Characterizing the Relationship between Uterine Activity and Placental Function Across Pregnancy with MRI

项目总结/摘要 胎盘是一个重要的胎儿器官，它的作用是吸收、滋养和清除胎儿血液中的废物， 子宫。稳健的母体灌注对于该功能是必不可少的，并且需要高电容、缓慢的血液流动以 胎盘母体-胎盘灌注可因子宫收缩而暂时受损， 发生在整个怀孕期间，也称为布拉克斯顿希克斯收缩。健康胎儿，正常 发达的胎盘有足够的胎盘储备能力，布拉克斯顿希克斯收缩和轻微 血管病理学不显著影响必要的胎盘氧运输。然而，在功能失调的 储备能力差的胎盘（如一些与宫内生长受限相关的胎盘）， 事件可能导致缺氧应激。缺乏关于影响的信息和量化数据， 人类妊娠中产前子宫活动（布拉克斯顿希克斯收缩）以及这些发现是否可能 有助于表征胎盘储备和功能，并为未来检测的发展提供信息，以在 胎盘功能障碍介导的分娩期间不良结局的风险。新的评估方法 人类子宫胎盘功能和收缩对胎儿呼吸交换的影响 需要正常生长和IUGR胎儿的妊娠。在这里，我们将描述 整个妊娠期的布拉克斯顿-希克斯收缩，分析妊娠期间胎盘氧合的时空变化 并监测这些胎盘氧合变化对胎动和器官的影响 通过MRI进行氧合。我们的假设是，在布拉克斯顿希克斯收缩期间胎盘血流的变化 与正常生长的胎儿相比，IUGR胎儿可能对胎盘氧转运有更大的影响。 如果成功的话，我们将确定胎盘和胎儿在宫缩期间的MR信号变化是可能的。 了解个体胎盘储备的方法。这样的理解可以使小说的发展 治疗和监测这些动态变化的能力对于评估 新疗法为此，我们提出了以下具体目标：目标1：刻画布拉克斯顿希克斯 宫缩和胎盘氧合的相关变化 正常生长和IUGR胎儿。我们将使用T2* 标测方法表征胎盘氧合 并分析胎盘T2* 的区域差异。然后，我们将比较和关联的差异， 正常生长和IUGR胎儿的妊娠。目的2：确定胎盘氧合的影响 妊娠期布拉克斯顿-希克斯收缩对胎儿运动及脑和肝氧合的影响 正常生长和IUGR胎儿。我们将跟踪胎儿的运动，并描述胎儿的大脑和肝脏 氧合使用T2* 映射。然后，我们将比较和关联的差异，在怀孕与正常 生长和IUGR胎儿。

PROJECT SUMMARY / ABSTRACT The placenta is a vital fetal organ that serves to oxygenate, nourish, and remove waste from fetal blood in utero. Robust maternal perfusion is essential for this function and requires high capacitance, slow blood flow to the placenta. Maternal-placental perfusion can be temporarily compromised by uterine contractions, which occur throughout pregnancy, also known as Braxton Hicks contractions. Healthy fetuses with normally developed placentas have enough placental reserve capacity that Braxton Hicks contractions and minor vascular pathology do not significantly affect necessary placental oxygen transport. However, in dysfunctional placentas with poor reserve (as in some placentas associated with intrauterine growth restriction-IUGR) these events may lead to hypoxic stress. There is a lack of information and quantitative data regarding the effect of antepartum uterine activity (Braxton Hicks contractions) in human pregnancies and whether these findings may help to characterize placental reserve and function and inform development of future tests to identify fetuses at risk for adverse outcomes during delivery mediated by placental dysfunction. New methods to assess uteroplacental function in humans and the impact of contractions on fetal respiratory exchange across pregnancy in pregnancies with normally growing and IUGR fetuses are needed. Here, we will characterize Braxton Hicks contractions across gestation, analyze spatiotemporal changes in placental oxygenation during these contractions and monitor the effect of these placental oxygenation changes on fetal movement and organ oxygenation via MRI. Our hypothesis is that the change in placental flow during Braxton Hicks contractions may have a larger impact on placental oxygen transport for IUGR fetuses compared to normally growing ones. If successful we will have identified placental and fetal MR signal changes during contractions as a possible method to understand individual placental reserve. Such understanding may enable the development of novel therapies and the ability to monitor changes in these dynamics is critical to the assessment of the impact of novel therapies. Towards this end, we propose the following specific aims: Aim 1: Characterize Braxton Hicks contractions and the associated change in placental oxygenation across gestation in pregnancies with normally growing and IUGR fetuses. We will characterize placental oxygenation using T2* mapping approach and analyze regional differences in placental T2*. Then we will compare and correlate differences in pregnancies with normally growing and IUGR fetuses. Aim 2: Determine the impact of placental oxygenation change during Braxton Hicks contractions on fetal motion and brain and liver oxygenation in pregnancies with normally growing and IUGR fetuses. We will track fetal motion and characterize fetal brain and liver oxygenation using T2* mapping. Then we will compare and correlate differences in pregnancies with normally growing and IUGR fetuses.