Automated Visualization and Quantification of Spiral Artery Blood Flow Entering the First-Trimester Placenta, Using 3-D Power Doppler Ultrasound

3D Single Vessel Fractional Moving Blood Volume (3D-svFMBV): Fully Automated Tissue Perfusion Estimation Using Ultrasound

Power Doppler ultrasound (PD-US) is the ideal modality to assess tissue perfusion as it is cheap, patient-friendly and does not require ionizing radiation. However, meaningful inter-patient comparison only occurs if differences in tissue-attenuation are corrected for. This can be done by standardizing the PD-US signal to a blood vessel assumed to have 100% vascularity. The original method to do this is called fractional moving blood volume (FMBV). We describe a novel, fully-automated method combining image processing, numerical modelling, and deep learning to estimate three-dimensional single vessel fractional moving blood volume (3D-svFMBV). We map the PD signals to a characteristic intensity profile within a single large vessel to define the standardization value at the high shear vessel margins. This removes the need for mathematical correction for background signal which can introduce error. The 3D-svFMBV was first tested on synthetic images generated using the characteristics of uterine artery and physiological ultrasound noise levels, demonstrating prediction of standardization value close to the theoretical ideal. Clinical utility was explored using 143 first-trimester placental ultrasound volumes. More biologically plausible perfusion estimates were obtained, showing improved prediction of pre-eclampsia compared with those generated with the semi-automated original 3D-FMBV technique. The proposed 3D-svFMBV method overcomes the limitations of the original technique to provide accurate and robust placental perfusion estimation. This not only has the potential to provide an early pregnancy screening tool but may also be used to assess perfusion of different organs and tumors.

First-trimester 3D power Doppler imaging markers of utero-placental vascular development are associated with placental weight and diameter at birth: The Rotterdam Periconception Cohort

INTRODUCTION

Early utero-placental vascular development impacts placental development and function throughout pregnancy. We investigated whether impaired first-trimester utero-placental vascular development is associated with pathologic features of the postpartum placenta.

METHODS

In this prospective observational study of 65 ongoing pregnancies, we obtained three-dimensional power Doppler ultrasounds of the placenta at 7, 9 and 11 weeks of gestation. We applied VOCAL software to measure placental volume (PV), virtual reality based segmentation to measure utero-placental vascular volume (uPVV) and applied a skeletonization algorithm to generate the utero-placental vascular skeleton (uPVS). Vascular morphology was quantified by assigning a morphologic characteristic to each voxel in the uPVS (i.e. end-, bifurcation-, crossing- or vessel point). Following delivery, placentas were measured and histologically examined according to the Amsterdam criteria to assess maternal vascular malperfusion (MVM). We used linear mixed models to estimate trajectories of PV, uPVV and uPVS development. Multivariable linear regression analysis with adjustments for confounders was used to evaluate associations between PV, uPVV and uPVS development and features of the postpartum placenta.

RESULTS

We observed no associations between first-trimester PV development and measurements of the postpartum placenta. Increased first-trimester utero-placental vascular development, reflected by uPVV (β = 0.25 [0.01; 0.48]), uPVS end points (β = 0.25 [0.01; 0.48]), bifurcation points (β = 0.22 [0.05; 0.37]), crossing points (β = 0.29 [0.07; 0.52]) and vessel points (β = 0.09 [0.02; 0.17]) was positively associated with the postpartum placental diameter. uPVV was positively associated with postpartum placental weight. No associations were found with MVM.

DISCUSSION

Development of the first-trimester utero-placental vasculature is associated with postpartum placental size, whereas placental tissue development contributes to a lesser extent.

RGD-Based Fluorescence to Assess Placental Angiogenesis

Normal fetal growth and placental development depend on active angiogenesis occurring at the fetomaternal interface throughout pregnancy. Nevertheless, reliable in vivo methods to assess placental angiogenesis are still missing. Here, we describe a quantitative and noninvasive in vivo method to specifically measure placental neovascularization in the gravid mouse. This method uses a technique based on the measurement of a fluorescent molecule Angiostamp700 that targets the alpha v beta 3 (αvβ3) integrin, a protein that is highly expressed by endothelial cells during the neovascularization and by trophoblast cells during invasion of the maternal decidua. Due to this noninvasive method, quantification of the fetomaternal angiogenic activity and information regarding the outcome of pregnancy are now possible.

The human placenta project: Funded studies, imaging technologies, and future directions

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.

Synergistic regulation of uterine radial artery adaptation to pregnancy by paracrine and hemodynamic factors

Fetal growth throughout pregnancy relies on delivery of an increasing volume of maternal blood to the placenta. To facilitate this, the uterine vascular network adapts structurally and functionally, resulting in wider blood vessels with decreased flow-mediated reactivity. Impaired remodeling of the rate-limiting uterine radial arteries has been associated with fetal growth restriction. However, the mechanisms underlying normal or pathological radial artery remodeling are poorly understood. Here, we used pressure myography to determine the roles of hemodynamic (resistance, flow rate, shear stress) and paracrine [β-estradiol, progesterone, placental growth factor (PlGF), vascular endothelial growth factor] factors on rat radial artery reactivity. We show that β-estradiol, progesterone, and PlGF attenuate flow-mediated constriction of radial arteries from nonpregnant rats, allowing them to withstand higher flow rates in a similar manner to pregnant vessels. This effect was partly mediated by nitric oxide (NO) production. To better understand how the combination of paracrine factors and shear stress may impact human radial artery remodeling in the first half of gestation, computational models of uterine hemodynamics, incorporating physiological parameters for trophoblast plugging and spiral artery remodeling, were used to predict shear stress in the upstream radial arteries across the first half of pregnancy. Human microvascular endothelial cells subjected to these predicted shear stresses demonstrated higher NO production when paracrine factors were added. This suggests that synergistic effects of paracrine and hemodynamic factors induce uterine vascular remodeling and that alterations in this balance could impair radial artery adaptation, limiting blood flow to the placenta and negatively impacting fetal growth.NEW & NOTEWORTHY Placenta-specific paracrine factors β-estradiol, progesterone, and placental growth factor attenuate flow-mediated constriction of the rate-limiting uterine radial arteries, enabling higher flow rates in pregnancy. These paracrine factors induce their actions in part via nitric oxide mediated mechanisms. A synergistic combination of paracrine factors and shear stress is likely necessary to produce sufficient levels of nitric oxide during early human pregnancy to trigger adequate uterine vascular adaptation.

Imaging of placental circulations by 4D sonography with high-definition flow and spatiotemporal image correlation technology

Conventionally, two- and three- dimensional color Doppler ultrasonography are used to examine the placental vascularization, but there are limitations in the examinations. In this report, spatiotemporal image correlation (STIC) volume acquisition in high-definition flow, displayed in glass-body mode was used to study the placental vascularization in eight pregnancies. At 20 weeks' gestation, STIC technique allowed visualization of blood flow in the intraplacental branches of the umbilical artery (IPB) and the spiral artery jets in a cardiac cycle. In particular, blood flow from a mega jet penetrating more than half of the placental thickness was demonstrated. Small blood flow from a tertiary order branch of the IPB traversing the placenta and sharply diminishing into the uterine wall was also demonstrated. There were differences in the IPB pattern between normal pregnancies and pregnancies at risk of fetal growth restriction/pre-eclampsia. There were also differences in the appearance of IPB between 20- and 33-weeks' gestation. The results of this report support that it is feasible to use STIC technology to study the placental vascularization. This novel application of STIC technology can increase the understanding of the complex vascularization.

Assessment of first-trimester utero-placental vascular morphology by 3D power Doppler ultrasound image analysis using a skeletonization algorithm: the Rotterdam Periconception Cohort

STUDY QUESTION

Can three-dimensional (3D) Power Doppler (PD) ultrasound and a skeletonization algorithm be used to assess first-trimester development of the utero-placental vascular morphology?

SUMMARY ANSWER

The application of 3D PD ultrasonography and a skeletonization algorithm facilitates morphologic assessment of utero-placental vascular development in the first trimester and reveals less advanced vascular morphologic development in pregnancies with placenta-related complications than in pregnancies without placenta-related complications.

WHAT IS KNOWN ALREADY

Suboptimal development of the utero-placental vasculature is one of the main contributors to the periconceptional origin of placenta-related complications. The nature and attribution of aberrant vascular structure and branching patterns remain unclear, as validated markers monitoring first-trimester utero-placental vascular morphologic development are lacking.

STUDY DESIGN, SIZE, DURATION

In this prospective observational cohort, 214 ongoing pregnancies were included before 10 weeks gestational age (GA) at a tertiary hospital between January 2017 and July 2018, as a subcohort of the ongoing Rotterdam Periconception Cohort study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

By combining 3D PD ultrasonography and virtual reality, utero-placental vascular volume (uPVV) measurements were obtained at 7, 9 and 11 weeks GA. A skeletonization algorithm was applied to the uPVV measurements to generate the utero-placental vascular skeleton (uPVS), a network-like structure containing morphologic characteristics of the vasculature. Quantification of vascular morphology was performed by assigning a morphologic characteristic to each voxel in the uPVS (end-, vessel-, bifurcation- or crossing-point) and calculating total vascular network length. A Mann–Whitney U test was performed to investigate differences in morphologic development of the first-trimester utero-placental vasculature between pregnancies with and without placenta-related complications. Linear mixed models were used to estimate trajectories of the morphologic characteristics in the first trimester.

MAIN RESULTS AND THE ROLE OF CHANCE

All morphologic characteristics of the utero-placental vasculature increased significantly in the first trimester (P < 0.005). In pregnancies with placenta-related complications (n = 54), utero-placental vascular branching was significantly less advanced at 9 weeks GA (vessel points P = 0.040, bifurcation points P = 0.050, crossing points P = 0.020, total network length P = 0.023). Morphologic growth trajectories remained similar after adjustment for parity, conception mode, foetal sex and occurrence of placenta-related complications.

LIMITATIONS, REASONS FOR CAUTION

The tertiary setting of this prospective observational study provides high internal, but possibly limited external, validity. Extrapolation of the study’s findings should therefore be addressed with caution.

WIDER IMPLICATIONS OF THE FINDINGS

The uPVS enables assessment of morphologic development of the first-trimester utero-placental vasculature. Further investigation of this innovative methodology needs to determine its added value for the assessment of (patho-) physiological utero-placental vascular development.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by the Department of Obstetrics and Gynecology of the Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

Registered at the Dutch Trial Register (NTR6854).

Doppler evaluation of normal and abnormal placenta

Doppler techniques are needed for the evaluation of the intraplacental circulation and can be of great value in the diagnosis of placental anomalies. Highly sensitive Doppler techniques can differentiate between the maternal (spiral arteries) and fetal (intraplacental branches of the umbilical artery) components of the placental circulation and assist in the evaluation of the placental functional units. A reduced number of placental functional units can be associated with obstetric complications, such as fetal growth restriction. Doppler techniques can also provide information on decidual vessels and blood movement. Abnormal decidual circulation increases the risk of placenta accreta. Doppler evaluation of the placenta greatly contributes to the diagnosis and clinical management of placenta accreta, vasa previa, placental infarcts, placental infarction hematoma, maternal floor infarction, massive perivillous fibrin deposition and placental tumors. However, it has a limited role in the diagnosis and clinical management of placental abruption, placental hematomas, placental mesenchymal dysplasia and mapping of placental anastomoses in monochorionic twin pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Transvaginal Color Mapping Ultrasound in the First Trimester Predicts Placenta Accreta Spectrum: A Retrospective Cohort Study

OBJECTIVES

Ultrasound (US) prediction of placenta accreta spectrum (PAS) in the first trimester may be aided by postprocessing mechanisms employing color pixel quantification near the bladder-uterine serosal interface. Our objective was to create a postprocessing algorithm of color images to identify findings associated with PAS and compare quantification to sonologist impression in prospectively obtained cine US images.

METHODS

Transverse transvaginal (TV) US color cines obtained in the first trimester as part of a prospective study were reviewed. Investigators blinded to clinical outcomes reviewed anonymized cines that were archived and labeled the bladder-uterine serosal interface. Color pixels within 2 cm of the defined bladder-uterine serosal interface were ascertained using a Python-based plugin in the Horos open-source DICOM viewer. A sonologist classified the findings as suspicious for invasion, indeterminate, or normal. Statistical analysis was performed using Wilcoxon rank-sum test, Cochran-Armitage trend test, and calculation of receiver-operating characteristic (ROC) curves.

RESULTS

Fifty-four studies met inclusion criteria. Of those, six (11%) required hysterectomy with pathologic confirmation of PAS. Women requiring hysterectomy had a significantly higher color Doppler pixel area than those not requiring hysterectomy (P = .0205). A significant trend was identified in the sonologist impression of invasion (P = .0003). ROC's comparing sonologist impression to Doppler color imaging areas were comparable (P = .054).

CONCLUSIONS

Color Doppler mapping in the first trimester showed an increase in color pixel area near the bladder-uterine serosal interface in women requiring cesarean hysterectomy with histologically confirmed PAS at time of delivery, compared to women without hysterectomy or pathologic evidence of PAS.

New insights into human functional ultrasound imaging

Ultrasound imaging is a vital tool for exploring in vivo the placental function which is essential to understand pathological phenomena such as preeclampsia or intrauterine growth restriction. As technology advances including ready availability of three-dimensional (3D) probes and novel software, new markers of placental function become possible. The objective of this review was to provide an overview of the new ultrasound markers of placental function with a focus on the potential clinical application of three-dimensional power Doppler (3DPD). A broad-free text literature search was undertaken based on human placental studies and sixty full-text studies were included in this review. Three-dimensional power Doppler is a promising technique to predict preeclampsia in the first trimester. However, the influence of external factors such as body mass index, parameter standardisation and machine settings still need to be addressed. Contrast-enhanced ultrasound is currently reserved for research, because the required injected contrast mediums are not currently approved for use in pregnancy, although the safety data is reassuring.

A 10-Year Retrospective Review of Prenatal Applications, Current Challenges and Future Prospects of Three-Dimensional Sonoangiography

Realistic reconstruction of angioarchitecture within the morphological landmark with three-dimensional sonoangiography (three-dimensional power Doppler; 3D PD) may augment standard prenatal ultrasound and Doppler assessments. This study aimed to (a) present a technical overview, (b) determine additional advantages, (c) identify current challenges, and (d) predict trajectories of 3D PD for prenatal assessments. PubMed and Scopus databases for the last decade were searched. Although 307 publications addressed our objectives, their heterogeneity was too broad for statistical analyses. Important findings are therefore presented in descriptive format and supplemented with the authors’ 3D PD images. Acquisition, analysis, and display techniques need to be personalized to improve the quality of flow-volume data. While 3D PD indices of the first-trimester placenta may improve the prediction of preeclampsia, research is needed to standardize the measurement protocol. In highly experienced hands, the unique 3D PD findings improve the diagnostic accuracy of placenta accreta spectrum. A lack of quality assurance is the central challenge to incorporating 3D PD in prenatal care. Machine learning may broaden clinical translations of prenatal 3D PD. Due to its operator dependency, 3D PD has low reproducibility. Until standardization and quality assurance protocols are established, its use as a stand-alone clinical or research tool cannot be recommended.

Something old, something new: digital quantification of uterine vascular remodelling and trophoblast plugging in historical collections provides new insight into adaptation of the utero-placental circulation

STUDY QUESTION

What is the physiological extent of vascular remodelling in and trophoblast plugging of the uterine circulation across the first half of pregnancy?

SUMMARY ANSWER

All levels of the uterine vascular tree (arcuate, radial and spiral arteries (SAs)) dilate ∼2.6- to 4.3-fold between 6 and 20 weeks of gestation, with significant aggregates of trophoblasts persisting in the decidual and myometrial parts of SAs beyond the first trimester.

WHAT IS KNOWN ALREADY

In early pregnancy, endovascular trophoblasts form 'plugs' in the SAs, transiently inhibiting blood flow to the placenta, whilst concurrently the uterine vasculature undergoes significant adaption to facilitate increased blood delivery to the placenta later in gestation. These processes are impaired in pregnancy disorders, but quantitative understanding of the anatomical changes even in normal pregnancy is poor.

STUDY DESIGN, SIZE, DURATION

Serial sections of normal placentae in situ (n = 22) of 6.1-20.5 weeks of gestation from the Boyd collection and Dixon collection (University of Cambridge, UK) were digitalized using a slide scanner or Axio Imager.A1 microscope.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Spiral (n = 45), radial (n = 40) and arcuate (n = 39) arteries were manually segmented. Using custom-written scripts for Matlab® software, artery dimensions (Feret diameters; major axes; luminal/wall area) and endovascular trophoblast plug/aggregate (n = 24) porosities were calculated. Diameters of junctional zone SAs within the myometrium (n = 35) were acquired separately using a micrometre and light microscope. Decidual thickness and trophoblast plug depth was measured using ImageJ.

MAIN RESULTS AND THE ROLE OF CHANCE

By all measures, radial and arcuate artery dimensions progressively increased from 6.1 to 20.5 weeks (P < 0.01). The greatest increase in SA calibre occurred after 12 weeks of gestation. Trophoblast aggregates were found to persist within decidual and myometrial parts of SA lumens beyond the first trimester, and up to 18.5 weeks of gestation, although those present in the second trimester did not appear to prevent the passage of red blood cells to the intervillous space. Trophoblasts forming these aggregates became more compact (decreased in porosity) over gestation, whilst channel size between cells increased (P = 0.01). Decidual thickness decreased linearly over gestation (P = 0.0003), meaning plugs occupied an increasing proportion of the decidua (P = 0.02).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Although serial sections were assessed, two-dimensional images cannot completely reflect the three-dimensional properties and connectivity of vessels and plugs/aggregates. Immersion-fixation of the specimens means that vessel size may be under-estimated.

WIDER IMPLICATIONS OF THE FINDINGS

Uterine vascular remodelling and trophoblast plug dispersion is a progressive phenomenon that is not completed by the end of the first trimester. Our quantitative findings support the concept that radial arteries present a major site of resistance until mid-gestation. Their dimensional increase at 10-12 weeks of gestation may explain the rapid increase in blood flow to the placenta observed by others at ∼13 weeks. Measured properties of trophoblast plugs suggest that they will impact on the resistance, shear stress and nature of blood flow within the utero-placental vasculature until mid-gestation. The presence of channels within plugs will likely lead to high velocity flow streams and thus increase shear stress experienced by the trophoblasts forming the aggregates. Quantitative understanding of utero-placental vascular adaptation gained here will improve in silico modelling of utero-placental haemodynamics and provide new insights into pregnancy disorders, such as fetal growth restriction.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by a Royal Society Te Aparangi Marsden Grant [18-UOA-135]. A.R.C. is supported by a Rutherford Discovery Fellowship [14-UOA-019]. The authors have no conflict of interest to declare.

Study of the Development of Placental Microvascularity by Doppler SMI (Superb Microvascular Imaging): A Reality Today

Our objective was to evaluate the development of placental vascularization in normal gestation by using Doppler superb microvascular imaging (SMI). The fetal and maternal parameters of 20 pregnant women without pathology were evaluated at weeks 12, 16, 20-22, 24-26, 28-30, 32-34, 36-38 and 40-42. Doppler SMI was used to evaluate the placental vascularization (pulsatile index and peak systolic velocity) of the primary, secondary and tertiary (third) villi, and qualitative placental descriptions and anatomic-pathologic studies of these placentas were performed. The number of cotyledons identified by Doppler SMI increased from two between weeks 16 and 18 to 24 between weeks 28 and 38. The secondary and tertiary villi began developing at 20 wk of gestation. The pulsatile index of the primary villi remained constant (0.8-0.9 in all pregnancies). The pulsatile index of the secondary and tertiary villi increased from 1.1 to 1.53 and from 1.4 to 1.68, respectively. The peak systolic velocity underwent a significant increase throughout gestation in the secondary and tertiary villi (9.2 to 34.9 cm/s and 7.5 to 52.9 cm/s, respectively). We evaluated the development of placental microvascularization using Doppler SMI in pregnancies without pathology and describe normal placental Doppler SMI findings.

Contrast-enhanced ultrasound for the assessment of placental development and function

The use of contrast agents as signal enhancers during ultrasound improves visualization and the diagnostic utility of this technology in medical imaging. Although widely used in many disciplines, contrast ultrasound is not routinely implemented in obstetrics, largely due to safety concerns of administered agents for pregnant women and the limited number of studies that address this issue. Here the microbubble characteristics that make them beneficial for enhancement of the blood pool and the quantification of real-time imaging are reviewed. Literature from pregnant animal model studies and safety assessments are detailed, and the potential for contrast-enhanced ultrasound to provide clinically relevant data and benefit our understanding of early placental development and detection of placental dysfunction is discussed.

Advances in imaging feto-placental vasculature: new tools to elucidate the early life origins of health and disease

Optimal placental function is critical for fetal development, and therefore a crucial consideration for understanding the developmental origins of health and disease (DOHaD). The structure of the fetal side of the placental vasculature is an important determinant of fetal growth and cardiovascular development. There are several imaging modalities for assessing feto-placental structure including stereology, electron microscopy, confocal microscopy, micro-computed tomography, light-sheet microscopy, ultrasonography and magnetic resonance imaging. In this review, we present current methodologies for imaging feto-placental vasculature morphology ex vivo and in vivo in human and experimental models, their advantages and limitations and how these provide insight into placental function and fetal outcomes. These imaging approaches add important perspective to our understanding of placental biology and have potential to be new tools to elucidate a deeper understanding of DOHaD.

Computational modeling of the interactions between the maternal and fetal circulations in human pregnancy

In pregnancy, fetal growth is supported by its placenta. In turn, the placenta is nourished by maternal blood, delivered from the uterus, in which the vasculature is dramatically transformed to deliver this blood an ever increasing volume throughout gestation. A healthy pregnancy is thus dependent on the development of both the placental and maternal circulations, but also the interface where these physically separate circulations come in close proximity to exchange gases and nutrients between mum and baby. As the system continually evolves during pregnancy, our understanding of normal vascular anatomy, and how this impacts placental exchange function is limited. Understanding this is key to improve our ability to understand, predict, and detect pregnancy pathologies, but presents a number of challenges, due to the inaccessibility of the pregnant uterus to invasive measurements, and limitations in the resolution of imaging modalities safe for use in pregnancy. Computational approaches provide an opportunity to gain new insights into normal and abnormal pregnancy, by connecting observed anatomical changes from high-resolution imaging to function, and providing metrics that can be observed by routine clinical ultrasound. Such advanced modeling brings with it challenges to scale detailed anatomical models to reflect organ level function. This suggests pathways for future research to provide models that provide both physiological insights into pregnancy health, but also are simple enough to guide clinical focus. We the review evolution of computational approaches to understanding the physiology and pathophysiology of pregnancy in the uterus, placenta, and beyond focusing on both opportunities and challenges. This article is categorized under: Reproductive System Diseases >Computational Models.

Uric Acid Values Along with Doppler Sonography Findings as a Tool for Preeclampsia Screening

Introduction

Preeclampsia is defined as hypertension (systolic pressure ≥140 mmHg or diastolic pressure ≥90 mmHg) after week 20 of gestation with one or more of the following symptoms: proteinuria, organ dysfunction (including renal, hepatologic, hematologic or neurological complications) and in case of stagnation of fetal development. So far, there are no valid clinical tools or tests that can tell with sufficient sensitivity and specificity in early pregnancy which pregnant woman will develop preeclampsia or have unwanted outcomes.

Aim

To present the properties of biochemical parameter, uric acid, in patients with signs of preclampsia, which was confirmed by Doppler sonography.

Methods

The study included 60 female subjects in the second trimester of pregnancy who were examined or were hospitalized at the Clinic of Gynecology and Obstetrics, Clinical Center University of Sarajevo. Pregnant women who had normal Doppler sonography scan of the uterine arteries in the second trimester of pregnancy were included in the control group, while pregnant women with pathologic Doppler sonographic findings in the second trimester of pregnancy were included in the group of pregnant women at risk of preeclampsia, i.e. the study group.

Results

There is statistically significant difference between the average value of uric acid in the control and in the study group (213.36 ± 28.96 μmol / L vs 249.73 ± 47.06 μmol / L) (F = 12.991; p = 0.001). Applying the Wilcoxon non-parametric paired test to the average uric acid values during all measurements within the control group, no statistically significant difference was found. There was a statistically significant increase in the study group between all measurements, from 18.04 μmol / L between the first and second measurement (Z = -1.955; p = 0.043), 29.10 μmol / L between the second and third measurement (Z = -2.973; p = 0.003), 37.27 μmol / L between the third and fourth measurement (Z = -4.325; p = 0.001) and 109.87 μmol / L at the end of the study in comparison to values from the start of the study (Z = -4.309; p = 0.001).

Conclusion

Uric acid values should become part of a broad biochemical range in screening and optimizing the treatment of patients diagnosed with early preeclampsia.

Nanoparticle Contrast-enhanced T1-Mapping Enables Estimation of Placental Fractional Blood Volume in a Pregnant Mouse Model

Non-invasive methods for estimating placental fractional blood volume (FBV) are of great interest for characterization of vascular perfusion in placentae during pregnancy to identify placental insufficiency that may be indicative of local ischemia or fetal growth restriction (FGR). Nanoparticle contrast-enhanced magnetic resonance imaging (CE-MRI) may enable direct placental FBV estimation and may provide a reliable, 3D alternative to assess maternal-side placental perfusion. In this pre-clinical study, we investigated if placental FBV at 14, 16, and 18 days of gestation could be estimated through contrast-enhanced MRI using a long circulating blood-pool liposomal gadolinium contrast agent that does not penetrate the placental barrier. Placental FBV estimates of 0.47 ± 0.06 (E14.5), 0.50 ± 0.04 (E16.5), and 0.52 ± 0.04 (E18.5) were found through fitting pre-contrast and post-contrast T1 values in placental tissue using a variable flip angle method. MRI-derived placental FBV was validated against nanoparticle contrast-enhanced computed tomography (CE-CT) derived placental FBV, where signal is directly proportional to the concentration of iodine contrast agent. The results demonstrate successful estimation of the placental FBV, with values statistically indistinguishable from the CT derived values.