In Vivo Quantification of Placental Insufficiency by BOLD MRI: A Human Study

Abstract

Fetal health is critically dependent on placental function, especially placental transport of oxygen from mother to fetus. When fetal growth is compromised, placental insufficiency must be distinguished from modest genetic growth potential. If placental insufficiency is present, the physician must trade off the risk of prolonged fetal exposure to placental insufficiency against the risks of preterm delivery. Current ultrasound methods to evaluate the placenta are indirect and insensitive. We propose to use Blood-Oxygenation-Level-Dependent (BOLD) MRI with maternal hyperoxia to quantitatively assess mismatch in placental function in seven monozygotic twin pairs naturally matched for genetic growth potential. In-utero BOLD MRI time series were acquired at 29 to 34 weeks gestational age. Maps of oxygen Time-To-Plateau (TTP) were obtained in the placentas by voxel-wise fitting of the time series. Fetal brain and liver volumes were measured based on structural MR images. After delivery, birth weights were obtained and placental pathological evaluations were performed. Mean placental TTP negatively correlated with fetal liver and brain volumes at the time of MRI as well as with birth weights. Mean placental TTP positively correlated with placental pathology. This study demonstrates the potential of BOLD MRI with maternal hyperoxia to quantify regional placental function in vivo.

T2*‐weighted placental MRI: basic research tool or emerging clinical test for placental dysfunction?

“…In addition, three animal studies described changes in placental signal intensity during maternal hypoxia, normoxic hypercapnia and injection of a vasoconstrictor. Human studies were performed at both 1.5 T and 3 T using single‐shot GE‐EPI sequences. However, the specific echo‐time (TE) and repetition time (TR) varied between studies (Table S1).…”

“…Hyperoxic BOLD effect (ΔBOLD) in human pregnancies complicated by fetal growth restriction (FGR) . Three studies included FGR pregnancies, with FGR defined by low birth weight or low birth weight in combination with abnormal postnatal placental examination (Table S1). Initially, a small study including four FGR cases demonstrated inconsistent results regarding the hyperoxic BOLD effect.…”

Improved fetal blood oxygenation and placental estimated measurements of diffusion‐weighted MRI using data‐driven Bayesian modeling

“…Since the oxygen extraction by the fetus will always be greater than zero, a concentration gradient is always necessary, depending on the blood delivery conditions and blood velocity through the intervillous space. Deeper in the intervillous space the of blood will be somewhere between arterial and venous saturation level as suggested by ‐weighted images of the placenta . Assuming that fetal oxygen extraction changes with gestational age, variations in the gradient of maternal blood saturation may influence our estimates of fetal blood saturation.…”

Linear convolution model of fetal circulation for hemodynamic responses to maternal hyperoxia using in utero functional MRI

“…While this study focused on analyzing the temporal changes of blood oxygenation during maternal hyperoxia, Luo et al analyzed the spatiotemporal pattern of BOLD responses of the placenta to maternal hyperoxia, and found that the oxygen time-to-plateau of BOLD time course is significantly correlated with fetal brain volume and placental pathology [2]. The hemodynamic response was modeled as the convolution of a gamma function with the given oxygen paradigm.…”