total amount is reduced, reduce the incidence of contrast agent from damaging the risk, and to a greater extent reduce patients received effective radiation dose, effectively reduce the occurrence of cancer risk, and reconstruct the image can also be to meet the requirements of clinical diagnosis, to better reflect the imaging optimization and humanity. |
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