Study on Z-Score Model of Normal Fetal Thymus

doi:10.12280/gjfckx.20211093

Abstract

Abstract:

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 two-dimensional 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.

Key words: Fetus, Thymus gland, Ultrasonography,prenatal, Z-score, Prediction model

GU Kai-li, FENG Tao, TIAN Li, DENG Miao-miao, WANG Li-qi. Study on Z-Score Model of Normal Fetal Thymus[J]. Journal of International Obstetrics and Gynecology, 2022, 49(3): 340-344.

Figures/Tables 9

References 16

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参数	回归方程	相关系数（r）	决定系数（R²）	F	P
横径	Ŷ=0.109×孕周-0.570	0.873	0.762	1 952.164	<0.001
前后径	Ŷ =0.056×孕周-0.389	0.793	0.629	1 036.009	<0.001
面积	Ŷ =0.224×孕周-3.639	0.826	0.683	1 312.565	<0.001
周长	Ŷ =0.293×孕周-1.176	0.815	0.665	1 210.463	<0.001

参数	回归方程	相关系数（r）	决定系数（R²）	F	P
横径	Ŷ=0.109×孕周-0.570	0.873	0.762	1 952.164	<0.001
前后径	Ŷ =0.056×孕周-0.389	0.793	0.629	1 036.009	<0.001
面积	Ŷ =0.224×孕周-3.639	0.826	0.683	1 312.565	<0.001
周长	Ŷ =0.293×孕周-1.176	0.815	0.665	1 210.463	<0.001

参数	回归方程	相关系数（r）	决定系数（R²）	F	P
横径	Ŷ =0.042×BPD-0.450	0.868	0.753	1 859.771	<0.001
前后径	Ŷ =0.021×BPD-0.339	0.794	0.631	1 041.447	<0.001
面积	Ŷ =0.086×BPD-3.469	0.831	0.691	1 364.798	<0.001
周长	Ŷ =0.111×BPD-0.829	0.808	0.653	1 148.601	<0.001

参数	回归方程	相关系数（r）	决定系数（R²）	F	P
横径	Ŷ =0.042×BPD-0.450	0.868	0.753	1 859.771	<0.001
前后径	Ŷ =0.021×BPD-0.339	0.794	0.631	1 041.447	<0.001
面积	Ŷ =0.086×BPD-3.469	0.831	0.691	1 364.798	<0.001
周长	Ŷ =0.111×BPD-0.829	0.808	0.653	1 148.601	<0.001

参数	回归方程	相关系数（r）	决定系数（R²）	F	P
横径	Ŷ =0.051×股骨长-0.130	0.869	0.755	1 881.858	<0.001
前后径	Ŷ =0.026×股骨长-0.147	0.781	0.609	951.243	<0.001
面积	Ŷ =0.105×股骨长-2.772	0.828	0.686	1 332.465	<0.001
周长	Ŷ =0.138×股骨长-0.048	0.819	0.653	1 238.176	<0.001