SonoNT建立正常胎儿颈项透明层Z评分数据模型的研究

Z-score analysis of nuchal translucency in normal fetuses with semi-automated software

目的探讨孕11～13+6周正常胎儿颈项透明层(NT)与胎儿生物学生长参数的相互关系,从而量化NT的Z评分(Z-score)参考范围。方法应用超声检测1 000例孕龄为11～13+6周胎儿的顶臀径(CRL)和孕周(GA),应用SonoNT半自动测量软件测量NT,以CRL、GA为自变量,NT作为因变量建立最佳模型,再分析标准差(SD)与自变量CRL、GA的关系,运用公式计算Z-score的参考范围。结果直线回归方程能够很好地反映胎儿生物学生长参数CRL、GA与胎儿NT之间的相关性,NT的SD随自变量增大而增大,也呈线性关系,运用绝对残差的加权回归消除SD的异方差性,建立直线回归模型,并据此计算出不同CRL、GA范围时胎儿NT的Z-score参考值。结论通过胎儿CRL、GA计算NT的Z-score正常参考范围,可为胎儿NT测量提供更加精准的参考标准。

Objective To explore the correlation of nuchal translucency(NT)and biometric parameters in fetuses at11~13^+6gestational ages(GA)and develop the Z-score reference ranges for NT.Methods A retrospective study of1000fetuses at11~13^+6GA were underwent.Fetal biometric parameters included crown-rump length(CRL)and GA.NT was measured in SonoNT.Nomal Z-score ranges were developed for NT using CRL and GA as independent variables.These were accomplished by using first standard regression analysis and then weighted regression of absolute residual values for each parameter in order to adjust for inconstant variance.Results Linear regression model had a excellent description of the correlations between NT and independent variables(CRL and GA).Heteroscedasticity of standard deviation(SD)with independent variables also could be modeled with a simple liner regression.According to these equations,NT Z-score=(the actual measurement of NT-predicted NT)/predition SD.Conclusion Normal reference ranges and Z-score for NT have been provided.These normative data may be an useful tool in the assessment of fetal NT.