Lee W, Deter R L, Sameera S, Espinoza J, Gonçalves L F, Romero R
Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, Royal Oak, USA.
Ultrasound Obstet Gynecol. 2008 May;31(5):520-8. doi: 10.1002/uog.5302.
To develop individualized growth assessment (IGA) standards for upper (ThC(u)) and middle (ThC(m)) fetal thigh circumferences using three-dimensional ultrasonography.
A prospective, longitudinal sonographic study of 30 fetuses was performed beginning at 18 weeks' menstrual age. Second-trimester sonographic parameters were measured from three-dimensional volume data to establish IGA standards. Normal infant growth outcomes were confirmed using modified Neonatal Growth Assessment Scores (m(3)NGAS(51)). ThC(u) and ThC(m) were studied in more detail. Rossavik growth model specification procedures, based on the slopes of the second-trimester growth curves, were developed for both ThC(u) and ThC(m). Third-trimester growth trajectories and birth measurements were subsequently predicted for these parameters. Percentage deviations during the third trimester and percentage differences at actual birth age were used to compare observed and predicted measurements. The 95% ranges for Growth Potential Realization Index (GPRI) values for both types of thigh circumference were determined. Values for m(3)NGAS(51) using GPRI(ThC(u)), GPRI(ThC(m)) and GPRI(ThC(o)) (original method) were compared.
The 30 newborns had no postnatal evidence of abnormal growth. Two examiners demonstrated a satisfactory measurement bias of mean +/- SD 2.1 +/- 3.6 (95% limits of agreement,-4.9 to 9.1)% for ThC(m) and 3.3 +/- 4.1 (95% limits of agreement,-4.8 to 11.4)% for ThC(u). Rossavik functions fitted parameter trajectories well, with mean R(2) values of 99.5 +/- 0.4% for ThC(u) and 99.6 +/- 0.3% for ThC(m). By fixing coefficients k at their mean values, their respective fits did not change, and the variabilities of coefficients c and s were significantly reduced. For ThC(u), coefficient c was significantly related to the second-trimester slope (R(2)=98.6%), as was s to c(R(2)=91.0%). For ThC(m), coefficient c was significantly related to the second-trimester slope (R(2)=98.6%), as was s to c(R(2)=85.6%). Third-trimester growth trajectories, derived from second-trimester slopes for individual fetuses, had third-trimester deviations of 0.07 +/- 3.7% for ThC(u) and-0.04 +/- 3.7% for ThC(m). Percentage differences at birth age were 16.8 +/- 10.2% for ThC(u) and 8.9 +/- 9.5% for ThC(m). With correction for systematic overestimations, the mean GPRI values were 103.7 (95% range, 90-121)% for ThC(u) and 101.6 (95% range, 88-118)% for ThC(m). Corresponding mean +/- SD m(3)NGAS(51) values, using GPRI(ThC(u)), GPRI(ThC(m)) and GPRI(ThC(o)), were 203 +/- 11%, 201 +/- 10% and 200 +/- 9%, respectively.
Fetal thigh circumference can be measured reliably and evaluated using standard IGA methods. Both ThC(u) and ThC(m) give similar results in the third trimester but neonatal thigh circumference predictions are improved by using ThC(m). Corresponding GPRI(ThC(m)) values are closer to the ideal value of 100% and can be used in m(3)NGAS(51) calculations for assessment of neonatal growth outcome.
利用三维超声制定胎儿大腿上围（ThC(u)）和大腿中围（ThC(m)）的个体化生长评估（IGA）标准。
对30例胎儿进行前瞻性纵向超声研究，从月经龄18周开始。从三维容积数据中测量孕中期超声参数以建立IGA标准。使用改良新生儿生长评估评分（m(3)NGAS(51)）确认正常婴儿生长结局。对ThC(u)和ThC(m)进行更详细的研究。基于孕中期生长曲线斜率，为ThC(u)和ThC(m)制定了罗萨维克生长模型规范程序。随后预测这些参数的孕晚期生长轨迹和出生时测量值。使用孕晚期的百分比偏差和实际出生年龄的百分比差异来比较观察值和预测值。确定了两种大腿围的生长潜力实现指数（GPRI）值的95%范围。比较了使用GPRI(ThC(u))、GPRI(ThC(m))和GPRI(ThC(o))（原方法）的m(3)NGAS(51)值。
30例新生儿出生后无生长异常证据。两名检查者对ThC(m)的测量偏差均值±标准差为2.1±3.6（95%一致性界限，-4.9至9.1）%，对ThC(u)的测量偏差均值±标准差为3.3±4.1（95%一致性界限，-4.8至11.4）%。罗萨维克函数能很好地拟合参数轨迹，ThC(u)的平均R(2)值为99.5±0.4%，ThC(m)的平均R(2)值为99.6±0.3%。通过将系数k固定在其均值，各自的拟合未改变，且系数c和s的变异性显著降低。对于ThC(u)，系数c与孕中期斜率显著相关（R(2)=98.6%），s与c也显著相关（R(2)=91.0%）。对于ThC(m)，系数c与孕中期斜率显著相关（R(2)=98.6%），s与c也显著相关（R(2)=85.6%）。根据个体胎儿孕中期斜率得出的孕晚期生长轨迹，ThC(u)的孕晚期偏差为0.07±3.7%，ThC(m)的孕晚期偏差为-0.04±3.7%。出生时的百分比差异，ThC(u)为16.8±10.2%，ThC(m)为8.9±9.5%。校正系统性高估后，ThC(u)的平均GPRI值为103.7（95%范围，90 - 121）%，ThC(m)的平均GPRI值为101.6（95%范围，88 - 118）%。使用GPRI(ThC(u))、GPRI(ThC(m))和GPRI(ThC(o))时，相应的平均±标准差m(3)NGAS(51)值分别为203±11%、201±10%和200±9%。
胎儿大腿围可通过标准IGA方法可靠测量和评估。ThC(u)和ThC(m)在孕晚期给出相似结果，但使用ThC(m)可改善新生儿大腿围预测。相应的GPRI(ThC(m))值更接近理想值100%，可用于m(3)NGAS(51)计算以评估新生儿生长结局。
