应用二维斑点追踪成像技术评估孕周及心尖方向对中晚孕期正常胎儿左心房应变的影响

Impact of gestational age and apex orientation on left atrial strain assessed by two-dimensional speckle tracking imaging in normal fetuses during the second and third trimesters

目的探讨二维斑点追踪成像技术(2D-STI)在评估胎儿左心房应变3个时相功能中的应用价值、左心房应变3个时相功能与孕周的相关性以及该技术在胎儿心脏检查实际应用中对心尖方向是否存在角度依赖性。方法选取2021年11月至2022年1月在浙江大学医学院附属邵逸夫医院超声科接受胎儿超声心动图检查的正常妊娠中、晚孕期单胎胎儿180例,共获取611个不同心尖角度胎儿四腔心动态图像,应用2D-STI分析获得左心房储存期峰值应变(LASr_ED)、管道期峰值应变(LAScd_ED)和收缩期峰值应变(LASct_ED),其中有11例共计32个动态图像2D-STI分析心房收缩的起始点不能识别,无法区分心房收缩期与管道期。选取169例四腔心切面心尖方向为10:30~1:30能良好追踪并识别左心房3个时相功能的病例与孕周进行线性回归分析。选取能良好追踪并识别左心房3个时相的动态图像579个,其中中孕期18~24周的图像126个、25~28周的图像190个,晚孕期29~32周的图像150个、33~36孕周的图像113个;按不同心尖方向分成4组,组1心尖方向10:30~1:30,组2心尖方向1:30~4:30,组3心尖方向4:30~7:30,组4心尖方向7:30~10:30;同一孕期不同心尖方向组间应变参数比较采用F检验和LSD-t检验。结果2D-STI能够成功追踪并识别胎儿左心房3个时相应变的比例为94.76%(579/611)。线性回归分析显示,LASr_ED随孕周增加而减小(r=-0.32,P<0.001),LAScd_ED随孕周增加而增大(r=0.15,P<0.05),LASct_ED随孕周增加而减小(r=-0.35,P<0.001)。中孕期18~24周、25~28周不同心尖方向4组左心房3个应变参数比较,差异均无统计学意义(P均>0.05);晚孕期29~32周不同心尖方向4组胎儿的LASr_ED总体均数比较,差异存在统计学意义(F=2.759,P=0.044);晚孕期33~36周不同心尖方向4组胎儿的LASr_ED及LAScd_ED总体均数比较,差异存在统计学意义(F=2.919,P=0.037;F=4.234,P=0.007)。4组间两两比较,同一孕期组1和组3的LASr_ED、LAScd_ED及LASct_ED比较,差异均无统计学意义(P均>0.05),同一孕期组2和组4的LASr_ED、LAScd_ED及LASct_ED比较,差异均无统计学意义(P均>0.05)。结论中晚孕期正常胎儿左心房应变参数LASr_ED、LASct_ED与孕周呈弱负相关,LAScd_ED与孕周呈极弱正相关。2D-STI在正常妊娠中孕期胎儿心脏左心房应变定量分析中无心尖角度依赖性,在正常妊娠晚孕期胎儿心脏左心房应变定量分析中LASr_ED及LAScd_ED存在一定的心尖角度依赖性。选择轴向或横向四腔心切面作为统一图像采集标准,能更加准确地获得胎儿左心房应变参数,为胎儿心脏功能的定量评估和连续性监测提供依据。

Objective To assess the application value of two-dimensional speckle tracking imaging(2D-STI)in the evaluation of fetal left atrial strain in three phases,and to explore the correlation between the three phases of left atrial strain and gestational age,and whether the technique has angular dependence on the apex orientation in fetal heart examination.Methods A total of 180 normal singleton fetuses in the second and third trimesters who underwent fetal echocardiography at the Department of Diagnostic Ultrasound&Echocardiography,Sir Run Run Shaw Hospital,Zhejiang University College of Medicine from November 2021 to January 2022 were selected.A total of 611 fetal four-chamber view video clips with different apex angles were obtained.2D-STI analysis was used to obtain the peak storage strain(LASr_ED),peak pipeline strain(LAScd_ED),and peak systolic strain(LASct_ED)of the left atrium.2D-STI could not identify the onset of atrial contraction in 11 fetuses(32 dynamic images),and could not distinguish the atrial contraction phase from the conduit phase.Linear regression analysis was used to analyze the relationship between gestational age and 2D-STI parameters in patients in whom the three phases of left atrial strain with the apex orientation of 10:30 to 1:30 in the four-chamber view could be well tracked and identified.A total of 579 dynamic images with good tracking and recognition of the three phases of left atrial strain were selected,including 126 during 18-24 gestational weeks,190 during 25-28,150 during 29-32,and 113 during 33-36.The patients were divided into four groups according to the apex orientation:group 1(apex orientation:10:30-1:30),group 2(1:30-4:30),group 3(4:30-7:30),and group 4(7:30-10:30).The F test and LSD-t test were used to compare the left atrial strain parameters between different groups of normal fetuses in the same gestational weeks.Results 2D-STI could successfully track and identify the three temporal variations of the left atrium in 94.76%(579/611)of fetuses.LASr_ED and LASct_ED decreased with the increase of gestational age(r=-0.32,P<0.001;r=-0.35,P<0.001),while LAScd_ED increased with the increase of gestational age(r=0.15,P<0.05).There was no statistical difference in the three strain parameters of the left atrium in different apex orientations among the four groups at 18-24 gestational weeks and 25-28 gestational weeks(all P>0.05).There were significant differences in LASr_ED among the four groups at 29-32 gestational weeks(F=2.759,P=0.044).There were significant differences in LASr_ED and LAScd_ED among the four groups at 33-36 gestational weeks(F=2.919,P=0.037;F=4.234,P=0.007).Pairwise comparisons were then made among the four groups.There were no significant differences in LASr_ED,LAScd_ED,and LASct_ED between group 1 and group 3 during the same gestational weeks(all P>0.05),and in LASr_ED,LAScd_ED,and LASct_ED between group 2 and group 4 during the same gestational weeks(all P>0.05).Conclusion LASr_ED and LASct_ED of normal fetuses in the second and third trimesters are weakly negatively correlated with gestational age.There is a very weakly positive correlation between LAScd_ED and gestational age in normal fetuses in the second and third trimesters.2D-STI has no apex angle dependence in the practical application of fetal left atrial strain in the second trimester,but has certain apical angle dependence in the third trimester.Choosing axial or transverse four-chamber heart view as the unified image acquisition standard can help obtain fetal left atrial strain parameters more accurately,and provides a basis for quantitative assessment and continuous monitoring of fetal cardiac function.