Placental Elasticity Research Articles

80: Longitudinal assessment of placental shear-wave elastography and correlation with placental circulation in normal pregnancies

Evidence suggests an increase in placental elasticity in complicated pregnancies. Shear-wave elastography (SWE) is a novel ultrasound (US)-based technology that measures tissue elasticity. To our knowledge, SWE of placental tissue has not been measured longitudinally across gestation, starting in the first trimester. Our objective was to determine changes in SWE of placental tissue and its relationship with utero-placental circulation in normal pregnancies. Normal pregnant women with singletons were consented for serial US starting between 12 0/7 and 13 6/7 wks. US were performed every 2 wks until 16 wks, then every 4 wks until delivery. Guided by SWE propagation maps, placental SWE (KPa) was measured from homogeneous circular shaped SWE-ROI obtained in a sagittal plane of the placenta at the level of the cord insertion. The average of 15 SWE was used per US. Pulsatility index of spiral (SA-PI) and fetal placental arterioles (FPA-PI) were longitudinally obtained by averaging 6 measurements per US. Women who had BMI ≥ 30 kg/m2 at enrollment or who developed any complication were excluded. Pearson's correlation tested strength of associations. RM-ANOVA and TUKEY HSD were used for analysis. 83 women were included in this study with 8 US per pregnancy. SWE showed slight, but significant increase with advancing gestation (p< 0.0001) (Figure 1). Sub-group comparisons revealed significant differences between wk 14 and 16 compared to wks 28, 32, and 36 (Table 1). SWE showed no significant correlation with PI of placental vessels (SA-PI, R -0.08; FPA-PI, R -0.2). Non-invasive assessment of placental tissue elasticity throughout gestation is feasible. In our normal cohort, placental elasticity increased, within a narrow SWE range, with advancing gestation. This increase in elasticity probably represents physiologic changes in placental tissue. This SWE nomogram can be used as a reference to assess placental tissue elasticity in complicated pregnancies.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

266: Placental elasticity imaging demonstrates feasibility of an ultrasound-based method for generation of a placental biomarker

To demonstrate the validity of elasticity imaging as a novel method of interrogating structural characteristics of human placentae. Our goal is to identify easily reproducible, direct, and non-invasive placental biomarkers based on elasticity imaging to detect and predict placenta-related disease. A prospective, descriptive cohort of unselected women presenting for obstetric care at a tertiary medical center were enrolled antenatally for post-delivery placental collection. Sheer wave speeds (SWS) of the ex vivo placenta were measured using ultrasound elasticity techniques based on Acoustic Radiation Force Impulse (ARFI) technology on a Siemens S3000 research platform. SWS data were acquired in triplicate with the placenta in a water bath at physiologic temperature over a variety of acquisition conditions (Figure 1). SWS were compiled to describe the range of measurements within and between placentae. 10 term were patients enrolled for ex vivo placental ultrasound with 1433 regions analyzed in triplicate across 4 arbitrarily assigned quadrants in 3 acquisition conditions representing a total of 4299 elastography measurements. Consistent precision and interplacental variability in SWS were demonstrated with SEM < 0.5 in >99% of all measurements across acquisition conditions. SWS were evaluated at different depths and radial circumferences with ratios between depths within the same plane also reported (Figure 2). Elasticity imaging of placental tissue demonstrates high precision with serial sampling of the same region of interest across a variety of acquisition strategies including when introducing artifacts that would be encountered in antenatal assessment. While intra-placental variability was similar in magnitude to inter-placental variability, SWS ratios calculated in a single plane can provide within-tissue correction and are dimensionless, thus representing an opportunity to standardize assessment across ultrasound platforms. Both high precision and the opportunity for standardization support the feasibility of elastography use for a placental biomarker.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Placental elasticity assessment by point shear wave elastography in pregnancies with intrauterine growth restriction

Background Placental elasticity varies in different diseases. Our objective was to evaluate placental elasticity using point shear wave elastography (pSWE) in pregnancies with intrauterine growth restriction (IUGR). Methods A total of 66 pregnant women with IUGR and 81 healthy pregnant women were enrolled. Placental elasticity was measured using the transabdominal pSWE method. Ten measurements were made, and the mean was accepted as the mean placental elasticity value in each case. The results for IUGR pregnancies and controls were compared. Results The mean pSWE values were significantly higher in pregnancies with IUGR, which means that women with IUGR have stiffer placentas (P < 0.001). Furthermore, the pSWE values were significantly and positively correlated with Doppler indices and adverse perinatal outcomes. Conclusion The pregnancies with IUGR had stiffer placentas than the healthy controls. The utilization of pSWE for placental elasticity may be useful in the diagnosis and management of IUGR as a supplement to the existing ultrasonography methods.

Does the placental strain ratio correlate with the umbilical artery Doppler values?

Objective: The aim of this study is to reveal whether there is any relationship between strain elastography (SE) values and Doppler ultrasonography (US) findings, and to investigate the availability of SE in early diagnosis of preeclampsia (PE). Material and Methods: The authors examined 21-24 week old patients who applied to this clinic for anomaly screening. Only 55 pregnant women with anterior or anterolateral placental placement were included in the study. Doppler US data and placental strain elastography values were compared statistically. Results: There was an inverse correlation between umbilical artery resistance index (RI) values and placental strain ratios. Discussion: Histopathological examination shows that, as a result of the increasing extracellular matrix proteins due to increased inflammation, elasticity in the placental tissue decreases, and this may lead to an increase in placental stiffness. Also it is known that, abnormal Doppler US findings are considered to be a weak positive predictor of placental insufficiency. Therefore the present authors compared Doppler US with placental elastography and found an inverse correlation between umbilical artery RI value and placental strain ratio. Conclusion: Placental elasticity can be used for placental abnormalities in addition to other methods, but further studies are needed to use placental elasticity as a positive predictive marker for placental insufficiency.

Placental Elasticity as a New Non-invasive Predictive Marker of Pre-eclampsia

Point shear wave elastography is an ultrasonography technique used to evaluate tissue elasticity. We examined whether placental elasticity is useful for predicting the onset of pre-eclampsia. Two hundred twenty-one participants were divided into two groups: one group at low risk (n = 185) and the other at high risk (n = 36) for pre-eclampsia. The two groups were compared with respect to shear wave velocity (SWV) of the placenta. Use of SWV as a predictor of pre-eclampsia was also investigated by creating a receiver operating characteristic (ROC) curve. The ROC curve was used to set a cutoff SWV value for predicting pre-eclampsia. The SWV of the high-risk group was significantly higher than that of the low-risk group (p < 0.001). Thirteen participants developed pre-eclampsia after SWV measurements, and the SWVs of these participants were significantly higher than those of participants in who pre-eclampsia did not develop. The cutoff value and area under the ROC curve were 1.188 m/s and 0.9118, respectively. Placental elasticity was significantly increased even before the onset of pre-eclampsia onset and, thus, may be a parameter used to predict the onset of pre-eclampsia.

Evaluation of a Healthy Pregnant Placenta with Shear Wave Elastography

Background: The placenta is a soft organ with vital importance. Increased placental stiffness was reported in pathological conditions emerging during pregnancy, such as diabetes mellitus and hypertension. Nowadays, placental stiffness can be quantitatively measured using the shear wave elastography (SWE) technique. Objectives: We aimed to assess the factors affecting elasticity by finding the normal elastogram values of healthy pregnancy placentas using the SWE technique due to the importance of early diagnosis in risky pregnancies. Patients and Methods: In total, 288 healthy pregnant women in the second or third trimester were included in our prospective study. The pregnant women who had pathology in their fetus and its appendices or a posteriorly located placenta were excluded from the study. Obstetric ultrasonography and a placental elasticity assessment were performed in all the pregnant women. Speed values were obtained from five different locations of the placenta, including the central S1, S2, S3, S4 and peripheral P regions. The elasticity of the regions were compared, and the factors affecting elasticity were investigated. Results: There were significant differences among the velocity values obtained from five different areas of the placenta. The mean velocity values obtained from the central region were higher than those of the peripheral region (P < 0.001). There was also a significant difference in the mean velocity measurements obtained from the central region (P < 0.001). The hardest region of the placenta was the maternal surface, while the softest region was the peripheral surface. The elastographic velocity values of the placenta were found to correlate with maternal age, body mass index, placental localization, thickness, and grade, whereas it did not correlate with gravidity, parity, gestational week, and amniotic fluid index . Conclusion: The elasticity of the placenta varied according to the region and surface, whereas it did not change according to gestational week. It may be convenient to use the elasticity values obtained by SWE from specified regions in the follow-up of placentas in high-risk pregnancies. However, considering the affecting factors and contradictory study results, a large number of large-scale studies is required to strengthen the efficiency of SWE in the placental assessment.

EP03.14: Shear wave elastography in measurement of placenta in gestational diabetes mellitus

To establish the normal reference range of elasticity in placenta, analysis its relationship with different gestational age and placental mature grading. To compare the difference between gestational diabetes mellitus and normal pregnancy in placental elasticity. Totally 168 normal singleton fetuses between 21and 40 gestational weeks were enrolled in this study, shear wave elastography was used to measure the placental elasticity, the mean, min and max of Young modulus were recorded. The correlation between all measurements and the gestational weeks or placental maturity grading was analysed. 20 fetuses collected randomly was examined by the same/different operator to analysed the repeatability/consistency reliability. 22 placentas of A1 gestational diabetes mellitus and 14 placentas of A2 gestational diabetes mellitus were assessed and compared with the normal. 1. In all healthy controls, placental elasticity had no relationship with gestational age and placental mature grading. 2. The repeatability/consistency reliability of the data obtained by the same /two different operator were good. 3. Young's modulus in normal placenta were 4.04±0.83 kPa (mean), 2.03±0.83 kPa (min) and 6.71±1.44 kPa (max), Young's modulus in A1 gestational diabetes mellitus placenta were 6.39±1.74 kPa (mean), 2.95±1.05 kPa(min) and 10.78±2.94 kPa (max), Young's modulus in A2 gestational diabetes mellitus placenta were 11.96±7.29 kPa (mean), 6.79±4.70 kPa (min) and 18.94±11.61 kPa (max), the interquartile range were 6.54-15.02kPa (mean), 2.58-10.97kPa (min) and 10.43-27.29kPa (max). The measurements of both A1 and A2 were higher than healthy controls (p<0.05) and the measurements of A2 were higher than those of A1 (p<0.05). Placental elasticity had no relationship with gestational age and placental mature grading; Shear wave elastography can be used to measure the elasticity of placenta in normal and gestational diabetes mellitus.

Measurement of shear wave speed dispersion in the placenta by transient elastography: A preliminary ex vivo study.

BackgroundPlacental elasticity may be modified in women with placental insufficiency. Shear wave elastography (SWE) can measure this, using acoustic radiation force, but the safety of its use in pregnant women has not yet been demonstrated. Transient elastography (TE) is a safer alternative, but has not yet been applied to the placenta. Moreover, the dispersion of shear wave speed (SWS) as a function of frequency has received relatively little study for placental tissue, although it might improve the accuracy of biomechanical assessment.ObjectiveTo explore the feasibility and reproducibility of TE for placental analysis, to compare the values of SWS and Young’s modulus (YM) from TE and SWE, and to analyze SWS dispersion as a function of frequency ex vivo in normal placentas.Materials and methodsTen normal placentas were analyzed ex vivo by an Aixplorer ultrasound system as shear waves were generated by a vibrating plate and by using an Aixplorer system.The frequency analysis provided the value of the exponent n from a fractional rheological model applied to the TE method. We calculated intra- and interobserver agreement for SWS and YM with 95% prediction intervals, created Bland-Altman plots with 95% limits of agreement, and estimated the intraclass correlation coefficient (ICC).Main resultsThe mean SWS was 1.80 m/s +/- 0.28 (standard deviation) with the TE method at 50 Hz and 1.82 m/s +/-0.13 with SWE (P = 0.912). No differences were observed between the central and peripheral regions of placentas with either TE or SWE. With TE, the intraobserver ICC for SWS was 0.68 (0.50–0.82), and the interobserver ICC for SWS 0.65 (0.37–0.85). The mean parameter n obtained from the fractional rheological model was 1.21 +/- 0.12, with variable values of n for any given SWS.ConclusionsTE is feasible and reproducible on placentas ex vivo. The frequency analysis of SWS provides additional information about placental elasticity and appears to be able to distinguish differences between placental structures.

Use of ARFI elastography in the prediction of placental invasion anomaly via a new Virtual Touch Quantification Technique

We aimed to evaluate the efficiency of placental elasticity in predicting a placental invasion anomaly with the Virtual Touch Quantification (VTQ) technique. Pregnant women in the third trimester with suspected placental invasion anomaly were enrolled into the research (n = 58). The placenta was evaluated and divided into three equal parts as foetal edge (inner 1/3 of placenta), maternal edge (outer 1/3 of placenta) and the central part (central 1/3 of placenta). Shear wave velocity (SWV) measurements were used in the elastographic evaluation of placentas by VTQ. We performed the measurements at the different regions of placenta for sampling the variety areas of the placenta. Acoustic Radiation Force Impulse (ARFI) Elastography scores were significantly higher in the group in which an invasion was detected during the surgery of patients with preoperative placental invasion suspicion. A significant difference in the measurements of the inner, central and outer third of the placenta between the groups was found (p < .001). In this study, we have shown higher SWV scores of placental measurements of the patients with preoperative suspected anomalies and an invasion detected during their surgery. These findings may reflect an event at the tissue elasticity level and we hope that the use of the VTQ technique may contribute to an early prediction of placental invasions before surgery in the future via new research.Impact statementWhat is already known on this subject? Placenta invasion anomalies (PIA’s) are characterized by haemorrhages which can threat the mother’s life. Placental invasion anomalies are among the most important causes of maternal mortality and morbidity. Early diagnosis is very important condition in reducing the mortality and morbidity. Gray scale ultrasonography (US) is mostly used in early diagnosis of PIA’s. Acoustic radiation force impulse elastography (ARFI) is a new elastographic ultrasonography technic. We aimed to evaluate a new method in the early diagnosis of PIA’s using ARFI technique. There is no study in the diagnosis of PIA’s by ARFI in the literature to our knowledge. We think that this original study will contribute to the literature.What do the results of this study add? We showed the accuracy of ARFI in determination of PIA’s. ARFI scores were significantly higher in the group in which invasion was detected during surgery of patients with preoperative placental invasion suspicion.What are the implications are of these findings for clinical practice and/or further research? Our findings may reflect an event at the tissue elasticity level and we hope that the use of VTQ technique may contribute to early predict of placental invasions before surgery in the future via new researches. Early diagnosis of placental invasion anomalies may reduce mortality and morbidity.

In vivo assessment of placental elasticity in intrauterine growth restriction by shear-wave elastography

PurposeIn this study, we evaluated the placental elasticity in vivo by shear-wave elastography in pregnant women under follow-up for intrauterine growth restriction (IUGR) and compared the elasticity values to normal pregnancies. Material and methodsThis prospective study included 42 pregnant women with a possible diagnosis of intrauterine growth restriction based on obstetrical grayscale and Doppler ultrasonography and 42 women with a normal pregnancy during the 2nd and 3rd trimester. During follow-up examinations, seven fetuses showed an increased growth and were delivered with a birth-weight above the 10 percentile. However, for statistical purposes we included these seven patients in the IUGR group due to prospective nature of the study. All patients initially underwent obstetrical grayscale and Doppler ultrasonography with measurement of resistivity and pulsatility indices from uterine arteries. Subsequently, elasticity values of the peripheral and central part of the placentas from fetal and maternal surfaces were measured by shear-wave elastography. Following delivery, Apgar scores at 1st and 5th minute, birth weight were collected. For statistical analysis, Mann-Whitney U test was used. ROC curves were plotted and cut-off values for elasticity values were analyzed. ResultsMedian elasticity values of the central part of the placentas from maternal (28kPa vs 6kPa) and fetal sides (21.5kPa vs 5kPa) were significantly higher in IUGR pregnancies compared to the control group (p<0.001). Similarly, median elasticity values of peripheral part of placentas from maternal (22kPa vs 5.35kPa) and fetal sides (22.5kPa vs 5.3kPa) were significantly higher in IUGR pregnancies compared to the control group (p<0.001). ConclusionPlacental stiffness values are significantly higher in patients with IUGR. Shear-wave elastography can be used as a non-invasive, complementary method to gray-scale and Doppler ultrasound for diagnosing IUGR.

Placental elasticity on patients with gestational diabetes: Single institution experience

BackgroundGestational diabetes is defined as glucose intolerance which is first recognized in pregnancy. Oral glucose tolerance test (OGTT) is the cornerstone in diagnosing gestational diabetes. Placental elasticity evaluation is relatively new concept and is principally used for research purposes. We aimed to find any relation between placental elasticity evaluation and patients of gestational diabetes diagnosed by 75 g OGTT. MethodsThere were 91 patients took part in study, forming two groups as gestational diabetic patients (21 patients) and control group (70 patients). Elasticity of placenta was determined by acoustic radiation force impulse technology utilized by two blinded radiology specialists. ResultsWe were not able to find any correlation between 75 g OGTT values and placental elasticity measurements (p > .05). Also placental elasticity was not found to be significantly different in two groups (p > .05). ConclusionPlacental elasticity measurement on the 24th–28th weeks does not seem to be a marker for identification of gestational diabetes.

SWAVE Imaging of Placental Elasticity and Viscosity: Proof of Concept

The placenta is the interface between the fetus and the mother and is vital for fetal development. Ultrasound elastography provides a non-invasive way to examine in vivo the stiffness of the placenta; increased stiffness has previously been linked to fetal growth restriction. This study used a previously developed dynamic elastography method, called shear wave absolute vibro-elastography, to study 61 post-delivery clinically normal placentas. The shear wave speeds in the placenta were recorded under five different low-frequency mechanical excitations. The elasticity and viscosity were estimated through rheological modeling. The shear wave speeds at excitation frequencies of 60, 80, 90, 100 and 120 Hz were measured to be 1.23 ± 0.44, 1.67 ± 0.76, 1.74 ± 0.72, 1.80 ± 0.78 and 2.25 ± 0.80 m/s. The shear wave speed values we obtained are consistent with previous studies. In addition, our multi-frequency acquisition approach enables us to provide viscosity estimates that have not been previously reported.

Acoustic radiation force impulse elastosonography of placenta in maternal red blood cell alloimmunization: a preliminary and descriptive study.

Maternal red blood cell alloimmunization is an important cause of fetal morbidity and mortality in the perinatalperiod, despite well-organized prophylaxis programs. The objective of the study was to evaluate placental elasticity by usingAcoustic Radiation Force Impulse (ARFI) in Rhesus (Rh) alloimmunized pregnant women with hydropic and nonhydropicfetuses and to compare those with healthy pregnant women. This case-control and descriptive studycomprised twenty-eight healthy pregnant women, 14 Rh alloimmunized pregnant women with nonhydropic fetuses, and 16 Rhalloimmunized pregnant women with hydropic fetuses in the third trimester of pregnancy. Placental elasticity measurementswere performed by ARFI elastosonography at the day of delivery. The maternal characteristics and neonatal outcomes of thepatients were also noted. The highest mean placental ARFI scores were observed in Rh alloimmunized pregnantwomen with hydropic fetuses (1.13 m/s) (p=0.001). Healthy controls and Rh alloimmunized pregnant women with nonhydropicfetuses had similar mean placenta ARFI scores (0.84 m/s, 0.88 m/s, respectively) (p<0.05). Based onthe present findings, the placenta becomes stiffer in Rh alloimmunized pregnancies complicated with hydrops fetalis. Theincreased placental ARFI scores may be a supplemental marker for adverse pregnancy outcomes, additional to Doppler evaluationof middle cerebral artery. This data should be confirmed with a large sample size and prospective studies by using serialmeasurements of ARFI elastosonography in maternal red blood cell alloimmunization.

Placental Elasticity and Histopathological Findings in Normal and Intra-Uterine Growth Restriction Pregnancies Assessed with Strain Elastography in Ex Vivo Placenta

The aim of this study was to investigate the differences of placental elasticity between intra-uterine growth restriction (IUGR) and normal pregnancies to show whether or not there is any association between histopathological changes and placental elasticity. Fifty-five human placentas were collected at delivery, including 25 with IUGR and 30 controls. Strain elastography (SE) was performed ex vivo and all placentas were examined histopathologically. Elasticity index (EI) and histopathological findings were compared between groups. The placental stiffness and presence of histopathological changes were higher in the IUGR group than in controls (p < 0.05). Also, histopathological findings were associated with decreased EI values, but no specific patterns of histologic abnormalities were identified except villitis and delayed villous maturity. Distinct reduced placental elasticity could be the result of the cumulative effects of all the histologic findings in IUGR.

Comparison of placental elasticity in normal and pre-eclamptic pregnant women by acoustic radiation force impulse elastosonography.

The aim of this research was to study and compare placental elasticity with acoustic radiation force impulse (ARFI) elastography in pre-eclamptic and normal pregnancies. A total of 107 singleton pregnancies in the third trimester (38 healthy control subjects, 34 patients with gestational hypertension, and 35 pre-eclampsia patients) were included in the study. ARFI elastography was used to determine the placental elasticity in the three predetermined regions of the placenta (the fetal edge, maternal edge, and central part of the placenta). The obstetrical data regarding grayscale and Doppler ultrasonography and perinatal outcomes were reviewed. A mean placental shear wave velocity cut-off value that predicts the presence of pre-eclampsia was determined. The shear wave elasticity values in the pre-eclampsia group in all three regions were significantly higher than in the gestational hypertension and healthy control groups (P=0.001). The most significant difference was found in the peripheral edge of the placenta from the fetal surface in the pre-eclampsia group (P=0.001). The stiffness of the placenta determined by the ARFI technique is significantly higher in pre-eclampsia patients. ARFI elastography of the placenta might be used as a non-invasive and easy method in the diagnosis and evaluation of pre-eclampsia as a supplement to the already existing methods.

Placental elastography in a murine intrauterine growth restriction model

To compare placental elasticity in normal versus intrauterine growth restriction (IUGR) murine pregnancies using shear wave elastography (SWE). Intrauterine growth restriction was created by ligation of the left uterine artery of Sprague-Dawley rats on E17. Ultrasonography (US) and elastography were performed 2 days later on exteriorized horns after laparotomy. Biparietal diameter (BPD) and abdominal diameter (AD) were measured and compared in each horn. Placental elasticity of each placenta was compared in the right and left horns, respectively, using the Young's modulus, which increases with increasing stiffness of the tissue. Two hundred seventeen feto-placental units from 18 rats were included. Fetuses in the left ligated horn had smaller biometric measurements than those in the right horn (6.7 vs 7.2 mm, p < 0.001, and 9.2 vs 11.2 mm, p < 0.001 for BPD and AD, respectively). Mean fetal weight was lower in the pups from the left than the right horn (1.65 vs 2.11 g; p < 0.001). Mean (SD) Young's modulus was higher for placentas from the left than the right horn (11.7 ± 1.5 kPa vs 8.01 ± 3.8 kPa, respectively; p < 0.001), indicating increased stiffness in placentas from the left than the right horn. There was an inverse relationship between fetal weight and placental elasticity (r = 0.42; p < 0.001). Shear wave elastography may be used to provide quantitative elasticity measurements of the placenta. In our model, placentas from IUGR fetuses demonstrated greater stiffness, which correlated with the degree of fetal growth restriction.

Preliminary study of acoustic radiation force impulse in the placental function of normal population and patients with severe preeclampsia

Objective To investigate the clinical value of acoustic radiation forcs impulse (ARFI) in quantitative evaluating placental elasticity. Methods The study population included 487 normal pregnant women, and ARFI generated shear wave velocity (SWV) was measured. On the basis of gestational ages, placental sites and sampling depths in region of interest (ROI), the normal population was divided into different groups.One-way analysis of variance was used to compare the discrepancy on the SWV values amomg the nomal placental sites or the sampling depths in ROI. Pearson correlation coefficient were used to assess the possible relationships between the normal placental SWV values and the different gestational ages or the placental grades. A total of 51 cases were diagnosed with severe preeclampsia, among them 25 cases were categorized as severe preeclampsia with fetal growth restriction (FGR). The placental SWV values were measured and compared with those of the normal population. The pathological examinations were performed on 50 normal and 51 abnormal placentas. Results Basing on the placental sites, the normal population were divided into three groups: anterior wall, lateral wall and posterior wall groups. Compared with the posterior wall group, the placental SWV values in the anterior wall or lateral wall group significantly decreased (P<0.05). No statistical significant difference was found between the anterior wall group and the lateral wall group. Basing on the distance from the sampling depths to the probe (range from 2 to 7.99 cm, and each additional 1 cm corresponding a group), the normal population were divided into six groups. There was statistical significant difference for the placental SWV values between the two groups of distance in the range of 2.0 to 5.99 cm and 6.0 to 7.99 cm (P<0.05). There was no statistical significant difference between the other two groups. The mean SWV value was (0.78±0.08 m/s) in the normal group. No significant relationships were found between the placental SWV values and the gestational ages of the normal population. However the placental SWV values were significantly related to the placental grades. For the placental SWV values, there was statistical significant difference between the normal group and the abnormal group (P<0.05). No statistical significant difference was found between the severe preeclampsia group and the severe preeclampsia with FGR group. The pathological examinations also showed significant changes in the abnormal group. Conclusions ARFI may quantitatively analyze the placental elasticity and make a difference between nomal and abnormal placenta. Key words: Ultrasonography, prenatal; Placenta; Severe preeclampsia; Acoustic radiation force impulse

Placental elasticity evaluation using virtual touch tissue quantification during pregnancy

IntroductionVirtual touch tissue quantification (VTTQ) has been developed to evaluate tissue elasticity. Our previous study using delivered placentas showed increased elasticity in fetal growth restriction (FGR). Therefore, we investigated changes in placental elasticity during pregnancy, including complicated pregnancies. MethodsBased on complications, 199 women were divided into 5 groups (normal, FGR, pregnancy induced hypertension (PIH), diabetes mellitus and collagen disease), and shear wave velocity (SWV) of the placenta, measured using VTTQ, was compared. A cross-sectional study was performed with the 143 normal cases to construct the reference range. The association between placental SWV and the expression ratio of collagen fibers in the placenta stained with Masson's trichrome was determined. ResultsThe SWV was safely measured for all participants. The correlation between SWV and gestational weeks was not significant. The mean ± SD SWVs in the normal, FGR, and PIH groups were 0.98 ± 0.21, 1.28 ± 0.39, and 1.60 ± 0.45 m/sec, respectively. The FGR and PIH groups had significantly higher SWVs than that of the normal group. SWV and the expression ratio of collagen fibers were significantly correlated. DiscussionBased on the present findings, changes in SWV during pregnancy were associated with placental fibrosis, and increased SWV in PIH and/or FGR cases might be influenced by infarction, ischemic changes, and inflammation, as well as fibrosis. In conclusion, the measurement of placental SWV is potentially useful to evaluate the condition of the placenta during pregnancy.

Shear wave elastography of placenta: in vivo quantitation of placental elasticity in preeclampsia.

We aimed to evaluate the utility of shear wave elastography (SWE) for assessing the placenta in preeclampsia disease. A total of 50 pregnant women in the second or third trimester (23 preeclampsia patients and 27 healthy control subjects) were enrolled in the study. Obstetrical grayscale and Doppler ultrasonography, SWE findings of placenta, and prenatal/postnatal clinical data were analyzed and the best SWE cutoff value which represents the diagnosis of preeclampsia was determined. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of preeclampsia were calculated based on SWE measurements. Mean stiffness values were much higher in preeclamptic placentas in all regions and layers than in normal controls. The most significant difference was observed in the central placental area facing the fetus where the umbilical cord inserts, with a median of 21 kPa (range, 3-71 kPa) for preeclampsia and 4 kPa (range, 1.5-14 kPa) for the control group (P < 0.01). The SWE data showed a moderate correlation with the uterine artery resistivity and pulsatility indices. The cutoff value maximizing the accuracy of diagnosis was 7.35 kPa (area under curve, 0.895; 95% confidence interval, 0.791-0.998); sensitivity, specificity, PPV, NPV, and accuracy were 90%, 86%, 82%, 92%, and 88%, respectively. Stiffness of the placenta is significantly higher in patients with preeclampsia. SWE appears to be an assistive diagnostic technique for placenta evaluation in preeclampsia.

Analysis of placental elasticity using virtual touch tissue quantification during pregnancy

Analysis of placental elasticity using virtual touch tissue quantification during pregnancy