中文摘要：

目的足月胎儿体重与分娩方式、围产期母婴病亡率密切相关,本研究探讨利用MRI三维体积预测足月胎儿体重的可行性及准确性。资料与方法对2013年11月—2016年3月于南方医科大学南方医院行MRI及超声检查后1周内分娩的61例胎儿进行MRI三维重建并测量体积。超声预测体重采用Haldlock方程,MRI预测体重采用Baker方程,比较2种方法预测值与出生体重的误差。结果 61例孕妇完成检查并成功构建胎儿体表MRI三维模型及计算体积,其中1例胎儿运动频繁,影响体积计算,最后共纳入60例胎儿数据分析。MRI预测胎儿体重与出生体重的相关性显著（r=0.927,P〈0.05）;其随机误差略低于超声（3.4%比5.0%,P〉0.05）,平均绝对误差绝对值小于超声[（172±114）g比（227±171）g,P〈0.05];MRI相对误差≤10%的比例较超声高（95.0%比78.3%,P〈0.05）;90.0%的MRI预测值低于胎儿出生体重。结论利用胎儿MRI三维体积预测足月胎儿体重是可行的,其预测准确度高于超声,但呈低估体重趋势,可将其运用于需明确胎儿体重而超声检查受限的情况。

英文摘要：

Purpose Full-term fetal weight is closely related to the choice of delivery mode and perinatal mortality rate. Our aim is to explore the feasibility of magnetic resource image（MRI） with three-dimensional reconstruction and volume measurement in estimating fetal weight and its accuracy compared to ultrasound（US） examination. Materials and Methods Analyzed the MRI volume measurement of 61 fetuses delivered within 7 days after MRI and ultrasound examination in our hospital between November 2013 and March 2016 using MRI three-dimensional reconstruction. The fetal weight estimated by MRI was calculated by the equation developed by Baker et al and the US estimation of fetal weight was performed according to Haldlock et al, the MRI and US estimation of fetal weight were compared. Results 60 fetuses were included and qualified MRI three-dimensional reconstruction models, one was excluded because of frequent movement. The MRI estimation of fetal weight and the birth weight correlated significantly（r=0.927, P〈0.05）. The MRI estimation of fetal weight had a lower percentage of random error than US（3.4% vs 5.0%, P〉0.05）, as well as mean absolute error [（172±114） g vs（227±171） g, P〈0.05], but a higher percentage of relative error ≤ 10% than US（95.0% vs 78.3%, P〈0.05）, with an underestimation in 90.0% fetuses compared with birth-weight. Conclusion Full-term fetal weight estimation by using MRI with three-dimensional reconstruction and volume measurement is feasible and more accurate than ultrasound, but lower than the actual weight. This method can be applied in estimating fetal weight in the case of ultrasound examination limited.