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Maternal and neonatal outcomes.
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Introduction
We aimed to explore the use of magnetic resonance imaging (MRI) in vivo as a tool to elucidate the placental phenotype in women with chronic hypertension.
Methods
In case-control study, women with chronic hypertension and those with uncomplicated pregnancies were imaged using either a 3T Achieva or 1.5T Ingenia scanner. T2-weighted im...
Contexts in source publication
Context 1
... Table 1). Four out of 43 women (9%) with chronic hypertension developed superimposed preeclampsia (Table 2, Supplemental Table S2). Nine (21%) of women with chronic hypertension delivered prematurely compared with no preterm deliveries in the control group (Table 2, Supplemental Table S2). ...Context 2
... out of 43 women (9%) with chronic hypertension developed superimposed preeclampsia (Table 2, Supplemental Table S2). Nine (21%) of women with chronic hypertension delivered prematurely compared with no preterm deliveries in the control group (Table 2, Supplemental Table S2). 38 (88%) of women with chronic hypertension had a planned delivery (pre-labour caesarean section or induction of labour) compared to 32 (37%) in the control group (Table 2, Supple- mental Table S2). ...Context 3
... (21%) of women with chronic hypertension delivered prematurely compared with no preterm deliveries in the control group (Table 2, Supplemental Table S2). 38 (88%) of women with chronic hypertension had a planned delivery (pre-labour caesarean section or induction of labour) compared to 32 (37%) in the control group (Table 2, Supple- mental Table S2). ...Context 4
... placentas were examined after delivery (24 from women with chronic hypertension, 44 from controls) ( Table 2). Five out of six placentae with maternal vascular malperfusion features on histological examination were from women with chronic hypertension ( Table 2). ...Similar publications
Simple Summary
Pre-treatment (TX) prediction of the risk of locoregional failure (LRF) will allow for TX individualization in patients with nasopharyngeal carcinoma (NPC). The aim of the present study was to identify whether the quantitative metrics from pre-TX non-Gaussian intravoxel incoherent motion (NGIVIM) diffusion weighted (DW-) and fast exc...
Citations
... PE placentas exhibit injuries such as placental vascular lesions and vesicular fibrosis, syncytial knots and microcalcifications, and perivillous fibrin deposition and villous infarcts. These findings explain the increased placental stiffness seen in PE [25][26][27]. ADC has been reported to be lower in abnormal placentas than in normal placentas. Restricted diffusion may result from reduced gas exchange area in PE-complicated placentas [28,29]. ...
... In particular, this has proven valuable in improving our understanding of the human placenta, an organ for which there were previously very limited methods for in vivo study. The application of T2*-relaxometry has offered important insights into both physiological placental development across gestation 1-3 , as well as abnormal placentation as seen in pregnancies affected by hypertensive diseases 2,4,5 , prior to spontaneous preterm birth 6 , fetal growth restriction and discordant growth in twins 7,8 albeit in small cohorts. A rst multi-center study was recently published 1 . ...
Placental MRI is increasingly implemented in clinical obstetrics and research. Functional imaging, especially T2*, has been shown to vary across gestation and in pathology. Translation into the clinical arena has been slow because of time taken to mask the region of interest and owing to differences in T2* results depending on field strength. This paper contributes methodology to remove these barriers by utilising data from 0.55, 1.5 and 3T MRI to provide a fully automated segmentation tool; determining field strength dependency of placental assessment techniques; and deriving normal ranges for T2* by gestational age but independent of field strength. T2* datasets were acquired across field strengths. Automatic quantification including fully automatic masking was achieved and tested in 270 datasets across fields. Normal curves for quantitative placental mean T2*, volume and other derived measurements were obtained in 273 fetal MRI scans and z-scores calculated. The fully automatic segmentation achieved excellent quantification results (Dice scores of 0.807 at 3T, 0.796 at 1.5T and 0.815 at 0.55T.). Similar changes were seen between placental T2* and gestational age across all three field strengths (p < 0.05). Z-scores were generated. This study provides confidence in the translatability of T2* trends across field strengths in fetal imaging.
... 40,41 Work using combined placental T * 2 ADC measurements has also identified differences, when compared to controls, in pregnancies affected by preeclampsia, 1 chronic hypertension. 42 Establishing reference ranges for absolute T * 2 and ADC values of the placenta in normal pregnancy is important when considering how they are affected by placental pathology. ...
... ADC maps are already used to help describe placental heterogeneity and to aid in the characterization of conditions such as placental abruption and gestational trophoblastic disease. 50 As highlighted earlier, placental ADC and T * 2 values have been shown to be lower in fetuses with placental insufficiency and IUGR, 1,3,12,38,40,42 although there is minimal work investigating how these differences evolve over gestation when compared to normal pregnancies. ...
Purpose
Studying placental development informs when development is abnormal. Most placental MRI studies are cross‐sectional and do not study the extent of individual variability throughout pregnancy. We aimed to explore how diffusion MRI measures of placental function and microstructure vary in individual healthy pregnancies throughout gestation.
Methods
Seventy‐nine pregnant, low‐risk participants (17 scanned twice and 62 scanned once) were included. T2‐weighted anatomical imaging and a combined multi‐echo spin‐echo diffusion‐weighted sequence were acquired at 3 T. Combined diffusion–relaxometry models were performed using both a T2*$$ {\mathrm{T}}_2^{\ast } $$‐ADC and a bicompartmental T2*$$ {\mathrm{T}}_2^{\ast } $$‐intravoxel‐incoherent‐motion (T2*IVIM$$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$) model fit.
Results
There was a significant decline in placental T2*$$ {\mathrm{T}}_2^{\ast } $$ and ADC (both P < 0.01) over gestation. These declines are consistent in individuals for T2*$$ {\mathrm{T}}_2^{\ast } $$ (covariance = −0.47), but not ADC (covariance = −1.04). The T2*IVIM$$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$ model identified a consistent decline in individuals over gestation in T2*$$ {\mathrm{T}}_2^{\ast } $$ from both the perfusing and diffusing placental compartments, but not in ADC values from either. The placental perfusing compartment fraction increased over gestation (P = 0.0017), but this increase was not consistent in individuals (covariance = 2.57).
Conclusion
Whole placental T2*$$ {\mathrm{T}}_2^{\ast } $$ and ADC values decrease over gestation, although only T2*$$ {\mathrm{T}}_2^{\ast } $$ values showed consistent trends within subjects. There was minimal individual variation in rates of change of T2*$$ {\mathrm{T}}_2^{\ast } $$ values from perfusing and diffusing placental compartments, whereas trends in ADC values from these compartments were less consistent. These findings probably relate to the increased complexity of the bicompartmental T2*IVIM$$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$ model, and differences in how different placental regions evolve at a microstructural level. These placental MRI metrics from low‐risk pregnancies provide a useful benchmark for clinical cohorts.
... Both T * 2 and diffusion MRI have been successfully used for placental assessment in vivo to visualize and quantify microstructural differences in conditions such as chronic hypertension, preeclampsia, 10,11,12 and fetal growth restriction. 13,14 There has been recent focus on the IVIM model, showing increased perfusion fraction inside the placental parenchyma compared to control cases, 15 reduced perfusion fraction in placentae with evidence of fetal vascular malperfusion, 16 and reduced birth weight, 17,18 as well good robustness of the placental perfusion fraction measurements. ...
Purpose
Preterm premature rupture of membranes complicates up to 40% of premature deliveries. Fetal infection may occur in the absence of maternal symptoms, delaying diagnosis and increasing morbidity and mortality. A noninvasive antenatal assessment of early signs of placental inflammation is therefore urgently required.
Methods
Sixteen women with preterm premature rupture of membranes < 34 weeks gestation and 60 women with uncomplicated pregnancies were prospectively recruited. A modified diffusion‐weighted spin‐echo single shot EPI sequence with a diffusion preparation acquiring 264 unique parameter combinations in < 9 min was obtained on a clinical 3 Tesla MRI scanner. The data was fitted to a 2‐compartment T2*$$ {\mathrm{T}}_2^{\ast } $$‐intravoxel incoherent motion model comprising fast and slowly circulating fluid pools to obtain quantitative information on perfusion, density, and tissue composition. Z values were calculated, and correlation with time from between the rupture of membranes and the scan, gestational age at delivery, and time between scan and delivery assessed.
Results
Placental T2*$$ {\mathrm{T}}_2^{\ast } $$ was significantly reduced in preterm premature rupture of membranes, and the 2‐compartmental model demonstrated that this decline is mainly linked to the perfusion component observed in the placental parenchyma. Multi‐modal MRI measurement of placental function is linked to gestational age at delivery and time from membrane rupture.
Conclusion
More complex models and data acquisition can potentially improve fitting of the underlying etiology of preterm birth compared with individual single‐contrast models and contribute to additional insights in the future. This will need validation in larger cohorts. A multi‐modal MRI acquisition between rupture of the membranes and delivery can be used to measure placental function and is linked to gestational age at delivery.
... 4,5 Relatively few studies of placental MRI define the range of normal appearances. [9][10][11][12][13] The published reports of placental MRI appearances commenced with case reports 4,8 and subsequently small case series, 7,14,15 typically where the MRI was supplementary to abnormal ultrasound scans. Systematic reviews and meta-analyses of the MRI appearances of PAS have been published 16,17 , but study populations are invariably filtered by antecedent abnormal or non-diagnostic ultrasound examinations. ...
... Few studies have reported on normal MRI placental appearances based on scanning low-risk pregnancies, with normal appearances inferred by knowledge of normal ultrasound appearances and observational studies on scans for foetal abnormalities. [9][10][11][12][13] This study was designed to assess the MRI appearances of the placenta in normal pregnancies. The frequency of MRI appearances associated with PAS in low-risk pregnancies with macroscopically normal placentae post-delivery was also assessed. ...
... T2 heterogeneity is observed in abnormal placentae as well as normal maturation, and also visible on ultrasound. 12,18,19 Placental T2 heterogeneity can be variably defined and reported, either as a binary outcome or categorised as mildly, moderately or markedly T2 heterogeneous. 27 The presence of normal T2-dark thin septa between cotyledons is not a sign of T2 heterogeneity. ...
Introduction:
The MRI appearances of the human placenta in the absence of maternal or fetal pathology have not been extensively studied, with only a few studies reporting findings in the uncomplicated pregnancy. The purpose of this study is to review the placental MRI appearances in low-risk pregnancies in a prospective study.
Methods:
A prospective observational study of placental MRI in low-risk pregnancies was initially planned, however recruitment was terminated early due to the COVID19 pandemic. The protocol was subsequently modified to compare the placental appearances in the enrolled cohort with pregnancies having had MRI for non-placental pathologies. The data from the two groups were then pooled to assess the range of normal placental appearances.
Results:
Eighty-three pregnancies were prospectively assessed with MRI at a median gestation of 29 weeks (range 14-39) from a mixed group of prospective cases (n = 28) and retrospectively recruited obstetric MRI (n = 55). Placental thickness in the third trimester ranged from 18 to 35 mm. T2 heterogeneity was seen in 75% (25/33) at second trimester and by the third trimester 50% (25/50) were moderately or markedly heterogenous. T2 dark bands (>6 mm) were seen in 9% (3/33) and 20% (10/50) of second and third trimester pregnancies, respectively. Undetectable myometrium or loss of the subplacental myometrial plane was present in 15% (5/33) of second and 38% (19/50) of third trimester placentae.
Conclusion:
This qualitative study of normal placental MRI appearances expands the current knowledge base by confirming they vary, evolve with gestation, and can overlap with signs of placenta accreta spectrum.
... Placental assessment during pregnancy is hampered by difficulties in isolating the feto-placental compartment. Magnetic Resonance Imaging (MRI) was recently able to identify highly distinctive signatures of placentas from women with pre-eclampsia [7] and chronic hypertension [8]. This includes decreased mean diffusivity, indicative of changes in the placental microstructure such as the density of the villous trees [9,10] and reduced T2*, related to placental oxygenation via the paramagnetic properties of deoxygenated haemoglobin. ...
... studies [7,22,27]. The illustrated spread of results in the chronic hypertension cohort, shown previously [8] was confirmed in the CARP data but not analysed as a cohort here due to the limited numbers. The observed changes agree well with similar results shown in a cohort of women with fetal growth restriction and placental insufficiency [22,28]. ...
Introduction
The CARP study aims to investigate placental function, cardiac function and fetal growth comprehensively during pregnancy, a time of maximal cardiac stress, to work towards disentangling the complex cardiac and placental interactions presenting in the aetiology of pre-eclampsia as well as predicting maternal Cardiovascular Disease (CVD) risk in later life.
Background
The involvement of the cardiovascular system in pre-eclampsia, one of the most serious complications of pregnancy, is evident. While the manifestations of pre-eclampsia during pregnancy (high blood pressure, multi-organ disease, and placental dysfunction) resolve after delivery, a lifelong elevated CVD risk remains.
Method
An assessment including both cardiac and placental Magnetic Resonance Imaging (MRI) optimised for use in pregnancy and bespoke to the expected changes was developed. Simultaneous structural and functional MRI data from the placenta, the heart and the fetus were obtained in a total of 32 pregnant women (gestational ages from 18.1 to 37.5 weeks), including uncomplicated pregnancies and five cases with early onset pre-eclampsia.
Results
The achieved comprehensive MR acquisition was able to demonstrate a phenotype associated with pre-eclampsia linking both placental and cardiac factors, reduced mean T2* (p < 0.005), increased heterogeneity (p < 0.005) and a trend towards an increase in cardiac work, larger average mass (109.4 vs 93.65 gr), wall thickness (7.0 vs 6.4 mm), blood pool volume (135.7 vs 127.48 mL) and mass to volume ratio (0.82 vs 0.75). The cardiac output in the controls was, controlling for gestational age, positively correlated with placental volume (p < 0.05).
Discussion
The CARP study constitutes the first joint assessment of functional and structural properties of the cardiac system and the placenta during pregnancy. Early indications of cardiac remodelling in pre-eclampsia were demonstrated paving the way for larger studies.
BACKGROUND
Preeclampsia is a multiorgan disease of pregnancy that has short- and long-term implications for the woman and fetus, whose immediate impact is poorly understood. We present a novel multiorgan approach to magnetic resonance imaging (MRI) investigation of preeclampsia, with the acquisition of maternal cardiac, placental, and fetal brain anatomic and functional imaging.
METHODS
An observational study was performed recruiting 3 groups of pregnant women: those with preeclampsia, chronic hypertension, or no medical complications. All women underwent a cardiac MRI, and pregnant women underwent a placental-fetal MRI. Cardiac analysis for structural, morphological, and flow data were undertaken; placenta and fetal brain volumetric and T2* (which describes relative tissue oxygenation) data were obtained. All results were corrected for gestational age. A nonpregnant cohort was identified for inclusion in the statistical shape analysis.
RESULTS
Seventy-eight MRIs were obtained during pregnancy. Cardiac MRI analysis demonstrated higher left ventricular mass in preeclampsia with 3-dimensional modeling revealing additional specific characteristics of eccentricity and outflow track remodeling. Pregnancies affected by preeclampsia demonstrated lower placental and fetal brain T2*. Within the preeclampsia group, 23% placental T2* results were consistent with controls, these were the only cases with normal placental histopathology. Fetal brain T2* results were consistent with normal controls in 31% of cases.
CONCLUSIONS
We present the first holistic assessment of the immediate implications of preeclampsia on maternal heart, placenta, and fetal brain. As well as having potential clinical implications for the risk stratification and management of women with preeclampsia, this gives an insight into the disease mechanism.
The placenta plays a critical role in fetal development. It serves as a multi-functional organ that protects and nurtures the fetus during pregnancy. However, despite its importance, the intricacies of placental structure and function in normal and diseased states have remained largely unexplored. Thus, in 2014, the National Institute of Child Health and Human Development launched the Human Placenta Project (HPP). As of May 2023, the HPP has awarded over $101 million in research funds, resulting in 41 funded studies and 459 publications. We conducted a comprehensive review of these studies and publications to identify areas of funded research, advances in those areas, limitations of current research, and continued areas of need. This paper will specifically review the funded studies by the HPP, followed by an in-depth discussion on advances and gaps within placental-focused imaging. We highlight the progress within magnetic reasonance imaging and ultrasound, including development of tools for the assessment of placental function and structure.
Background
Pre-eclampsia is a multiorgan disease of pregnancy that has short- and long-term implications for the woman and fetus, whose immediate impact is poorly understood. We present a novel multi-system approach to MRI investigation of pre-eclampsia, with acquisition of maternal cardiac, placental, and fetal brain anatomical and functional imaging.
Methods
A prospective study was carried out recruiting pregnant women with pre-eclampsia, chronic hypertension, or no medical complications, and a non-pregnant female cohort. All women underwent a cardiac MRI, and pregnant women underwent a fetal-placental MRI. Cardiac analysis for structural, morphological and flow data was undertaken; placenta and fetal brain volumetric and T2* data were obtained. All results were corrected for gestational age.
Results
Seventy-eight MRIs were obtained during pregnancy. Pregnancies affected by pre-eclampsia demonstrated lower placental and fetal brain T2*. Within the pre-eclampsia group, three placental T2* results were within the normal range, these were the only cases with normal placental histopathology. Similarly, three fetal brain T2* results were within the normal range; these cases had no evidence of cerebral redistribution on fetal Dopplers. Cardiac MRI analysis demonstrated higher left ventricular mass in pre-eclampsia with 3D modelling revealing additional specific characteristics of eccentricity and outflow track remodelling.
Conclusions
We present the first holistic assessment of the immediate implications of pre-eclampsia on the placenta, maternal heart and fetal brain. As well as having potential clinical implications for the risk-stratification and management of women with pre-eclampsia, this gives an insight into disease mechanism.
