Placental magnetic resonance imaging T2*measurements in normal pregnancies and in those complicated by fetal growth restriction
Placental magnetic resonance imaging T2*measurements in normal pregnancies and in those complicated by fetal growth restriction
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DOI：
10.1002/uog.14917
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发表时间：
2016-06-01
影响因子：
7.1
通讯作者：
Sorensen, A.
中科院分区：
文献类型：
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作者：
Sinding, M.;Peters, D. A.;Sorensen, A.
目的磁共振成像（MRI）可变横向弛豫时间（T2*）取决于多种因素，其中一个重要因素是脱氧血红蛋白的存在。我们的目的是描述正常妊娠和胎儿生长受限（FGR）妊娠的胎盘T2*测量。方法选取24例妊娠24-40周的正常妊娠和4例估计胎儿体重低于1百分位的FGR病例。在MRI之前，进行了超声检查，包括多普勒血流测量。T2*值采用梯度回波MRI序列计算，并在16个不同的回波时间读出。在正常妊娠中，进行重复T2*测量，并评估观察者间的可重复性，以估计该方法的可重复性。FGR患者行胎盘组织学检查。结果该方法在技术重复性和观察者间重复性方面具有稳健性。然而，由于正常胎盘的异质性，存在一些切片间的差异。因此，我们根据每个胎盘的两块切片的平均值来估计T2*。正常妊娠时，随着胎龄的增加，胎盘T2*值明显降低，妊娠24周时平均+/- SD值为120 +/- 17 ms，妊娠32周时平均+/- 16 ms，妊娠40周时平均+/- 17 ms。3例FGR患者均有多普勒血流异常、母体灌注不足的组织学征象及T2*值（Z-score）降低
Objectives The magnetic resonance imaging (MRI) variable transverse relaxation time (T2*) depends on multiple factors, one important one being the presence of deoxyhemoglobin. We aimed to describe placental T2* measurements in normal pregnancies and in those with fetal growth restriction (FGR).Methods We included 24 normal pregnancies at 24-40weeks' gestation and four FGR cases with an estimated fetal weight below the 1st centile. Prior to MRI, an ultrasound examination, including Doppler flow measurements, was performed. The T2* value was calculated using a gradient echo MRI sequence with readout at 16 different echo times. In normal pregnancies, repeat T2* measurements were performed and interobserver reproducibility was assessed in order to estimate the reproducibility of the method. Placental histological examination was performed in the FGR cases.Results The method was robust regarding the technical and interobserver reproducibility. However, some slice-to-slice variation existed owing to the heterogeneous nature of the normal placenta. We therefore based T2* estimations on the average of two slices from each placenta. In normal pregnancies, the placental T2* value decreased significantly with increasing gestational age, with mean +/- SD values of 120 +/- 17 ms at 24 weeks' gestation, 84 +/- 16 ms at 32 weeks and 47 +/- 17 ms at 40 weeks. Three FGR cases had abnormal Doppler flow, histological signs of maternal hypoperfusion and a reduced T2* value (Z-score