Volume and vascularity: Using ultrasound to unlock the secrets of the first trimester placenta

Abstract

Fetal growth restriction (FGR) is a major cause of perinatal morbidity and mortality. Identifying which pregnancies are at risk of FGR facilitates enhanced surveillance and early delivery before fetal demise can ensue. However, existing risk stratification strategies yield an unacceptably low detection rate. A robust and reliable first trimester screening test for FGR would not only enable high-risk women to be appropriately monitored but would facilitate future trials for possible interventions to enhance fetal growth. Both the volume and vascularity of the first trimester placenta has been demonstrated to be linked to adverse pregnancy outcomes including FGR and pre-eclampsia. The investigation of novel ultrasound markers for FGR are discussed along with the development of methods for fully automatic placental volume estimation which has the potential for use as part of a multivariable population-based screening test. Aim To review novel automated techniques for ultrasound measurement of placental volume and utero-placental perfusion, and to illustrate how these might have utility in the development of a screening test for fetal growth restriction. Introduction Birth weight is dependent upon numerous factors including gestational age at the time of delivery [1]; maternal characteristics [1-3]; and placental volume, vasculature and function [4]. FGR is the term used to describe babies that do not achieve their inherent growth potential, and this term is often used synonymously with 'small-forgestational-age' (SGA) although the two are distinctly different. SGA is defined as a

Characterization of Placental Microvascular Architecture by MV‐Flow Imaging in Normal and Fetal Growth–Restricted Pregnancies

“…Previously, 3-dimensional power Doppler imaging has been used to quantitatively analyze the placental microvascular architecture in unaffected and FGR fetuses; however, most of these studies were limited to early pregnancy and have not found wide clinical application. [13][14][15] Challenges may be related to equipment settings, requirements for experienced operators, and low reproducibility in the second and third trimesters. Magnetic resonance imaging (MRI) is a promising modality capable of measuring volumetric blood flow in the placenta, as it can quantify volumetric flow in the maternal and fetal sides separately.…”

“…Previously, 3‐dimensional power Doppler imaging has been used to quantitatively analyze the placental microvascular architecture in unaffected and FGR fetuses; however, most of these studies were limited to early pregnancy and have not found wide clinical application 13–15 . Challenges may be related to equipment settings, requirements for experienced operators, and low reproducibility in the second and third trimesters.…”

Hierarchical Random Walker Segmentation for Large Volumetric Biomedical Images

“…The seminal work of Grady [18] is the basis of a large number of publications with applications in biomedicine (fluorescent cell tracking [35], pap smear cells [10], tumor [40], [41], placenta [30], airway segmentation [34], [42], multimodal problems [3], [2]) and geophysical research [17]). It is also used in other algorithms (image superpixel segmentation [33] and deep learning techniques [28]).…”

Advances in imaging feto-placental vasculature: new tools to elucidate the early life origins of health and disease

“…[135][136][137] Uteroplacental vasculature can be identified towards the end of the first trimester, 138 and there have been recent striking developments in 3D ultrasonography to obtain human placental volumes and overlaying power Doppler ultrasound of the major vasculature. 139 Moreover, 3D ultrasound has been used to reveal placental volume and vascularity. [140][141][142][143][144] These approaches provide not only the opportunity for a screening test for growth restriction but also novel insight into how placental vasculature informs future health outcomes.…”