正常胎儿胸腺Z评分模型的研究

Study on Z-Score Model of Normal Fetal Thymus

目的:探讨胎儿胸腺横径、前后径、面积及周长随孕周增加的变化规律,建立20~38周正常胎儿胸腺Z评分模型。方法:随机抽取2020年9月—2021年5月在河南中医药大学第三附属医院进行常规产检的单胎孕妇612例,测量胎儿胸腺横径、前后径、面积和周长,根据各测量值与孕周、双顶径(biparietal diameter,BPD)、股骨长的相关系数筛选评估胎儿胸腺大小的最佳指标,建立胎儿胸腺基于孕周、BPD、股骨长最佳预测回归方程和预测标准差(standard deviation,SD)回归方程,并根据公式Z=(胸腺实际测量值-预测值)/预测SD构建Z评分模型。结果:胎儿胸腺横径、前后径、面积及周长的二维测量值均随着孕周的增加而增加,与孕周呈正相关(P<0.001);其中胸腺横径与孕周的相关性最高(r=0.873,P<0.001)。胎儿胸腺横径与孕周、BPD、股骨长最佳拟合方程均为线性。成功建立了胎儿胸腺横径的预测回归方程和预测标准差回归方程,计算所得的Z值经Shapiro-Wilk检验均满足正态分布(P>0.05)。结论:胸腺横径为评估正常胎儿胸腺大小的最佳二维指标,建立的胎儿胸腺横径的Z评分模型为产前评估胎儿胸腺发育情况及早发现胸腺发育异常相关疾病提供了依据。

Objective:To investigate the changes of fetal thymus transverse diameter,anterior and posterior diameter,area and circumference with gestational age(GA),and to establish the Z score model of normal fetal thymus from 20 to 38 weeks.Methods:From September 2020 to May 2021,612 single pregnant women who underwent routine prenatal examinations in the Third Affiliated Hospital of Henan University of Traditional Chinese Medicine were randomly selected.The transverse diameter,anterior and posterior diameter,area and circumference of the fetal thymus were measured.According to the correlation coefficients between the measured values and GA,biparietal diameter(BPD)and femur length(FL),the optimal indexes for evaluating fetal thymus size were selected.The optimal prediction regression equation and prediction standard deviation(SD)regression equation of fetal thymus were established based on GA,BPD and FL,and the Z-score model was constructed according to the formula Z value=(actual measured thymus value-predicted thymus value)/predicted SD.Results:The twodimensional measurements of fetal thymus increased with the increase of GA,which was significantly positively correlated with GA(P<0.001).The correlation between thymus diameter and GA was the highest(r=0.873,P<0.001).The best fitting equations of fetal thymus diameter with GA,BPD and FL were linear.The predicted regression equation and the predicted standard deviation regression equation of fetal thymus diameter were established successfully,and the Z-values calculated by Shapiro-Wilk test satisfied normal distribution(P>0.05).Conclusions:Thymus transverse diameter is the best two-dimensional index to evaluate normal fetal thymus size,and the Z-score model of fetal thymus transverse diameter provides a basis for prenatal evaluation of fetal thymus development and early detection of diseases related to abnormal thymus development.