正常中晚孕期胎盘磁共振影像的初步研究

MRI of Normal Placenta in Second and Third Trimester

【目的】探讨磁共振(MRI)对正常中晚孕期胎盘成熟度的诊断分级及其与胎龄的关系。【方法】收集中山大学附属第一医院2003年11月至2006年7月间行MRI检查的69例孕妇中B超检查未提示胎盘病变者56例。根据T2WI显示的胎盘三层结构即绒毛膜板变化、胎盘实质信号、基底膜形态等,将其成熟度分为Ⅰ、Ⅱ、Ⅲ三等级,并分析胎盘成熟度及其与胎龄的关系。【结果】胎盘的三层结构在T2WI上显示较好。56例不同胎龄组与胎盘成熟度分级的MRI分级为:孕24～27周胎盘全部属于Ⅰ级(7例);孕28～31周85.0%属于Ⅰ级(17/20例),15.0%为Ⅱ级(3/20例);32～35周成熟度Ⅱ级占50.0%(9/18例);36周以后大部分为Ⅱ级,占81.8%(9/11例),亦可见到更高成熟度者。【结论】MRI不仅可以对正常胎盘成熟度做出分级,而且对其胎盘成熟度及其与胎龄的关系有较好的相关性。

[Objective ] To provide the MRI appearance of the normal placenta in the second and third pregnancy trimester and summarize the relation between placental maturity and gestation age. [Methods] From November 2003 to July 2006, 56 singleton pregnancies were investigated by MRI. Their mean age was 28.2 years （range 18 - 35 years）, the average gestation age was 31.9 weeks （range 24 - 40 weeks）. Depending on three layers of placenta demonstrated by T2WI, placental maturity were assessed and divided into 3 grading. [Results]Three layers of placenta in MRI can be shown best on T2WI.The MRI grading of normal placental maturity in 56 cases was： between the 24 th to the 27 th gestation age （GA）, 7belonged to grading Ⅰ ; between 28 - 31GA, 17was grading Ⅰ （85.0%）, 3 was grading Ⅱ（15.0%） ; between 32-35 GA, 9 was grading Ⅱ （50.0%） ; after 36 GA, 9 was grading Ⅱ （81.8%）, 2 was grading Ⅲ （18.2%）. [ Conclusions ] MRI can not only differentiate the placenta maturity grading, but also can have a good correlation between placental maturity and gestation age.