The haemodynamics of the human placenta in utero

Dellschaft, Neele; Hutchinson, George; Shah, Simon; Jones, Nia; Bradley, Christopher R.; Leach, Lopa; Platt, Craig; Bowtell, Richard; Gowland, Penny

doi:10.1101/2020.02.07.938589

Cited by 12 publications

(16 citation statements)

References 65 publications

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“…The predicted flow had an exponential distribution of velocities, typical for a random porous medium [30], with the range of ≈0-2 mm/s. This is consistent with previous MRI in vivo estimations that reported regions of slow (< 0.5 mm/s) and fast (> 1 mm/s) blood flow [31]. Furthermore, our results suggest a new hypothesis that local IVS pore sizes influence nutrient and gaseous exchange efficacy.…”

Section: Discussionsupporting

confidence: 92%

A massively multi-scale approach to characterising tissue architecture by synchrotron micro-CT applied to the human placenta

Tun

Poologasundarampillai

Bischof

et al. 2020

Preprint

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Multi-scale structural assessment of biological soft tissue is challenging but essential to gain insight into structure-function relationships of tissue/organ. Using the human placenta as an example, this study brings together sophisticated sample preparation protocols, advanced imaging, and robust, validated machine-learning segmentation techniques to provide the first massively multi-scale and multi-domain information that enables detailed morphological and functional analyses of both maternal and fetal placental domains. Finally, we quantify the scale-dependent error in morphological metrics of heterogeneous placental tissue, estimating the minimal tissue scale needed in extracting meaningful biological data. The developed protocol is beneficial for high-throughput investigation of structure-function relationships in both normal and diseased placentas, allowing us to optimise therapeutic approaches for pathological pregnancies. In addition, the methodology presented is applicable in characterisation of tissue architecture and physiological behaviours of other complex organs with similarity to the placenta, where an exchange barrier possesses circulating vascular and avascular fluid spaces.SummaryUsing the human placenta as an example, this study brings together sophisticated sample preparation protocols, advanced 3D X-ray imaging, and robust, validated machine-learning segmentation techniques to provide massively multi-scale and multi-domain insights on vascular-rich organ morphology and function.

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Section: Discussionsupporting

confidence: 92%

A massively multi-scale approach to characterising tissue architecture by synchrotron micro-CT applied to the human placenta

Tun

Poologasundarampillai

Bischof

et al. 2020

Preprint

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“…This point is highlighted in Figure 8, which shows that the departure from monoexponential decay for a given kurtosis is greater when the underlying diffusivity is higher. Other investigators have used DKI in combination with an acquisition using relatively low b ‐values to capture complex blood flow in the placenta 27 . However, as discussed above, our data suggest that the IVIM model offers better performance in normal and inflamed marrow.…”

Section: Discussionmentioning

confidence: 59%

An information‐based comparison of diffusion attenuation models in normal and inflamed bone marrow

et al. 2020

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Diffusion‐weighted imaging has received attention as a method for characterizing inflammatory exudates in bone marrow in immune‐mediated inflammatory diseases and reveals an increase in diffusivity in regions of bone marrow oedema. Various models of diffusion attenuation have been investigated but the model providing the best description of tissue pathophysiology in regions of marrow oedema is unknown. Determining the most appropriate model is an important step towards protocol optimization and the development of a robust and clinically useful method. We aimed to determine which of three candidate models of diffusion attenuation most accurately describes the acquired signal from normal and inflamed bone marrow. 11 subjects with spondyloarthritis and evidence of active inflammation (ie bone marrow oedema) on MRI and 17 patients with no evidence of active inflammation underwent diffusion‐weighted imaging of the sacroiliac joints (b‐values 0, 50, 100, 300 and 600 s/mm2). Monoexponential, intravoxel incoherent motion (IVIM) and kurtosis models were fitted to the acquired signal from regions of interest in areas of bone marrow oedema and normal marrow. The three models were compared in terms of sum of squared error and information content (corrected Akaike information criterion). Model parameters were compared between regions of bone marrow oedema and regions of normal marrow. f the three models investigated, the IVIM model provided the best description of the signal over the 0‐600 s/mm2 range across normal and inflamed bone marrow. There was a particular advantage of the IVIM model in normal marrow, where it was best able to capture the pronounced fast diffusion component observed in several cases. However, IVIM and kurtosis effects both became smaller and the signal behaviour became closer to monoexponential in the presence of bone marrow oedema. Our data suggest that increases in Dtissue (in the IVIM framework) might account for the reduced deviation from monoexponential behaviour in oedematous bone.

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“…30 More recently, Zhu et al used QSM in the placenta of nonhuman primates to measure iron content of injected ferumoxytol, 31 and Dellschaft et al applied QSM in the human placenta to demonstrate a difference in placental oxygenation between healthy pregnancies and those complicated by preeclampsia. 32 In the present study, we focused on the feasibility of performing placental QSM in relatively large number of healthy pregnancies to demonstrate that magnetic susceptibility of the placenta reflects placental oxygenation. We investigated for the first time the normative trajectories of susceptibility and R * 2 across a wide range of GA in the second half of pregnancy, their responses to induced maternal hyperoxia, and comparison of measurements between 1.5T and 3T.…”

Section: Discussionmentioning

confidence: 99%

“…In the context of fetal imaging, Neelavalli et al measured susceptibility of the superior sagittal sinus in the fetal brain for oxygenation measurement, with a long cylinder assumption in their postprocessing method 30 . More recently, Zhu et al used QSM in the placenta of nonhuman primates to measure iron content of injected ferumoxytol, 31 and Dellschaft et al applied QSM in the human placenta to demonstrate a difference in placental oxygenation between healthy pregnancies and those complicated by preeclampsia 32 . In the present study, we focused on the feasibility of performing placental QSM in relatively large number of healthy pregnancies to demonstrate that magnetic susceptibility of the placenta reflects placental oxygenation.…”

Section: Discussionmentioning

confidence: 99%

Feasibility of QSM in the human placenta

Zun

Kapse

Quistorff

et al. 2020

Magnetic Resonance in Med

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Purpose: Quantitative susceptibility mapping (QSM) is an emerging tool for the precise characterization of human tissue, including regional oxygenation. A critical function of the human placenta is oxygen transfer to the developing fetus, which remains difficult to study in utero. The purpose of this study is to investigate the feasibility of performing QSM in the human placenta in utero. Methods: In healthy pregnant women, 3D gradient echo data of the placenta were acquired with prospective respiratory gating at 1.5 Tesla and 3 Tesla. A brief period (6-7 min) of maternal hyperoxia was induced to increase placental oxygenation in a subset of women scanned at 3 Tesla, and data were acquired before and during oxygen administration. Susceptibility and T * 2 /R * 2 maps were reconstructed from gradient echo data, and mean and SD of these measures within the whole placenta were calculated. Results: A total of 54 women were studied at a mean gestational age of 30.7 ± 4.2 (range: 24 5/7-38 4/7) weeks. Susceptibility and T * 2 maps demonstrated lobular contrast reflecting regional oxygenation difference at both field strengths. SD of susceptibilities, mean R * 2 , and SD of R * 2 of the placenta showed a linear relationship with gestational age (P < .01 for all). These measures were also responsive to maternal hyperoxia, and there was an increasing response with advancing gestational age (P < .01 for all). Conclusion: This study demonstrates the feasibility of performing placental QSM in pregnant women and supports the potential for placental QSM to provide noninvasive in vivo assessment of placental oxygenation.

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The haemodynamics of the human placenta in utero

Cited by 12 publications

References 65 publications

A massively multi-scale approach to characterising tissue architecture by synchrotron micro-CT applied to the human placenta

A massively multi-scale approach to characterising tissue architecture by synchrotron micro-CT applied to the human placenta

An information‐based comparison of diffusion attenuation models in normal and inflamed bone marrow

Feasibility of QSM in the human placenta

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