On the use of multicompartment models of diffusion and relaxation for placental imaging

Placental MRI Predicts Fetal Oxygenation and Growth Rates in Sheep and Human Pregnancy

“…When choosing a model, the user must trade‐off between acquisition simplicity and interpretability depending on the application. [ 57 ] Here, we made use of DECIDE, a new technique for separating fetal and maternal circulations with an approach that is relatively rapid without the need for gating, and our MRI‐derived feto‐placental oxygenation results are consistent with what is known about oxygen distribution in the fetus. [ 9 ] Nonetheless, the model makes several assumptions.…”

Assessing within‐subject rates of change of placental MRI diffusion metrics in normal pregnancy

“…Using descriptives measures of the histograms of all $$$ {\mathrm{T}}_2^{\ast } $$$ and ADC values for every placental voxel allows the capture of subtle changes in the distribution of these imaging metrics, which can then be interpreted as being representative of both smaller‐scale and regional differences in the biological properties of the underlying placental tissues. Recent related work takes advantage of these approaches, including whole placenta histogram analysis 4,46 or looking at more focused regions of interest 19 . Histograms depicting whole‐placenta $$$ {\mathrm{T}}_2^{\ast } $$$ and ADC voxel values could be useful for visualizing the change in $$$ {\mathrm{T}}_2^{\ast } $$$ and ADC signal, with the change in shape of these histograms reflecting the change in placental tissue heterogeneity that occurs as the placenta develops.…”

“…However, the complex interactions between structural and functional properties at the core of placental function is influenced by both the microstructure of the villous trees and the properties of the intervillous space, and therefore calls for more comprehensive assessments. Individual contrasts fall short of reflecting this, and combined dMRI scans have therefore recently gained interest, assessing oxygenation and microstructure simultaneously and providing a larger sampled parameter space for more advanced analysis techniques 1,19,20 …”

“…Individual contrasts fall short of reflecting this, and combined dMRI scans have therefore recently gained interest, assessing oxygenation and microstructure simultaneously and providing a larger sampled parameter space for more advanced analysis techniques. 1,19,20 Secondly, the majority of previous studies are cross-sectional, reporting how MRI measures of placental function or microstructure change throughout pregnancy in different subjects imaged at different times. Resulting "normal" curves illustrating the behavior of placental properties over gestation therefore fail to inform about the extent of normal within-subject variability, making it difficult to investigate the robustness of such measures.…”

The effect of maternal position on placental blood flow and fetoplacental oxygenation in late gestation fetal growth restriction: a magnetic resonance imaging study

“…Separating maternal and fetal circulations within the placenta is important as they may independently contribute to, or be affected by, the pathophysiology of FGR (Ghidini, 1996; Kingdom et al., 2000). MRI techniques that enable the measurement of blood flow and oxygen saturation within each compartment (maternal blood, fetal blood and villous tissue) may aid our understanding of the functional differences between placentae of healthy and complicated pregnancies (Clark et al., 2022; James et al., 2017; Melbourne, 2021; Slator et al., 2019). Diffusion‐relaxation Combined Imaging for Detailed Placental Evaluation (DECIDE) is a placenta‐specific three‐compartment model combining T2 relaxation and the Intravoxel Incoherent Motion model of diffusion weighted imaging (DWI‐IVIM) to separate the maternal blood, fetal blood and cellular tissue components of the placental MR signal.…”