Fetal vascular ultrasound assessment to identify growth restriction and reduce stillbirth

博士项目的目的：开发一种方法，这将使胎儿主动脉弹性属性计算从超声扫描;开发新的超声协议和信号和图像处理技术，为目前的临床成像系统和国家的最先进的超声成像;调查是否主动脉弹性测量这种方法区分生长受限从正常胎儿。项目描述：有超过3,000死产每年在英国，其中许多与胎儿生长受限（FGR）。死产约占每200例妊娠中的1例，是围产期死亡的主要原因。2016年，《柳叶刀》的“结束可预防的死产系列”表明，英格兰和威尔士的死产率是西欧最高的，并且在过去20年中变化不大。1，2英国最近的一项研究发现FGR（定义为定制的出生体重低于第10百分位数）是死产率的最大单一因素，造成大约43%的死产。3减少死产的最有希望的方法之一是早期诊断FGR。研究表明，胎儿生长迟缓的高死亡率主要是由于缺乏对这种疾病的认识，而不是没有能力对其进行管理。4预防战略主要侧重于改变社会经济参数，如改善获得护理的机会，或改善孕妇怀孕前的福祉，如降低孕妇肥胖率。1然而，这些战略难以在移动的人口中实施，当今西方社会中年龄更大、更肥胖的孕妇群体。妊娠期FGR的主要筛查工具是胎儿超声（US）扫描，可用于测量胎儿的生物统计学（尺寸），从中可以估计胎儿体重，以及胎儿血流，从中可以评估胎儿对缺氧的适应性。然而，尽管有这些测量，检测FGR的灵敏度仍然<40%。与传统的胎儿生物统计学和血流多普勒检查相比，需要一种更敏感的超声标记物来识别第三组胎儿，胎儿血管系统的评估正在成为一个新的研究领域，有可能提供胎儿对母体刺激的心血管适应性的信息，比子宫动脉、大脑中动脉和脐动脉的血流多普勒检查更早地检测到。现在可以使用先进的基于US的技术评估胎儿主动脉特性，这可能在FGR筛查中具有实用性。数据表明，生长受限胎儿的主动脉僵硬度增加，6，7然而，迄今为止，还没有方法可用于临床实践，以评估血管弹性在pregnancy.In这项研究中，我们的目标是开发先进的US和脉搏波分析技术，以估计胎儿血管特性。这将包括研究原始射频（RF）US数据的使用，以及最先进的超快US成像8，在整个视场中提供更高的时间分辨率。我们将评估这些新技术测量的主动脉弹性是否能区分生长受限胎儿和正常胎儿。如果我们的开发成功，这将提供一种新的方法来提高FGR的检测和降低死胎率。我们希望通过与佳能医疗系统的合作，该方法可以在美国扫描仪中实施。

Aim of the PhD Project:Develop a methodology which will enable fetal aortic elastic properties to be calculated from an ultrasound scan;Develop new ultrasound protocols and signal and image processing techniques for both current clinical imaging systems and state-of-the-art ultrasound imaging;Investigate whether aortic elasticity measured by this methodology differentiates growth-restricted from normal fetuses.Project description:There are over 3,000 stillbirths per year in the UK, many of which are associated with fetal growth restriction (FGR). Stillbirth affects about 1 in 200 pregnancies and is the leading cause of perinatal death. In 2016, the Lancet's "Ending Preventable Stillbirth Series" indicated that stillbirth rates in England and Wales are the highest in Western Europe and have changed little in the past 20 years.1,2 A recent UK study identified FGR, defined as a customised birthweight below the 10th percentile, as the single largest contributor to stillbirth rates, being responsible for about 43% of stillbirths.3One of the most promising approaches to reduce stillbirths is early diagnosis of FGR. It has been shown that the high mortality rates of FGR are mainly due to lack of recognition of the condition rather than inability to manage it.4 Preventive strategies mostly focus on altering socio-economic parameters, such as improved access to care, or improving maternal wellbeing prior to pregnancy, such as reduced maternal obesity rates.1 However, these strategies are difficult to implement in the mobile, older and more obese pregnant populations of current Western societies. Therefore, a method to accurately screen for FGR to diagnose it early is required.The main screening tool for FGR during pregnancy is fetal ultrasound (US) scanning, which can be used to measure fetal biometry (dimensions) from which fetal weight can be estimated, and fetal blood flow from which fetal adaptation to hypoxia can be assessed. However, despite these measurements, the sensitivity in detecting FGR remains <40%.5 Therefore, a more sensitive ultrasonographic marker is needed - compared to the traditional fetal biometry and blood flow Doppler examination - to identify those fetuses in the third-trimester scan who are at risk of FGR in the next few weeks.Assessment of fetal vasculature is emerging as a novel area of research with potential to provide information about fetal cardiovascular adaptations in response to maternal stimuli at a much earlier stage than can be detected by blood flow Doppler examinations in the uterine, middle cerebral, and umbilical arteries. It is now possible to assess fetal aortic properties using advanced US-based techniques, which may have utility in FGR screening. Data suggest that growth restricted fetuses have increased aortic stiffness,6,7 however to date there is no methodology which can be used in clinical practice to assess vascular elasticity during pregnancy.In this study, we aim to develop advanced US and pulse wave analysis techniques to estimate fetal vascular properties. This will include investigating the use of raw radio-frequency (RF) US data, as well as state-of-the-art ultrafast US imaging8, providing higher temporal resolution across the full field-of-view. We will assess whether aortic elasticity measured by these new techniques differentiates growth-restricted from normal fetuses. If our development is successful, this will provide a novel way to improve detection of FGR and reduce stillbirth rates. It is hoped that the methodology could be implemented in US scanners through our collaboration with Canon Medical Systems.