Lee Wesley, Deter Russell L, McNie Beverley, Gonçalves Luis F, Espinoza Jimmy, Chaiworapongsa Tinnakorn, Balasubramaniam Mamtha, Romero Roberto
Division of Fetal Imaging, Department of Obstetrics and Gynecology, William Beaumont Hospital, Royal Oak, MI 48073-6769, USA.
J Ultrasound Med. 2005 Jun;24(6):817-28.
The goals were to introduce fractional arm volume (AVol) as a new soft tissue parameter of fetal growth assessment and to develop individualized growth standards, based on Rossavik models, for AVol, midarm circumference (ArmC), and humeral diaphysis length (HDL).
A prospective longitudinal study of 22 fetuses was conducted using 2- and 3-dimensional sonography. Three new growth parameters (HDL, ArmC, and AVol) were used to establish individualized standards for arm growth with the use of Rossavik functions [P=c(t)k (+) s(t), where P is the anatomic parameter; c, k, and s are model coefficients; and t is the time variable]. Second-trimester models were specified from the linear slopes of growth curves before approximately 28.0 menstrual weeks. For a given fetus, normal third-trimester trajectories were predicted for each parameter. Observed and predicted measurements were compared by percent deviations.
Rossavik functions fit all parameter trajectories extremely well (R(2)=95.7%-99.4%). By fixing coefficients k at their mean values, their respective fits did not change, and the variabilities of both coefficients c and s were reduced. Coefficient c was also significantly related to second-trimester slope, as was s to c, for all 3 parameters (R(2)=97.7%-98.7%; P<.0001). Mean percent deviations between observed and predicted third-trimester HDL, ArmC, and AVol measurements were -0.1% +/- 2.9%, 0.5% +/- 4.6%, and 0.4% +/- 8.5%, respectively.
Individualized growth assessment, using HDL and ArmC, can accurately predict normal arm growth during the third trimester of pregnancy. AVol may also allow earlier detection and improved monitoring of soft tissue abnormalities that can occur in fetuses with growth disturbances.
引入上肢部分体积（AVol）作为评估胎儿生长的新软组织参数，并基于罗萨维克模型制定AVol、上臂围（ArmC）和肱骨干长度（HDL）的个体化生长标准。
采用二维和三维超声对22例胎儿进行前瞻性纵向研究。使用三个新的生长参数（HDL、ArmC和AVol），通过罗萨维克函数[P = c(t)k(+)s(t)，其中P为解剖参数；c、k和s为模型系数；t为时间变量]建立上肢生长的个体化标准。孕中期模型根据约28.0孕周前生长曲线的线性斜率确定。对于给定胎儿，预测每个参数在孕晚期的正常轨迹。通过百分比偏差比较观察值和预测值。
罗萨维克函数能很好地拟合所有参数轨迹（R² = 95.7% - 99.4%）。将系数k固定为其平均值时，各自的拟合度不变，系数c和s的变异性均降低。对于所有三个参数，系数c也与孕中期斜率显著相关，s与c也显著相关（R² = 97.7% - 98.7%；P <.0001）。观察值与预测值在孕晚期HDL、ArmC和AVol测量中的平均百分比偏差分别为 -0.1% ± 2.9%、0.5% ± 4.6%和0.4% ± 8.5%。
使用HDL和ArmC进行个体化生长评估能够准确预测妊娠晚期的正常上肢生长。AVol还可能有助于更早发现并更好地监测生长受限胎儿可能出现的软组织异常。
