构建正常胎儿心胸比Z评分模型

目的 构建正常胎儿心胸比（CTR）Z评分模型，包括横径比（CTR1）、周长比（CTR2）和面积比（CTR3）。方法 对954胎孕11~40⁺⁶周正常胎儿行产前超声检查，于标准切面测量CTR作为因变量，以胎体大小参数，包括孕周（GA）、双顶径（BPD）及股骨长度（FL）为自变量，行回归分析，获得CTR均数回归方程；并分析CTR残差，以确定CTR标准差的最佳回归方程；根据公式计算CTR Z评分。结果 正常胎儿CTR与GA、BPD及FL均呈正相关（r=0.74~0.86，P均<0.05）；胎儿CTR参数与胎体大小参数的最佳拟合方程均为直线回归方程。成功构建了基于胎体大小参数CTR均数的拟合回归方程；CTR残差分析结果提示CTR标准差不随胎体大小变化而改变，均为恒定值标准差；根据方程可计算正常胎儿CTR Z评分。结论 基于GA、BPD及FL建立的正常胎儿CTR Z评分模型可为产前评估胎儿发育提供参考。

Establishing Z-score models of normal fetal cardiothoracic ratio

Objective To establish Z-score models of normal fetal cardiothoracic ratio (CTR), including transverse diameter ratio (CTR1), perimeter ratio (CTR2) and area ratio (CTR3). Methods Totally 954 normal fetuses in 11-40⁺⁶ weeks gestation underwent prenatal ultrasound. CTR measured on the standard section were taken as the dependent variables, and the fetal somatic size parameters, including gestational age (GA), double apex diameter (BPD) and femur length (FL) were taken as the independent variables. Regression analysis was performed to obtain the regression equation of CTR mean. CTR residual was analyzed to determine the best regression equation for CTR standard deviation. Then Z-score of normal fetal CTR was calculated according to the formula. Results CTR of normal fetuses positively correlated with GA, BPD and FL (r=0.74-0.86, all P<0.05), and the best fitting equation of CTR parameters and fetal somatic size parameters were all linear regression equation. The fitting regression equations of CTR mean based on fetal somatic size parameters were successfully constructed. CTR residual analysis results showed that the CTR standard deviation did not change with fetal size, but present as constant standard deviation. Z-score of normal fetal CTR could be calculated according to the equation. Conclusion The established CTR Z-score models of normal fetal based on GA, BPD and FL could provide references for prenatal evaluation of fetal development.