E-Flow显像技术在胎儿肺静脉超声检查中应用价值

【Abstract】wWw.shuoshilunwen.com Objective: At present, the main examining methods of fetal pulmonary veins are two-dimensional ultrasound (2-D) and color doppler flow imaging(CDFI). But it is difficult to examine fetal pulmonary veins by ultrasound because of its thin wall, all chamber and low velocities. Enhance flow(E-flow) is a novel displaying technology of blood flow which improves spatial and temporal resolution by applying composite pulse emission technique. In addition, E-flow is capable of distinguishing the blood flow and surrounding tissue and offers high sensitivity to detect low blood flow. Now the application of E-flow receives good results in displaying the capillary perfusion of shallow organ tumour, kidney essence and infection course. The objective of this study is applying E-flow imaging technology in ultrasound examination of pulmonary veins, comparing E-flow with 2-D and CDFI and analysing them. These will be explored such as the ultrasound examining methods of fetal pulmonary veins, the superiority and feasibility of E-flow, the normal fetal pulmonary venous internal diameter and flow velocity and their variation rule with gestational weeks.Methods: 408 fetuses were randomly recruited from these who came to our hospital for pregnancy examination. After excluding the fetuses with those conditions which may influence fetal developing, 332 normal fetuses were selected as studying object at last. These selected fetuses were between 12 and 40 weeks, with a mean of 26 weeks. The pregnant women were between 21 and 39 years old. Their meaning ages were 27years old. Theα-10 Color Ultrasonoscope with SSD9130 convex array probe (3.0-6.0 MHz) (ALOKA, Japan) was used. Fetal echocardiographic examination condition was used and the picture was adjusted to the best condition. The pregnant women lied horizontally or slopingly. Firstly, the fetal structure was examined in order using the obstetrical application procedure. Then, the structure and function of the fetal heart were evaluated comprehensively by fetal echocardiographic mode. These views were used such as the fetal abdomen horizontal view, four chamber view, three blood vessel trachea view, left and right outflow tract view, aortic arch and ductus arteriosus arch view, superior and inferior vena ca long axis view and other unstandard views.The examining methods of fetal pulmonary veins were as the following. The four chamber view was displayed by cutting the fetal chest horizontally. The probe was moved to fetal head and the bilateral pulmonary veins drainage into the left atrium was visualized with E-flow. The pulmonary venous internal diameter, peak systolic and diastolic flow velocity were measured at the hilum of the lung. When the fatel pulmonary veins were not displayed satiiedly at four chamber view, we could inspect them by cutting its chest lengthwisely. Descending aorta long axis view would be displayed by lengthwise view at the left fetal back. Then the probe was moved to display the left lung, the left atrium, part of the descending aorta and the left pulmonary veins drainage into the left atrium with E-flow. The long axis views of superior and inferior vena ca was displayed by lengthwise view at the right fetal back. Then the probe was moved to display the right lung, part of the long axises of superior and inferior vena ca and the right pulmonary veins were visualized with E-flow. The images and the datas above were stored in the hard disk of the appliance. In addition, the visualization of fetal pulmonary veins was observed with CDFI at above-mentioned views. These datas about visualization of fetal pulmonary veins such as the number and flow continuity of visualized pulmonary veins was recorded respectively by E-Flow,CDFI and 2-D.SPSS13.0 statistical software wes used. Visualization ratios of the pulmonary veins by three methods were compared using McNemar’sχ2 test. P-value less than 0.0167 was considered statistically significant. The data of pulmonary venous internal diameter and flow velocity were expressed as mean±SD. The internal diameter and flow velocity of left and right pulmonary venous were compared using a paired t-test. P-value less than 0.05 was considered statistically significant. The relationships between the pulmonary venous parameters and the gestational weeks were analyzed by double variable regression. P-value less than 0.05 was considered statistically significant.Results:1 The visualization ratios of the pulmonary veins and compare of the three methodsCDFI and E-flow were better than 2-D in visualization of pulmonary veins. The structure of fetal pulmonary veins wasn,t distinct and the flow condition couldn,t be visualized with 2-D. By CDFI, the fetal pulmonary venous flow was short of continuity and it is difficult to trace the location that pulmonary veins drainage to. By E-flow, the flow was continuous and tracing its drainage location was easy. The order of the three methods about pulmonary venous visualization ratios was E-flow,CDFI and 2-D from high to low for 12 to 22- week fetuses. The visualization ratios of E-flow and CDFI were higher than 2-D for 23 to 40-week fetuses(P<0.0167). But there was no difference between E-flow and CDFI(P=0.041>0.0167).2 The internal diameter and flow velocity of fetal pulmonary veinsAmong the 332 cases, there were 250 fetuses whose four pulmonary veins were visualized completely with E-flow. After calculating the 250 fetal pulmonary venous internal diameter and flow velocities, it indicated that the right and left pulmonary venous internal diameter and flow velocities increased with the gestational age. And there were linear relationship between internal diameter and weeks, flow velocities and weeks. The correlation ratios between internal diameter and gestational weeks were 0.6726 of right pulmonary veins, 0.6947 of left and their P value was less than 0.001. The correlation ratios between the systolic flow velocity and gestational weeks were 0.5912 of right pulmonary veins,0.5899 of left and their P value was less than 0.001. The correlation ratios between the diastolic flow velocity and gestational weeks were 0.5933 of right pulmonary veins,0.5428 of left and their P value was less than 0.001 too. The internal diameter and both the systolic and diastolic flow velocity of the fetal right pulmonary vein was significantly larger than the left (P<0.05).3 The fetal pulmonary venous flow spectrumThe normal fetal pulmonary venous flow spectrum included S we, D we and A we. S and D we were forward. The peak velocities of S we was faster than D we in most fetuses. The peak velocities of S we was slower than D we in few fetuses or they were equal. A we was forward in most fetuses and A we was absent or opposite in few fetuses.Conclusion:1 The visualization ratios of fetal pulmonary veins was higher with E-flow than with CDFI in early stage of the second trimester by echocardiography. The flow was continuous, no spillage and easy to trace the location of pulmonary venous drainage to with E-flow.2 Normal fetal pulmonary venous internal diameter and both the systolic and diastolic flow velocities increased with the gestational age. The internal diameter and the flow velocity of the fetal right pulmonary vein was larger than the left3 The normal fetal pulmonary venous flow spectrum included S we (we of ventricular systole), D we (we of ventricular diastole) and A we (we of atrial systole). Both S we and D we were forward. A we was forward usually and absent or opposite occasionally.4 The fetal pulmonary veins can be inspected earlier and faster with E-flow by pregnant ultrasonic examination with lung as sound window and total anomalous pulmonary venous drainage(TAPVD) can be screened.