Assessment of the Placenta in Intrauterine Growth Restriction by Diffusion-Weighted Imaging and Proton Magnetic Resonance Spectroscopy

Association of cord plasma metabolites with birth weight: results from metabolomic and lipidomic studies of discovery and validation cohorts

OBJECTIVE

Birth weight is a good predictor of fetal intrauterine growth and long-term health, and several studies have evaluated the relationship between metabolites and birth weight. The aim of this study was to investigate the association of cord blood metabolomics and lipidomics with birth weight, using a two-stage discovery and validation approach.

METHODS

Firstly, a pseudotargeted metabolomics approach was applied to detect metabolites in 504 cord blood samples in the discovery set enrolled from the Wuhan Healthy Baby Cohort, China. Metabolome-wide association scan analysis and pathway enrichment were applied to identify metabolites and metabolic pathways that were significantly associated with birth weight adjusted for gestational age Z-score (BW Z-score). Logistic regression models were used to analyze the association of metabolites in the most significantly associated pathways with small-for-gestational age (SGA) at delivery and low birth weight (LBW). Subsequently, 350 cord blood samples in a validation cohort were subjected to targeted analysis to validate the metabolites identified by screening in the discovery cohort.

RESULTS

In the discovery set, of 2566 metabolites detected, 2418 metabolites were retained for subsequent analysis after data preprocessing. Of these, 513 metabolites were significantly associated with BW Z-score (P-value adjusted for false discovery rate (PFDR) < 0.05), of which 298 Kyoto Encyclopedia of Genes and Genomes (KEGG)-annotated metabolites were included in the pathway analysis. The primary bile acid biosynthesis pathway was the most relevant metabolic pathway associated with BW Z-score. Elevated cord plasma primary bile acids were associated with lower BW Z-score and higher risk of SGA or LBW in the discovery and validation cohorts. In the validation set, a 2-fold increase in taurochenodeoxycholic acid (TCDCA) and in taurocholic acid (TCA) was associated with a decrease in BW Z-score (estimated β coefficient, -0.10 (95% CI, -0.20 to 0.00) and -0.18 (95% CI, -0.31 to -0.04), respectively), after adjusting for covariates. In addition, a 2-fold increase in cord plasma TCDCA and of cord plasma TCA was associated with an increased risk of SGA (adjusted odds ratio (OR), 1.52 (95% CI, 1.00-2.30) and 1.77 (95% CI, 1.05-2.98), respectively). The adjusted OR for LBW, for a 2-fold increase in TCDCA and TCA concentration, were 2.39 (95% CI, 1.00-5.71) and 3.21 (95% CI, 0.96-10.74), respectively.

CONCLUSIONS

These results indicate a significant association of elevated primary bile acids, particularly TCDCA and TCA, in cord blood with lower BW Z-score, as well as increased risk of SGA and LBW. Abnormalities of primary bile acid metabolism may play an important role in restricted fetal development. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Non-invasive mapping of human placenta microenvironments throughout pregnancy with diffusion-relaxation MRI

INTRODUCTION

In-vivo measurements of placental structure and function have the potential to improve prediction, diagnosis, and treatment planning for a wide range of pregnancy complications, such as fetal growth restriction and pre-eclampsia, and hence inform clinical decision making, ultimately improving patient outcomes. MRI is emerging as a technique with increased sensitivity to placental structure and function compared to the current clinical standard, ultrasound.

METHODS

We demonstrate and evaluate a combined diffusion-relaxation MRI acquisition and analysis pipeline on a sizable cohort of 78 normal pregnancies with gestational ages ranging from 15 + 5 to 38 + 4 weeks. Our acquisition comprises a combined T2*-diffusion MRI acquisition sequence - which is simultaneously sensitive to oxygenation, microstructure and microcirculation. We analyse our scans with a data-driven unsupervised machine learning technique, InSpect, that parsimoniously identifies distinct components in the data.

RESULTS

We identify and map seven potential placental microenvironments and reveal detailed insights into multiple microstructural and microcirculatory features of the placenta, and assess their trends across gestation.

DISCUSSION

By demonstrating direct observation of micro-scale placental structure and function, and revealing clear trends across pregnancy, our work contributes towards the development of robust imaging biomarkers for pregnancy complications and the ultimate goal of a normative model of placental development.

Developments in functional imaging of the placenta

The placenta is both the literal and metaphorical black box of pregnancy. Measurement of the function of the placenta has the potential to enhance our understanding of this enigmatic organ and serve to support obstetric decision making. Advanced imaging techniques are key to support these measurements. This review summarises emerging imaging technology being used to measure the function of the placenta and new developments in the computational analysis of these data. We address three important examples where functional imaging is supporting our understanding of these conditions: fetal growth restriction, placenta accreta, and twin-twin transfusion syndrome.

Low-Field Combined Diffusion-Relaxation MRI for Mapping Placenta Structure and Function

Purpose

Demonstrating quantitative multi-parametric mapping in the placenta with combined T 2 ∗ -diffusion MRI at low-field (0.55T).

Methods

We present 57 placental MRI scans performed on a commercially available 0.55T scanner. We acquired the images using a combined T 2 ∗ -diffusion technique scan that simultaneously acquires multiple diffusion preparations and echo times. We processed the data to produce quantitative T 2 ∗ and diffusivity maps using a combined T 2 ∗ -ADC model. We compared the derived quantitative parameters across gestation in healthy controls and a cohort of clinical cases.

Results

Quantitative parameter maps closely resemble those from previous experiments at higher field strength, with similar trends in T 2 ∗ and ADC against gestational age observed.

Conclusion

Combined T 2 ∗ -diffusion placental MRI is reliably achievable at 0.55T. The advantages of lower field strength - such as cost, ease of deployment, increased accessibility and patient comfort due to the wider bore, and increased T 2 ∗ for larger dynamic ranges - can support the widespread roll out of placental MRI as an adjunct to ultrasound during pregnancy.

Predicting the risk of fetal growth restriction by radiomics analysis of the placenta on T2WI: A retrospective case-control study

INTRODUCTION

Fetal growth restriction (FGR) is associated with placental abnormalities, and its precise diagnosis is challenging. This study aimed to explore the role of radiomics based on placental MRI in predicting FGR.

METHODS

A retrospective study using T2-weighted placental MRI data were conducted. A total of 960 radiomic features were automatically extracted. Features were selected using three-step machine learning methods. A combined model was constructed by combining MRI-based radiomic features and ultrasound-based fetal measurements. The receiver operating characteristic curves (ROC) were conducted to assess model performance. Additionally, decision curves and calibration curves were performed to evaluate prediction consistency of different models.

RESULTS

Among the study participants, pregnant women who delivered from January 2015 to June 2021 were randomly divided into training (n = 119) and test (n = 40) sets. Forty-three other pregnant women who delivered from July 2021 to December 2021 were used as the time-independent validation set. After training and testing, three radiomic features that were strongly correlated with FGR were selected. The area under the ROC curves (AUCs) of the MRI-based radiomics model reached 0.87 (95% confidence interval [CI]: 0.74-0.96) and 0.87 (95% CI: 0.76-0.97) in the test and validation sets, respectively. Moreover, the AUCs for the model comprising MRI-based radiomic features and ultrasound-based measurements were 0.91 (95% CI: 0.83-0.97) and 0.94 (95% CI: 0.86-0.99) in the test and validation sets, respectively.

DISCUSSION

MRI-based placental radiomics could accurately predict FGR. Moreover, combining placental MRI-based radiomic features with ultrasound indicators of the fetus could improve the diagnostic accuracy of FGR.

Differences in placental oxygenation and perfusion status between fetal growth-restricted and small-for-gestational-age pregnancies: a functional magnetic resonance imaging study

OBJECTIVE

Functional magnetic resonance imaging (MRI) can assess oxygenation and perfusion status in the placenta. We aimed to explore the differences in functional parameters between pregnancies complicated by fetal growth restriction (FGR) and small-for-gestational-age (SGA).

METHODS

This was a prospective study. A pregnancy complicated by SGA was defined by prenatal ultrasonic estimated fetal weight (EFW) and a final birthweight < the 10th percentile. A pregnancy complicated by FGR was defined as a more severe subtype (ultrasonic EFW < the 3rd percentile or abnormal Doppler results). All pregnant women underwent T2* and intravoxel incoherent motion (IVIM) scans using a 3.0-T MRI scanner. Functional parameters in the control, SGA, and FGR groups, namely, the T2* Z score, apparent diffusion coefficient (ADC), diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f), were calculated and compared.

RESULTS

In total, 30 pregnancies complicated by SGA, 24 pregnancies complicated by FGR, and 28 control pregnancies were included in the final analysis. Oxygenation status, as assessed by the T2* Z score, was significantly lower in pregnancies complicated by FGR than in pregnancies complicated by SGA (p < 0.001). However, diffusion and perfusion parameters, including the ADC, D, D*, and f, were similar between pregnancies complicated by SGA and FGR (p > 0.05 for all). Compared to the control pregnancies, all the parameters were significantly decreased in the SGA and FGR groups, except for the D* value. The T2* Z score, ADC, and D values were negatively correlated with birthweight.

CONCLUSION

Although both pregnancies complicated by SGA and FGR were associated with significantly lower oxygenation and perfusion than normal control pregnancies, placental hypoxia seemed to be more predominant in pregnancies complicated by FGR than in pregnancies complicated by SGA.

KEY POINTS

• Pregnancy complicated by FGR was associated with a more severe type of hypoxia than pregnancy complicated by SGA. • The diffusion and perfusion parameters of pregnancies complicated by SGA and FGR were similar. • SGA may represent another growth disorder that is not entirely healthy.

Differentiating between normal and fetal growth restriction-complicated placentas: is T2∗ imaging imaging more accurate than conventional diffusion-weighted imaging?

AIM

To compare the performance of T2∗ imaging and apparent diffusion coefficient (ADC) in differentiating normal placentas from those complicated by fetal growth restriction (FGR).

MATERIALS AND METHODS

This prospective study included 28 control and 30 FGR placentas. Gradient-echo magnetic resonance imaging (MRI) at 16 different echo times and diffusion-weighted imaging (b-value of 0 and 800 s/mm²) were performed on all pregnant women using a 3 T MRI system.

RESULTS

Both T2∗ imaging Z-score and ADC were significantly lower in the FGR placentas (ADC, (1.69 ± 0.19) × 10^-3 versus (1.42 ± 0.28) × 10^-3 mm²/s, p<0.001; T2∗ imaging Z-score, -0.004 ± 0.95 versus -2.441 ± 1.48, p<0.001). The area under the curve for T2∗ imaging Z-score and ADC was 0.917 (95% confidence interval [CI] = 0.842-0.991) and 0.788 (95% CI = 0.655-0.887), respectively. The performance of T2∗ imaging in differentiating FGR placentas was significantly better than that of ADC (Z = 2.043, p=0.041).

CONCLUSION

Placental T2∗ imaging was found to be more reliable than ADC in differentiating between normal and FGR placentas.

The association of serum total bile acid with new-onset hypertension during pregnancy

Background

There has been considerable interest in the interrelationship between the liver and hypertension. The relationship between serum total bile acid (TBA) and hypertension has been reported. Moreover, intrahepatic cholestasis of pregnancy was correlated to gestation hypertension. However, the association between maternal serum TBA level in the normal range and new-onset hypertension disorders during pregnancy remains unclear. The present study aimed to evaluate the relationship between maternal serum TBA level in the normal range and the risk, disease severity and adverse pregnancy outcomes of new-onset hypertension during pregnancy.

Method

Using the electronic medical records on all pregnant women from the Department of Obstetrics and Gynecology, Third Affiliated Hospital of Guangzhou Medical University, between 2014 and 2020, we conducted a retrospective cohort study of 2581 singleton pregnant women with maternal serum TBA levels in the normal range. Patients were grouped into the non-hypertension during pregnancy (1071), gestational hypertension (480) and preeclampsia (1030) groups.

Result

We found that maternal serum TBA levels were significantly higher in the preeclampsia and gestational hypertension groups than in the non-hypertension group (p < 0.01). Multiple logistic regression analysis showed that TBA level was independently and significantly associated with preeclampsia and gestational hypertension (odds ratio: 1.37, 95% confidence interval [CI]: 1.27–1.48, p = 0.001, odds ratio: 1.34, 95% confidence interval [CI]: 1.24–1.46, p = 0.005, respectively). Moreover, elevated TBA level was positively associated with the risk of severe PE and negatively with mild PE (p < 0.01). In addition, maternal serum TBA levels were negatively related to birth weight (p < 0.001).

Conclusions

These results suggest that maternal serum TBA in the normal range also might be a valuable biomarker for disease severity in preeclampsia and gestational hypertension. Additionally, our results also indicate associations of serum total bile acid levels in the normal range with an increased risk of fetal growth restriction and low birth weight among offspring. These results suggest that TBA could serve as a prognostic biomarker for new-onset hypertension during pregnancy.

Assessment of placental abruption with diffusion-weighted imaging

AIM

To investigate whether placental abruption without fetal distress could be assessed by apparent diffusion coefficient (ADC) values in magnetic resonance imaging (MRI).

METHODS

We conducted a retrospective case-control study at a single center. ADC values at the lesions of placental abruption in the abruption group (n = 8) were compared to those in the control group (n = 32). In the abruption group, ADC values at the sites of abruption were also compared to those at the nonabruption sites within the same placenta.

RESULTS

The ADC values in the placental area above the abruption site in the abruption group showed lower values than those in the control group when the slice containing the umbilical cord insertion site was set as the reference, and those values were compared in each corresponding slice. Compared with average ADC values, those above the abruption site in the abruption group were also significantly lower than those in the control group (p < 0.001). Furthermore, ADC values at the area above abruption were lower than those at the nonabruption area of all planes in the abruption group.

CONCLUSIONS

ADC values at the lesions above the placental abruption site were reduced compared to those in the normal placenta and those in the nonabruption area. Thus, it would be helpful to understand the pathophysiology of placental abruption in expectant management, although further investigations would be needed.

Emerging placental biomarkers of health and disease through advanced magnetic resonance imaging (MRI)

Placental dysfunction is a major cause of fetal demise, fetal growth restriction, and preterm birth, as well as significant maternal morbidity and mortality. Infant survivors of placental dysfunction are at elevatedrisk for lifelong neuropsychiatric morbidity. However, despite the significant consequences of placental disease, there are no clinical tools to directly and non-invasively assess and measure placental function in pregnancy. In this work, we will review advanced MRI techniques applied to the study of the in vivo human placenta in order to better detail placental structure, architecture, and function. We will discuss the potential of these measures to serve as optimal biomarkers of placental dysfunction and review the evidence of these tools in the discrimination of health and disease in pregnancy. Efforts to advance our understanding of in vivo placental development are necessary if we are to optimize healthy pregnancy outcomes and prevent brain injury in successive generations. Current management of many high-risk pregnancies cannot address placental maldevelopment or injury, given the standard tools available to clinicians. Once accurate biomarkers of placental development and function are constructed, the subsequent steps will be to introduce maternal and fetal therapeutics targeting at optimizing placental function. Applying these biomarkers in future studies will allow for real-time assessments of safety and efficacy of novel interventions aimed at improving maternal-fetal well-being.

Association of Elevated Maternal Serum Total Bile Acids With Low Birth Weight and Intrauterine Fetal Growth Restriction

IMPORTANCE

Bile acids play essential roles in metabolic modulation. Excessive serum total bile acid (sTBA) levels during pregnancy are associated with adverse perinatal outcomes; however, their association with the risk of intrauterine growth restriction (IUGR) remains unclear.

OBJECTIVE

To investigate the association between maternal sTBA concentration during pregnancy and the risk of IUGR.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included pregnant individuals who delivered live singleton neonates and had regular antenatal examination records available at a hospital-based center in Shanghai, China, from 2014 to 2018. Data were analyzed from July to November 2020.

EXPOSURES

Maternal sTBA concentration during pregnancy.

MAIN OUTCOMES AND MEASURES

Fetal birth weight and probability of low birth weight (LBW) and IUGR.

RESULTS

This study included 68 245 singleton pregnancies with live births for analysis. The mean (SD) age of the pregnant individuals was 30.5 (3.8) years, 67 168 patients (98.4%) were Han, and 50 155 (73.5%) were nulliparous. Nonlinear regression models suggested that there was an inverted J-shaped association between maternal sTBA level during pregnancy and fetal birth weight, with a steep decrease in birth weight at high sTBA levels (estimated mean [SE] birth weight for sTBA of 40.8 ug/mL, 2879 [39.9] g) and greater birth weights at lower sTBA levels (estimated mean [SE] birth weight for sTBA 0.4 μg/mL, 3290 [3.9] g; and for 4.1 μg/mL, 3334 [1.6] g). Lower birth weight and a higher incidence of IUGR were observed in patients with gestational hypercholanemia (sTBA ≥4.08 μg/mL) compared with those without gestational hypercholanemia (birth weight: estimated adjusted mean [SE], 3309 [3.32] vs 3338 [0.80] g; P = .005; incidence of IUGR: 62 of 4467 [1.4%] vs 312 of 63 778 [0.5%]; P < .001). Moreover, compared with patients with sTBA concentrations of less than 4.08 μg/mL, those with gestational hypercholanemia had an increased risk of LBW (adjusted odds ratio [aOR], 1.29; 95% CI, 1.09-1.53) and IUGR (aOR, 2.18; 95% CI, 1.62-2.91). In addition, there was an additive interaction between hypertensive disorders in pregnancy (HDP) and hypercholanemia on LBW and IUGR risk. The highest risks of LBW and IUGR were found in pregnant individuals with both HDP and hypercholanemia compared with those with normotensive pregnancies with sTBA concentrations less than 4.08 μg/mL (LBW: aOR, 9.13; 95% CI, 6.88-12.12; IUGR: aOR, 19.14; 95% CI, 12.09-30.28).

CONCLUSIONS AND RELEVANCE

This study found that gestational hypercholanemia was associated with an increased risk of LBW and IUGR, especially in pregnant individuals with HDP. Therefore, it would be meaningful to monitor sTBA concentration during the follow-up of pregnancies with potential IUGR.

New Frontiers in Placenta Tissue Imaging

The placenta is a highly vascularized organ with unique structural and metabolic complexities. As the primary conduit of fetal support, the placenta mediates transport of oxygen, nutrients, and waste between maternal and fetal blood. Thus, normal placenta anatomy and physiology is absolutely required for maintenance of maternal and fetal health during pregnancy. Moreover, impaired placental health can negatively impact offspring growth trajectories as well as increase the risk of maternal cardiovascular disease later in life. Despite these crucial roles for the placenta, placental disorders, such as preeclampsia, intrauterine growth restriction (IUGR), and preterm birth, remain incompletely understood. Effective noninvasive imaging and image analysis are needed to advance the obstetrician's clinical reasoning toolkit and improve the utility of the placenta in interpreting maternal and fetal health trajectories. Current paradigms in placental imaging and image analysis aim to improve the traditional imaging techniques that may be time-consuming, costly, or invasive. In concert with conventional clinical approaches such as ultrasound (US), advanced imaging modalities can provide insightful information on the structure of placental tissues. Herein we discuss such imaging modalities, their specific applications in structural, vascular, and metabolic analysis of placental health, and emerging frontiers in image analysis research in both preclinical and clinical contexts.

Correlation of Placental Magnetic Resonance Imaging With Histopathologic Diagnosis: Detection of Aberrations in Structure and Water Diffusivity

OBJECTIVE

Noninvasive methods to identify placental pathologic conditions are being sought in order to recognize these conditions at an earlier stage leading to improved clinical interventions and perinatal outcomes. The objective of this study was to examine fixed tissue slices of placenta by T₂- and diffusion-weighted magnetic resonance imaging (MRI) and correlate the images with placental pathologic findings defined by routine gross and histologic examination.

METHODS

Four formalin-fixed placentas with significant placental pathology (maternal vascular malperfusion, chronic villitis of unknown etiology, and massive perivillous fibrin deposition) and 2 histologically normal placentas were evaluated by high-resolution MRI. Representative placental slices were selected (2 cm long and 10 mm wide) and rehydrated. Imaging was performed on a Bruker Avance 14.1 T microimager. Diffusion-weighted images were acquired from 16 slices using slice thickness 0.5 mm and in-plane resolution approximately 100 µm × 100 µm. T₂ maps were obtained from the same slices. T₂ relaxation time and apparent diffusion coefficient (ADC) were acquired from representative regions of interest and compared between normal and diseased placentas.

RESULTS

In T₂- and diffusion-weighted images, the placental microstructure differed subjectively between diseased and normal placentas. Furthermore, diseased placentas showed statistically significantly longer mean T₂ relaxation times and generally higher mean ADC.

CONCLUSION

Diffusion- and T₂-weighted MRI can potentially be used to detect significant placental pathology by using T₂ relaxation time and ADC as markers of altered placental microstructure.

Metabolomic identification of placental alterations in fetal growth restriction

Introduction: Fetal growth restriction (FGR), viz., birth weight <10th percentile is a common pregnancy complication which increases the risk of adverse fetal and newborn outcomes. The placenta is the key organ for fetal growth as it controls oxygen and nutrient availability. This study aims to elucidate the mechanisms of and identify putative placental biomarkers for FGR using high-resolution metabolomics.Methods: Placenta samples from 19 FGR cases and 30 controls were analyzed using proton magnetic resonance (¹H NMR) spectroscopy and direct flow injection mass spectrometry with reverse-phase liquid-chromatography mass spectrometry (DI-LC-MS/MS). Significant concentration differences (p-value <.05) in 179 of the 220 metabolites were measured.Results: Of the 179 metabolites, 176 (98.3%) had reduced placental levels in FGR cases. The best performing metabolite model: 3-hydroxybutyrate, glycine and PCaaC42:0 achieved an AUC (95% CI) = 0.912 (0.814-1.000) with a sensitivity of 86.7% and specificity of 84.2% for FGR detection. Metabolite set enrichment analysis (MSEA) revealed significant (p < .05) perturbation of multiple placental metabolite pathways including urea metabolism, ammonia recycling, porphyrin metabolism, bile acid biosynthesis, galactose metabolism and perturbed protein biosynthesis.Conclusion: The placental metabolic pathway analysis revealed abnormalities that are consistent with fetal hepatic dysfunction in FGR. Near global reduction of metabolite concentrations was found in the placenta from FGR cases and metabolites demonstrated excellent diagnostic accuracy for FGR detection.

Placental MRI and its application to fetal intervention

OBJECTIVE

Magnetic resonance imaging (MRI) of placental invasion has been part of clinical practice for many years. The possibility of being better able to assess placental vascularization and function using MRI has multiple potential applications. This review summarises up-to-date research on placental function using different MRI modalities.

METHOD

We discuss how combinations of these MRI techniques have much to contribute to fetal conditions amenable for therapy such as singletons at high risk for fetal growth restriction (FGR) and monochorionic twin pregnancies for planning surgery and counselling for selective growth restriction and transfusion conditions.

RESULTS

The whole placenta can easily be visualized on MRI, with a clear boundary against the amniotic fluid, and a less clear placental-uterine boundary. Contrasts such as diffusion weighted imaging, relaxometry, blood oxygenation level dependent MRI and flow and metabolite measurement by dynamic contrast enhanced MRI, arterial spin labeling, or spectroscopic techniques are contributing to our wider understanding of placental function.

CONCLUSION

The future of placental MRI is exciting, with the increasing availability of multiple contrasts and new models that will boost the capability of MRI to measure oxygen saturation and placental exchange, enabling examination of placental function in complicated pregnancies.

Fetal MRI for dummies: what the fetal medicine specialist should know about acquisitions and sequences

Fetal MRI is an increasingly used tool in the field of prenatal diagnosis. While US remains the first line screening tool, as an adjuvant imaging tool, MRI has been proven to increase diagnostic accuracy and change patient counseling. Further, there are instances when US may not be sufficient for diagnosis. As a multidisciplinary field, it is important that every person involved in the referral, diagnosis, counseling and treatment of the patients is familiar with the basic principles, indications and findings of fetal MRI. The purpose of the current paper is to equip radiologists and non-radiologists with basic MRI principles and essential topics in patient preparation and provide illustrative examples of when fetal MRI may be used. This aims to aid the referring clinician in better selecting and improve patient counseling prior to arrival in the radiology department and, ultimately, patient care.

Multi‑organ assessment via a 9.4‑Tesla MRS evaluation of metabolites during the embryonic development of cleft palate induced by dexamethasone

The aim of the present study was to determine the association between maternal metabolism and development of the fetal palate, and to suggest a potential non‑invasive prenatal diagnostic method for fetal cleft palate (CP). Dexamethasone (DXM) was used to create a CP mouse model. A 9.4‑Tesla (T) magnetic resonance spectroscopy (MRS) imager was used to measure an array of metabolites in the maternal serum, placental tissue, amniotic fluid and fetal palates. Multivariate statistical analysis was performed using SIMCA‑P 14.1 software. Following DXM treatment, variations were detected in multiple metabolites in the female mice and their fetuses based on 9.4T MRS. It was indicated that in the experimental group during CP formation, leucine, valine, creatine, acetate and citrate levels in the palatal tissue were lower, whereas lactate, alanine, proline/inositol and glutamate‑containing metabolite levels were higher, compared with the levels in the control group. In placental tissue and amniotic fluid, succinate and choline levels were lower in the experimental group. The relative concentrations of cholesterol and lipids in palatal tissues from mice treated with DXM were higher compared with the concentrations in tissues from mice in the control group, with the exception of (CH2)n lipids. In the placental tissue, the alteration in cholesterol level exhibited the opposite trend. Lipid levels for the different lipid forms varied and most of them were unsaturated lipids.

The use of magnetic resonance imaging in the prediction of birthweight

Extremes of fetal growth can increase adverse pregnancy outcomes, and this is equally applicable to single and multiple gestations. Traditionally, these cases have been identified using simple two-dimensional ultrasound which is quite limited by its low precision. Magnetic resonance imaging (MRI) has now been used for many years in obstetrics, mainly as an adjunct to ultrasound for congenital abnormalities and increasingly as part of the post-mortem examination. However, MRI can also be used to accurately assess fetal weight as first demonstrated by Baker et al in 1994, using body volumes rather than standard biometric measurements. This publication was followed by several others, all of which confirmed the superiority of MRI; however, despite this initial promise, the technique has never been successfully integrated into clinical practice. In this review, we provide an overview of the literature, detail the various techniques and formulas currently available, discuss the applicability to specific high-risk groups and present our vision for the future of MRI within clinical obstetrics.

Apparent Diffusion Coefficient of the Placenta and Fetal Organs in Intrauterine Growth Restriction

PURPOSE

This study aimed to assess apparent diffusion coefficient (ADC) of the placenta and fetal organs in intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

A prospective study of 30 consecutive pregnant women (aged 21-38 years with mean age of 31.5 years and a mean gestational week of 35 ± 2.3) with IUGR and 15 age-matched pregnant women was conducted. All patients and controls underwent diffusion-weighted magnetic resonance imaging. The ADCs of the placenta and fetal brain, kidney, and lung were calculated and correlated with neonates needing intensive care unit (ICU) admission.

RESULTS

There was a significant difference in ADC of the placenta and fetal brain, lung, and kidney (P = 0.001, 0.001, 0.04, and 0.04, respectively) between the patients and the controls. The cutoff ADCs of the placenta and fetal brain, lung, and kidney used to detect IUGR were 1.45, 1.15, 1.80, and 1.40 × 10 mm/s, respectively, with areas under the curve (AUCs) of 0.865, 0.858, 0.812, and 0.650, respectively, and accuracy values of 75%, 72.5%, 72.5%, and 70%, respectively. Combined ADC of the placenta and fetal organs used to detect IUGR revealed an AUC of 1.00 and an accuracy of 100%. There was a significant difference in ADC of the placenta and fetal brain, lung, and kidney between neonates needing admission and those not needing ICU admission (P = 0.001, 0.001, 0.002, and 0.002, respectively). The cutoff ADCs of the placenta and fetal brain, lung, and kidney used to define neonates needing ICU were 1.35, 1.25, 1.95, and 1.15 × 10 mm/s with AUCs of 0.955, 0.880, 0.884, and 0.793, respectively, and accuracy values of 86.7%, 46.7%, 76.7%, and 70%, respectively. Combined placental and fetal brain ADC used to define neonates needing ICU revealed an AUC of 0.968 and an accuracy of 93.3%.

CONCLUSION

Combined ADC of the placenta and fetal organs can detect IUGR, and combined ADC of the placenta and fetal brain can define fetuses needing ICU.

Combined diffusion-relaxometry MRI to identify dysfunction in the human placenta

Purpose

A combined diffusion‐relaxometry MR acquisition and analysis pipeline for in vivo human placenta, which allows for exploration of coupling between T2* and apparent diffusion coefficient (ADC) measurements in a sub 10‐minute scan time.

Methods

We present a novel acquisition combining a diffusion prepared spin echo with subsequent gradient echoes. The placentas of 17 pregnant women were scanned in vivo, including both healthy controls and participants with various pregnancy complications. We estimate the joint T2*‐ADC spectra using an inverse Laplace transform.

Results

T2*‐ADC spectra demonstrate clear quantitative separation between normal and dysfunctional placentas.

Conclusions

Combined T2*‐diffusivity MRI is promising for assessing fetal and maternal health during pregnancy. The T2*‐ADC spectrum potentially provides additional information on tissue microstructure, compared to measuring these two contrasts separately. The presented method is immediately applicable to the study of other organs.