New Frontiers in Placenta Tissue Imaging

Abstract

The placenta is a highly vascularized organ with unique structural and metabolic complexities. As the primary conduit of fetal support, the placenta mediates transport of oxygen, nutrients, and waste between maternal and fetal blood. Thus, normal placenta anatomy and physiology is absolutely required for maintenance of maternal and fetal health during pregnancy. Moreover, impaired placental health can negatively impact offspring growth trajectories as well as increase the risk of maternal cardiovascular disease later in life. Despite these crucial roles for the placenta, placental disorders, such as preeclampsia, intrauterine growth restriction (IUGR), and preterm birth, remain incompletely understood. Effective noninvasive imaging and image analysis are needed to advance the obstetrician's clinical reasoning toolkit and improve the utility of the placenta in interpreting maternal and fetal health trajectories. Current paradigms in placental imaging and image analysis aim to improve the traditional imaging techniques that may be time-consuming, costly, or invasive. In concert with conventional clinical approaches such as ultrasound (US), advanced imaging modalities can provide insightful information on the structure of placental tissues. Herein we discuss such imaging modalities, their specific applications in structural, vascular, and metabolic analysis of placental health, and emerging frontiers in image analysis research in both preclinical and clinical contexts.

Figure 1:

Examples of imaging modalities that can be used to generate insight into anatomical structure, vascular, and metabolic function of the placenta.^,,,,

Figure 2:

Schematic representation of spatial resolution versus penetration depth of various preclinical (dashed border) and clinical (solid border) imaging modalities used for placental and extraembryonic tissue imaging. The temporal resolution is represented by a pseudo-colormap with red representing slow and violet representing fast. The cost is represented by a different pseudo-colormap with gray representing low-cost and black representing high-cost. Note that PAI has a dashed white border which represents its primary use in preclinical studies but has yet to be clinically used in any form. Given the absence of clinical applications for PAI, associated costs for this technique are not included.