Christopher Macgowan

Acute resveratrol exposure does not impact hemodynamics of the fetal sheep

Publisher: Wiley

Date: 06-2023

DOI: 10.14814/PHY2.15749

Abstract: Babies born growth restricted are at an increased risk of both poor short‐and long‐term outcomes. Current interventions to improve fetal growth are ineffective and do not lower the lifetime risk of poor health status. Maternal resveratrol (RSV) treatment increases uterine artery blood flow, fetal oxygenation, and fetal weight. However, studies suggest that diets high in polyphenols such as RSV may impair fetal hemodynamics. We aimed to characterize the effect of RSV on fetal hemodynamics to further assess its safety as an intervention strategy. Pregnant ewes underwent magnetic resonance imaging (MRI) scans to measure blood flow and oxygenation within the fetal circulation using phase contrast‐MRI and T 2 oximetry. Blood flow and oxygenation measures were performed in a basal state and then repeated while the fetus was exposed to RSV. Fetal blood pressure and heart rate were not different between states. RSV did not impact fetal oxygen delivery (DO 2 ) or consumption (VO 2 ). Blood flow and oxygen delivery throughout the major vessels of the fetal circulation were not different between basal and RSV states. As such, acute exposure of the fetus to RSV does not directly impact fetal hemodynamics. This strengthens the rationale for the use of RSV as an intervention strategy against fetal growth restriction.

Chatter detection based on wavelet coherence functions in micro-end-milling processes

Publisher: SAGE Publications

Date: 21-10-2018

DOI: 10.1177/0954405418808214

MRI Characterization of blood flow and oxygen delivery in the fetal sheep whilst exposed to sildenafil citrate

Publisher: S. Karger AG

Date: 2022

DOI: 10.1159/000526972

Abstract: b i Introduction: /i /b Newborns exposed to sildenafil citrate (SC) in utero have increased rates of persistent pulmonary hypertension. The mechanism behind this has not yet been fully elucidated. We aimed to utilize a combination of clinically relevant MRI techniques to comprehensively characterize the haemodynamics of the fetal sheep whilst under the influence of SC. We hypothesized that these MRI techniques would detect SC-induced increases in pulmonary blood flow and oxygen delivery prior to birth. b i Methods: /i /b At 116–117 days gestational age (term, 150 days), pregnant Merino ewes ( i n /i = 9) underwent fetal catheterization surgery. MRI scans were performed during a basal state and then repeated during a constant umbilical vein infusion of SC to measure blood flow and oxygenation within the major vessels of the fetal circulation using phase-contrast-MRI and T sub /sub oximetry. b i Results: /i /b Right and left ventricular cardiac outputs were not different between states. Pulmonary blood flow increased during the SC state resulting in elevated pulmonary oxygen delivery. Right to left heart shunting through the foramen ovale was reduced without reducing cerebral oxygen delivery. b i Conclusion: /i /b SC induces alterations to pulmonary haemodynamics i in utero /i a characteristic that if maintained may underlie or act as a precursor towards the elevated rates of poor pulmonary outcomes after birth. These MRI techniques are the first to comprehensively characterize sildenafil’s direct impact on the pulmonary vasculature and its indirect detriment to the flow of oxygen-rich blood through the foramen ovale.

Isotopic shifts in the Cenozoic Andean arc of central Chile: Records of an evolving basement throughout cordilleran arc mountain building

Publisher: Geological Society of America

Date: 08-2013

DOI: 10.1130/G34178.1

Technique for comprehensive fetal hepatic blood flow assessment in sheep using 4D flow MRI

Publisher: Wiley

Date: 07-2020

DOI: 10.1113/JP279631

Feasibility of detecting myocardial infarction in the sheep fetus using late gadolinium enhancement CMR imaging

Publisher: Springer Science and Business Media LLC

Date: 13-09-2017

DOI: 10.1186/S12968-017-0383-1

Peripheral cord insertion is associated with adverse pregnancy outcome only when accompanied by clinically significant placental pathology

Publisher: Wiley

Date: 31-07-2023

DOI: 10.1002/UOG.26206

Abstract: To examine the relationship between umbilical cord insertion site, placental pathology and adverse pregnancy outcome in a cohort of normal and complicated pregnancies. Sonographic measurement of the cord insertion and detailed placental pathology were performed in 309 participants. Associations between cord insertion site, placental pathology and adverse pregnancy outcome (pre‐ecl sia, preterm birth, small‐for‐gestational age) were examined. A total of 93 (30%) participants were identified by pathological examination to have a peripheral cord insertion site. Only 41 of the 93 (44%) peripheral cords were detected by prenatal ultrasound. Peripherally inserted cords were associated significantly ( P 0.0001) with diagnostic placental pathology (most commonly with maternal vascular malperfusion (MVM)) of which 85% had an adverse pregnancy outcome. In cases of isolated peripheral cords, without placental pathology, the incidence of adverse outcome was not statistically different when compared to those with central cord insertion and no placental pathology (31% vs 18% P = 0.3). A peripheral cord with an abnormal umbilical artery (UA) pulsatility index (PI) corresponded to an adverse outcome in 96% of cases compared to 29% when the UA‐PI was normal. This study demonstrates that peripheral cord insertion is often part of the spectrum of findings of MVM disease and is associated with adverse pregnancy outcome. However, adverse outcome was uncommon when there was an isolated peripheral cord insertion and no placental pathology. Therefore, additional sonographic and biochemical features of MVM should be sought when a peripheral cord is observed. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of maternal late gestation undernutrition on surfactant maturation, pulmonary blood flow and oxygen delivery measured by magnetic resonance imaging in the sheep fetus

Publisher: Wiley

Date: 22-09-2021

DOI: 10.1113/JP281292

Abstract: Restriction of fetal substrate supply has an adverse effect on surfactant maturation in the lung and thus affects the transition from in utero placental oxygenation to pulmonary ventilation ex utero . The effects on surfactant maturation are mediated by alteration in mechanisms regulating surfactant protein and phospholipid synthesis. This study aimed to determine the effects of late gestation maternal undernutrition (LGUN) and LGUN plus fetal glucose infusion (LGUN+G) compared to Control on surfactant maturation and lung development, and the relationship with pulmonary blood flow and oxygen delivery ( ) measured by magnetic resonance imaging (MRI) with molecules that regulate lung development. LGUN from 115 to 140 days’ gestation significantly decreased fetal body weight, which was normalized by glucose infusion. LGUN and LGUN+G resulted in decreased fetal plasma glucose concentration, with no change in fetal arterial compared to control. There was no effect of LGUN and LGUN+G on the mRNA expression of surfactant proteins ( SFTP ) and genes regulating surfactant maturation in the fetal lung. However, blood flow in the main pulmonary artery was significantly increased in LGUN, despite no change in blood flow in the left or right pulmonary artery and to the fetal lung. There was a negative relationship between left pulmonary artery flow and to the left lung with SFTP‐B and GLUT1 mRNA expression, while their relationship with VEGFR2 was positive. These results suggest that increased pulmonary blood flow measured by MRI may have an adverse effect on surfactant maturation during fetal lung development. image Maternal undernutrition during gestation alters fetal lung development by impacting surfactant maturation. However, the direction of change remains controversial. We examined the effects of maternal late gestation maternal undernutrition (LGUN) on maternal and fetal outcomes, signalling pathways involved in fetal lung development, pulmonary haemodynamics and oxygen delivery in sheep using a combination of molecular and magnetic resonance imaging (MRI) techniques. LGUN decreased fetal plasma glucose concentration without affecting arterial . Surfactant maturation was not affected however, main pulmonary artery blood flow was significantly increased in the LGUN fetuses. This is the first study to explore the relationship between in utero MRI measures of pulmonary haemodynamics and lung development. Across all treatment groups, left pulmonary artery blood flow and oxygen delivery were negatively correlated with surfactant protein B mRNA and protein expression in late gestation.

Differential gene responses 3 days following infarction in the fetal and adolescent sheep heart

Publisher: American Physiological Society

Date: 03-2020

DOI: 10.1152/PHYSIOLGENOMICS.00092.2019

Abstract: There are critical molecular mechanisms that can be activated to induce myocardial repair, and in humans this is most efficient during fetal development. The timing of heart development in relation to birth and the size/electrophysiology of the heart are similar in humans and sheep, providing a model to investigate the repair capacity of the mammalian heart and how this can be applied to adult heart repair. Myocardial infarction was induced by ligation of the left anterior descending coronary artery in fetal (105 days gestation when cardiomyocytes are proliferative) and adolescent sheep (6 mo of age when all cardiomyocytes have switched to an adult phenotype). An ovine gene microarray was used to compare gene expression in sham and infarcted (remote, border and infarct areas) cardiac tissue from fetal and adolescent hearts. The gene response to myocardial infarction was less pronounced in fetal compared with adolescent sheep hearts and there were unique gene responses at each age. There were also region-specific changes in gene expression between each age, in the infarct tissue, tissue bordering the infarct, and tissue remote from the infarction. In total, there were 880 genes that responded to MI uniquely in the adolescent s les compared with 170 genes in the fetal response, as well as 742 overlap genes that showed concordant direction of change responses to infarction at both ages. In response to myocardial infarction, there were specific changes in genes within pathways of mitochondrial oxidation, muscle contraction, and hematopoietic cell lineages, suggesting that the control of energy utilization and immune function are critical for effective heart repair. The more restricted gene response in the fetus may be an important factor in its enhanced capacity for cardiac repair.

Sex differences in uterine artery Doppler during gestation in pregnancies complicated by placental dysfunction.

Publisher: Springer Science and Business Media LLC

Date: 02-02-2021

DOI: 10.1186/S13293-021-00362-7

Abstract: There is growing evidence of sex differences in placental vascular development. The objective of this study was to investigate the effect of fetal sex on uterine artery pulsatility index (PI) throughout gestation in a cohort of normal and complicated pregnancies. A prospective longitudinal study was conducted in 240 pregnant women. Pulsed wave Doppler ultrasound of the proximal uterine arteries was performed at a 4-weekly interval between 14 and 40 weeks of gestation. The patients were classified retrospectively as normal or complicated (one or more of maternal preecl sia, preterm birth, or small for gestational age). To assess if the change in uterine artery PI during gestation differed between normal and complicated pregnancies and between fetal sexes, the uterine artery PI was modeled using a linear function of gestational age and the rate of change was estimated from the slope. While the uterine artery PI did not differ over gestation between females and males for normal pregnancies, the trajectory of this index differed by fetal sex for pregnancies complicated by either preecl sia, preterm birth, or fetal growth restriction ( p 0.0001). The male fetuses in the complicated pregnancy group had an elevated slope compared to the other groups ( p 0.0001), suggesting a more progressive deterioration in uteroplacental perfusion over gestation. The uterine artery PI is widely used to assess uteroplacental function in clinical settings. The observation that this metric changes more rapidly in complicated pregnancies where the fetus was male highlights the importance of sex when interpreting hemodynamic markers of placental maturation.

Feasibility of MRI assessment of maternal–fetal oxygen transport and consumption relative to maternal position in healthy late gestational pregnancies

Publisher: Wiley

Date: 31-10-2023

DOI: 10.1113/JP285097

Intrauterine growth restriction alters the activity of drug metabolising enzymes in the maternal-placental-fetal unit

Publisher: Elsevier BV

Date: 11-2021

DOI: 10.1016/J.LFS.2021.120016

Effect of maternal betamethasone administration on feto-placental vascular resistance in the mouse†.

Publisher: Oxford University Press (OUP)

Date: 18-07-2019

DOI: 10.1093/BIOLRE/IOZ128

Abstract: Antenatal corticosteroids are often administered to women at risk of preterm birth to accelerate fetal lung development however, there is evidence that this treatment may adversely affect placental function in some fetuses. Our group has recently demonstrated that wave reflections in the umbilical artery (UA), measured using high-frequency ultrasound, are sensitive to placental vascular abnormalities. In the present study, we used this approach to investigate the effect of maternal administration of betamethasone, a clinically relevant corticosteroid, on the feto-placental vasculature of the mouse. Fetuses were assessed at embryonic day (E)15.5 and E17.5 in C57BL6/J mice. At both gestational ages, the UA diameter, UA blood flow, and the wave reflection coefficient were significantly elevated in the betamethasone-treated mice compared to vehicle-treated controls. These observations support the interpretation that placental vascular resistance dropped with betamethasone treatment to an extent that could not be explained by vasodilation of the UA alone. Consistent with clinical studies, the effect of betamethasone on UA end-diastolic velocity was heterogeneous. Our results suggest that UA wave reflections are more sensitive to acute changes in placental vascular resistance compared with the UA pulsatility index, and this technique may have clinical application to identify a favorable placental vascular response to fetal therapies such as antenatal corticosteroids, where the fetal heart rate is likely to vary.

Feasibility of ventricular volumetry by cardiovascular MRI to assess cardiac function in the fetal sheep

Publisher: Wiley

Date: 02-06-2020

DOI: 10.1113/JP279054

Redox ratio in the left ventricle of the growth restricted fetus is positively correlated with cardiac output

Publisher: Wiley

Date: 16-09-2021

DOI: 10.1002/JBIO.202100157

Abstract: Intrauterine growth restriction (IUGR) is a result of limited substrate supply to the developing fetus in utero, and can be caused by either placental, genetic or environmental factors. Babies born IUGR can have poor long‐term health outcomes, including being at higher risk of developing cardiovascular disease. Limited substrate supply in the IUGR fetus not only changes the structure of the heart but may also affect metabolism and function of the developing heart. We have utilised two imaging modalities, two‐photon microscopy and phase‐contrast MRI (PC‐MRI), to assess alterations in cardiac metabolism and function using a sheep model of IUGR. Two‐photon imaging revealed that the left ventricle of IUGR fetuses (at 140–141 d GA) had a reduced optical redox ratio, suggesting a reliance on glycolysis for ATP production. Concurrently, the use of PC‐MRI to measure foetal left ventricular cardiac output (LVCO) revealed a positive correlation between LVCO and redox ratio in IUGR, but not control fetuses. These data suggest that altered heart metabolism in IUGR fetuses is indicative of reduced cardiac output, which may contribute to poor cardiac outcomes in adulthood.

Umbilical vein infusion of prostaglandin I₂ increases ductus venosus shunting of oxygen‐rich blood but does not increase cerebral oxygen delivery in the fetal sheep

Publisher: Wiley

Date: 23-08-2020

DOI: 10.1113/JP280019

Fetal hemodynamics and cardiac streaming assessed by 4D flow cardiovascular magnetic resonance in fetal sheep 11 Medical and Health Sciences 1102 Cardiorespiratory Medicine and Haematology

Publisher: Springer Science and Business Media LLC

Date: 21-01-2019

DOI: 10.1186/S12968-018-0512-5

Subcutaneous maternal resveratrol treatment increases uterine artery blood flow in the pregnant ewe and increases fetal but not cardiac growth

Publisher: Wiley

Date: 10-2019

DOI: 10.1113/JP278110

Sex differences in modulation of fetoplacental vascular resistance in growth-restricted mouse fetuses following betamethasone administration: comparisons with human fetuses.

Publisher: Elsevier BV

Date: 2020

DOI: 10.1016/J.AJOGMF.2020.100251

An MRI approach to assess placental function in healthy humans and sheep

Publisher: Wiley

Date: 29-03-2021

DOI: 10.1113/JP281002

Abstract: Human placental function is evaluated using non‐invasive Doppler ultrasound of umbilical and uterine artery pulsatility indices as measures of resistance in placental vascular beds, while measurement of placental oxygen consumption ( ) is only possible during Caesarean delivery. This study shows the feasibility of using magnetic resonance imaging (MRI) in utero to measure blood flow and oxygen content in uterine and umbilical vessels to calculate oxygen delivery to and by the gravid uterus, uteroplacenta and fetus. Normal late gestational human uteroplacental by MRI was ∼4 ml min −1 kg −1 fetal weight, which was similar to our MRI measurements in sheep and to those previously measured using invasive techniques. Our MRI approach can quantify uteroplacental , which involves the quantification of maternal‐ and fetal‐placental blood flows, fetal oxygen delivery and , and the oxygen gradient between uterine‐ and umbilical‐venous blood, providing a comprehensive assessment of placental function with clinical potential. It has not been feasible to perform routine clinical measurement of human placental oxygen consumption ( ) and in vitro studies do not reflect true metabolism in utero . Here we propose an MRI method to non‐invasively quantify in utero placental and fetal oxygen delivery ( ) and in healthy humans and sheep. Women ( n = 20) and Merino sheep ( n = 10 23 sets of measurements) with singleton pregnancies underwent an MRI in late gestation (36 ± 2 weeks and 128 ± 9 days, respectively mean ± SD). Blood flow (phase‐contrast) and oxygen content (T1 and T2 relaxometry) were measured in the major uterine‐ and umbilical‐placental vessels, allowing calculation of uteroplacental and fetal and . Maternal (ml min −1 kg −1 fetus) to the gravid uterus was similar in humans and sheep (human = 54 ± 15, sheep = 53 ± 21, P = 0.854), while fetal (human = 25 ± 4, sheep = 22 ± 5, P = 0.049) was slightly lower in sheep. Uteroplacental and fetal (ml min −1 kg −1 fetus uteroplacental: human = 4.1 ± 1.5, sheep = 3.5 ± 1.9, P = 0.281 fetus: human = 6.8 ± 1.3, sheep = 7.2 ± 1.7, P = 0.426) were similar between species. Late gestational uteroplacental:fetal ratio did not change with age (human, P = 0.256 sheep, P = 0.121). Human umbilical blood flow (ml min −1 kg −1 fetus) decreased with advancing age ( P = 0.008), while fetal was preserved through an increase in oxygen extraction ( P = 0.046). By contrast, sheep fetal was preserved through stable umbilical flow (ml min −1 kg −1 P = 0.443) and oxygen extraction ( P = 0.582). MRI derived measurements of uteroplacental and fetal between humans and sheep were similar and in keeping with prior data obtained using invasive techniques. Taken together, these data confirm the reliability of our approach, which offers a novel clinical ‘placental function test’.

Feasibility of phase-contrast cine magnetic resonance imaging for measuring blood flow in the sheep fetus

Publisher: American Physiological Society

Date: 12-2019

DOI: 10.1152/AJPREGU.00273.2017

Abstract: Phase-contrast cine MRI (PC-MRI) is the gold-standard noninvasive technique for measuring vessel blood flow and has previously been applied in the human fetal circulation. We aimed to assess the feasibility of using PC-MRI to define the distribution of the fetal circulation in sheep. Fetuses were catheterized at 119–120 days of gestation (term, 150 days) and underwent MRI at ∼123 days of gestation under isoflurane anesthesia, ventilated at a [Formula: see text] of 1.0. PC-MRI was performed using a fetal arterial blood pressure catheter signal for cardiac triggering. Blood flows were measured in the major fetal vessels, including the main pulmonary artery, ascending and descending aorta, superior vena cava, ductus arteriosus, left and right pulmonary arteries, umbilical vein, ductus venosus, and common carotid artery and were indexed to estimated fetal weight. The combined ventricular output, pulmonary blood flow, and flow across the foramen ovale were calculated from vessel flows. Intraobserver and interobserver agreement and reproducibility was assessed. Blood flow measurements were successfully obtained in 61 out of 74 vessels (82.4%) interrogated in 9 fetuses. There was good intraobserver [ R = 0.998, P 0.0001 intraclass correlation (ICC) = 0.997] and interobserver agreement ( R = 0.996, P 0.0001 ICC = 0.996). Repeated MRI measurements showed good reproducibility ( R = 0.989, P = 0.0002 ICC = 0.990). We conclude that PC-MRI using fetal catheters for gating triggers is feasible in the major vessels of late gestation fetal sheep. This approach may provide a useful new tool for assessing the circulatory characteristics of fetal sheep models of human disease, including fetal growth restriction and congenital heart disease.

Differential Response to Injury in Fetal and Adolescent Sheep Hearts in the Immediate Post-myocardial Infarction Period

Publisher: Frontiers Media SA

Date: 05-03-2019

DOI: 10.3389/FPHYS.2019.00208

Impact of resveratrol‐mediated increase in uterine artery blood flow on fetal haemodynamics, blood pressure and oxygenation in sheep

Publisher: Wiley

Date: 16-03-2021

DOI: 10.1113/EP089237

Determination of fetal heart rate short-term variation from umbilical artery Doppler waveforms.

Publisher: Wiley

Date: 03-12-2020

DOI: 10.1002/UOG.23145

Abstract: To evaluate the feasibility of using umbilical artery (UA) Doppler waveforms to measure fetal heart rate (FHR) short‐term variation (STV) across gestation. This was a prospective longitudinal study, conducted at two study sites, of 195 pregnancies considered low risk. Pulsed‐wave Doppler of the UAs was performed at 4‐weekly intervals, between 14 and 40 weeks of gestation, using a standardized imaging protocol. Up to 12 consecutive UA Doppler waveforms were analyzed using offline processing software. FHR STV was calculated using average R–R intervals extracted from the waveforms and baseline corrected for FHR. Baseline‐corrected FHR STV increased significantly with gestational age (conditional R 2 = 0.37 P 0.0001) and was correlated inversely with FHR (conditional R 2 = 0.54 P 0.0001). The STV ranged (median (interquartile range)) from 3.5 (2.9–4.1) ms at 14–20 weeks' gestation to 6.3 (4.8–7.7) ms at 34–40 weeks' gestation. The change in heart rate STV did not differ between study sites or in idual sonographers. UA Doppler waveforms offer a robust and feasible method to derive STV of the FHR. It should be emphasized that the UA Doppler‐derived STV is not interchangeable with measurements derived with computerized cardiotocography. Accordingly, further investigations are needed to validate associations with outcome, in order to determine the value of concurrent fetal cardiovascular and heart rate evaluations that are possible with the technique described here. © 2020 International Society of Ultrasound in Obstetrics and Gynecology

Seeing the fetus from a DOHaD perspective: discussion paper from the advanced imaging techniques of DOHaD applications workshop held at the 2019 DOHaD World Congress

Publisher: Cambridge University Press (CUP)

Date: 21-09-2020

DOI: 10.1017/S2040174420000884

Abstract: Advanced imaging techniques are enhancing research capacity focussed on the developmental origins of adult health and disease (DOHaD) hypothesis, and consequently increasing awareness of future health risks across various subareas of DOHaD research themes. Understanding how these advanced imaging techniques in animal models and human population studies can be both additively and synergistically used alongside traditional techniques in DOHaD-focussed laboratories is therefore of great interest. Global experts in advanced imaging techniques congregated at the advanced imaging workshop at the 2019 DOHaD World Congress in Melbourne, Australia. This review summarizes the presentations of new imaging modalities and novel applications to DOHaD research and discussions had by DOHaD researchers that are currently utilizing advanced imaging techniques including MRI, hyperpolarized MRI, ultrasound, and synchrotron-based techniques to aid their DOHaD research focus.

Sex differences in fetal Doppler parameters during gestation.

Publisher: Springer Science and Business Media LLC

Date: 10-03-2021

DOI: 10.1186/S13293-021-00370-7

Abstract: Fetal sex is known to affect pregnancy outcomes. In current clinical practice, monitoring of fetal well-being is based on Doppler ultrasound measurements of major placental and fetal vessels. The objective of this study was to investigate the effect of fetal sex on Doppler parameters throughout gestation in healthy pregnancy. A prospective study was conducted in 240 pregnant women with ultrasound examinations at a 4-weekly interval between 12 and 38 weeks of gestation. Pulsed Doppler spectra were collected for the umbilical arteries (UAs), middle cerebral artery (MCA), descending abdominal aorta (DAo), and ductus venosus (DV). Linear mixed effects models were used to determine if the pulsatility indices (PIs) of these vessels depended on gestational age and fetal sex. While there were no differences in the MCA PI and DV PIV over gestation between female and male fetuses, the trajectory of the UA and DAo PIs differed by fetal sex ( p = 0.02 and p = 0.01, respectively). Doppler ultrasound parameters were found to be dependent on fetal sex for some vessels and not for others in healthy pregnancies. Further investigations are needed to understand the physiological mechanisms for these sex differences and the relevance for disease processes in pregnancy.

Doppler Ultrasound of the Fetal Descending Aorta: An Objective Tool to Assess Placental Blood Flow Resistance in Pregnancies With Discordant Umbilical Arteries.

Publisher: Wiley

Date: 06-07-2021

DOI: 10.1002/JUM.15773

Abstract: To determine the relationship between blood flow in the fetal descending aorta and discordant umbilical arteries (UAs). Pulsed wave Doppler of both UAs and the descending aorta was performed at 4‐weekly intervals between 14 and 40 weeks of gestation in 209 pregnant women. In datasets with discordant UAs, a linear mixed effects model was used to determine the categorical relationship between the UA pulsatility index (PI) (high, low and average) and the descending aorta PI. Of the 209 cases, 81 had a discordance of greater than 25% in UA PI during one of their visits. There were no differences in birth outcomes between the groups with concordant and discordant UA PIs. In the cases with discordant UA PIs, the descending aorta PI was most strongly associated with both the average UA PI ( P = .008), and with the UA with the lower PI ( P = .008). The relationship between blood flow in the descending aorta and UAs is consistent with the law for combining resistances in parallel. Measurements of the descending aorta PI, particularly in a scenario with discordant UAs, may inform the stability of the feto‐placental circulation where discordant UA PIs are found.

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

Publisher: Wiley

Date: 28-08-2022

DOI: 10.1002/ADVS.202203738

Abstract: Magnetic resonance imaging (MRI) assessment of fetal blood oxygen saturation (SO 2 ) can transform the clinical management of high‐risk pregnancies affected by fetal growth restriction (FGR). Here, a novel MRI method assesses the feasibility of identifying normally grown and FGR fetuses in sheep and is then applied to humans. MRI scans are performed in pregnant ewes at 110 and 140 days (term = 150d) gestation and in pregnant women at 28 +3 ± 2 +5 weeks to measure feto‐placental SO 2 . Birth weight is collected and, in sheep, fetal blood SO 2 is measured with a blood gas analyzer (BGA). Fetal arterial SO 2 measured by BGA predicts fetal birth weight in sheep and distinguishes between fetuses that are normally grown, small for gestational age, and FGR. MRI feto‐placental SO 2 in late gestation is related to fetal blood SO 2 measured by BGA and body weight. In sheep, MRI feto‐placental SO 2 in mid‐gestation is related to fetal SO 2 later in gestation. MRI feto‐placental SO 2 distinguishes between normally grown and FGR fetuses, as well as distinguishing FGR fetuses with and without normal Doppler in humans. Thus, a multi‐compartment placental MRI model detects low placental SO 2 and distinguishes between small hypoxemic fetuses and normally grown fetuses.

Normal human and sheep fetal vessel oxygen saturations by T2 magnetic resonance imaging

Publisher: Wiley

Date: 29-05-2020

DOI: 10.1113/JP279725

Open or closed: Changes in ductus arteriosus flow patterns at birth using 4D flow MRI in newborn piglets

Publisher: Wiley

Date: 26-08-2021

DOI: 10.14814/PHY2.14999

Hospital For Sick Children

Location: Canada

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Université Paul Sabatier

Location: France

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UNIVERSIDAD DE CHILE

Location: Chile

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University Of Toronto

Location: Canada

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University Of British Columbia

Location: Canada

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Discovery Projects - Grant ID: DP190102263

Start Date: 2019

End Date: 12-2021

Amount: $550,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP220103289

Start Date: 2022

End Date: 12-2024

Amount: $686,263.00

Funder: Australian Research Council