Assessment of placental perfusion and oxygenation using novel MRI approaches.

在妊娠早期，滋养层细胞迁移到螺旋动脉的管腔导致5-10折叠末端 动脉扩张，从而增加通过胎盘的血流量。胎盘功能不全与 螺旋动脉的这种转换失败，并导致最常见的妊娠并发症 如胎儿生长受限(FGR)和子痫前期(PE)。在管理和治疗中 妊娠合并胎盘功能不全，早期可靠的检测至关重要，因为到了那个时候 胎盘功能障碍明显，对胎儿或母亲的病理改变是不可逆转的。 已经提出了许多方法来识别子宫内胎盘功能不全。尤其是，有 人们提出了各种基于MRI的方法来测量胎盘功能。然而，所有先前的研究都部署了 没有对胎盘进行重大优化的标准脑MRI成像方案或使用的方法 对胎盘异常不是很敏感。在过去的几年里，我们已经推出了先进的专用核磁共振 速度选择性动脉自旋标记胎盘特异性血流灌注和氧合测量技术 (VSASL)和定量易感图谱(QSM)，并在我们的 初步数据。在这项研究中，我们将首先优化胎盘VSASL在3T，以提高信噪比和 图像质量(目标1)。然后，我们将应用我们的胎盘VSASL和QSM方法诊断为妊娠 用FGR或PE和健康孕妇来确定胎盘血流和氧合的差异 FGR/PE和对照(目标2)。最后，我们将通过比较活体胎盘来验证我们的磁共振成像方法 针对胎盘病理和临床结果的措施(目标3)。这个项目的成功完成将 确定胎盘功能不全与体内胎盘灌注/氧合改变之间的关系 测量。最终，这将开发出胎盘健康和疾病的早期和可靠的生物标记物，并将 协助开发和评估旨在改善妊娠结局的新干预方法。

Early in pregnancy migration of trophoblast cells to the lumen of the spiral arteries leads to 5-10 fold terminal dilation of the arteries, thereby increasing blood flow through the placenta. Placental insufficiency is associated with failure of this conversion of the spiral arteries, and results in the most common complications of pregnancy such as fetal growth restriction (FGR) and preeclampsia (PE). In the management and treatment of pregnancies complicated by placental insufficiency, early and reliable detection is critical, because by the time placental dysfunction becomes evident, the pathological changes to the fetus or mother are irreversible. Numerous approaches have been suggested for identifying placental insufficiency in utero. Particularly, there have been various MRI-based methods proposed to measure placental function. However, all of prior studies deployed standard imaging schemes of brain MRI without significant optimization for the placenta or used the methods that are not very sensitive to placental abnormalities. Over the past several years, we have advanced dedicated MRI techniques for placental-specific perfusion and oxygenation measures using velocity-selective arterial spin labeling (VSASL) and quantitative susceptibility mapping (QSM), and have demonstrated promising results in our preliminary data. In this study, we will first optimize placental VSASL at 3 T for improved signal-to-noise ratio and image quality (aim 1). We will then apply our approaches of placental VSASL and QSM in pregnancies diagnosed with FGR or PE and healthy pregnancies to determine differences in placental perfusion and oxygenation between FGR/PE and controls (aim 2). Lastly, we will validate our MR imaging methods by comparing in-vivo placental measures against placental pathology and clinical outcomes (aim 3). Successful completion of this project will determine the association between placental insufficiency and altered in-vivo placental perfusion/oxygenation measurements. Ultimately, this will develop early and reliable biomarkers of placental health and disease, and will assist in developing and assessing new interventional approaches aimed to improve pregnancy outcomes.