Assessment of placental fractional moving blood volume using quantitative three-dimensional power doppler ultrasound

Assessing within-subject rates of change of placental MRI diffusion metrics in normal pregnancy

PURPOSE

Studying placental development informs when development is abnormal. Most placental MRI studies are cross-sectional and do not study the extent of individual variability throughout pregnancy. We aimed to explore how diffusion MRI measures of placental function and microstructure vary in individual healthy pregnancies throughout gestation.

METHODS

Seventy-nine pregnant, low-risk participants (17 scanned twice and 62 scanned once) were included. T2 -weighted anatomical imaging and a combined multi-echo spin-echo diffusion-weighted sequence were acquired at 3 T. Combined diffusion-relaxometry models were performed using both aT 2 * $$ {\mathrm{T}}_2^{\ast } $$ -ADC and a bicompartmentalT 2 * $$ {\mathrm{T}}_2^{\ast } $$ -intravoxel-incoherent-motion (T 2 * IVIM $$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$ ) model fit.

RESULTS

There was a significant decline in placentalT 2 * $$ {\mathrm{T}}_2^{\ast } $$ and ADC (both P < 0.01) over gestation. These declines are consistent in individuals forT 2 * $$ {\mathrm{T}}_2^{\ast } $$ (covariance = -0.47), but not ADC (covariance = -1.04). TheT 2 * IVIM $$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$ model identified a consistent decline in individuals over gestation inT 2 * $$ {\mathrm{T}}_2^{\ast } $$ from both the perfusing and diffusing placental compartments, but not in ADC values from either. The placental perfusing compartment fraction increased over gestation (P = 0.0017), but this increase was not consistent in individuals (covariance = 2.57).

CONCLUSION

Whole placentalT 2 * $$ {\mathrm{T}}_2^{\ast } $$ and ADC values decrease over gestation, although onlyT 2 * $$ {\mathrm{T}}_2^{\ast } $$ values showed consistent trends within subjects. There was minimal individual variation in rates of change ofT 2 * $$ {\mathrm{T}}_2^{\ast } $$ values from perfusing and diffusing placental compartments, whereas trends in ADC values from these compartments were less consistent. These findings probably relate to the increased complexity of the bicompartmentalT 2 * IVIM $$ {\mathrm{T}}_2^{\ast}\;\mathrm{IVIM} $$ model, and differences in how different placental regions evolve at a microstructural level. These placental MRI metrics from low-risk pregnancies provide a useful benchmark for clinical cohorts.

Characterization of Placental Microvascular Architecture by MV-Flow Imaging in Normal and Fetal Growth-Restricted Pregnancies

OBJECTIVES

To observe the microvascular architecture in the placental bed and explore the feasibility and clinical utility of MV-Flow imaging (Samsung Medison Co, Ltd, Seoul, Korea) during normal pregnancy and fetal growth restriction (FGR).

METHODS

Placental microvascular structure ultrasound imaging by MV-Flow was performed on 227 unaffected and 17 FGR fetuses between 11 and 41 weeks' gestation. A placental vascular index (VI^MV ) was acquired by application of various MV-Flow regions of interest (ellipse, rectangle, and manual trace). Unaffected control and FGR groups were assessed for umbilical artery, middle cerebral artery, and uterine artery pulsatility indices and the cerebroplacental ratio calculated by ultrasound.

RESULTS

No significant difference in the VI^MV by varying regions of interest or placental regions was observed in the control group. The VI^MV in the first trimester was lower than that in the second and third trimesters, with 5th through 95th percentile normal VI^MV reference values of 18.39 to 63.79 for 13.6 weeks and earlier, 28.53 to 66.64 for 14 weeks to 27 weeks 6 days, and 21.95 to 67.45 for 28 weeks and later. The VI^MV values in the FGR group were lower than those in the control group in the upper, middle, and lower parts of the placenta (mean ± SD, 24.9 ± 13.9 versus 45.0 ± 13.4; P < .01; 30.5 ± 16.1 versus 44.7 ± 14.3; P < .01; and 29.9 ± 17.4 versus 47.6 ± 12.2; P < .01, respectively). Higher umbilical artery and uterine artery pulsatility indices and a lower cerebroplacental ratio were found in the FGR group compared with the control group (P < .01).

CONCLUSIONS

MV-Flow technology can display and quantify placental microvascular architecture at the level of the stem villi and villous leaves, and the VI^MV provides for quantification of tissue vascularity. MV-Flow is a potentially powerful and promising tool to explore placental microvascular perfusion and provide new information on a host of pregnancy-related conditions.

Three-dimensional power Doppler ultrasonography indicates that increased placental blood perfusion during the third trimester is associated with the risk of macrosomia at birth

PURPOSE

To investigate the association between placental blood perfusion and the occurrence of macrosomia at birth.

METHODS

This was a prospective cohort study including women with singleton pregnancies that aimed to measure placental blood perfusion using three-dimensional (3D) power Doppler ultrasonography in the second and third trimester. We acquired three indices of placental blood flow, including vascularization index (VI), flow index (FI), vascularization flow index (VFI), along with routine two-dimensional (2D) biometric measurements, including abdominal circumference (AC) and estimated fetal weight (EFW). Pregnancy outcomes were divided into two groups: newborns with a normal birth weight and those with macrosomia. We then compared all of the recorded variables between these two groups. We also determined the predictive efficiency of each variable using receiver-operating characteristic (ROC) curves.

RESULTS

The placental 3D power Doppler indices, including VI and FI, were significantly higher in the third trimester of pregnancies developing macrosomia, but not during the second trimester, as compared to those with a normal birth weight. ROC curves analysis for third-trimester VI and FI suggested a slight ability to predict macrosomia; this was also the case for AC and EFW. Interestingly, VI showed high sensitivity and low specificity, while FI showed low sensitivity and high specificity; this was also the case for AC and EFW.

CONCLUSIONS

Three-dimensional power Doppler ultrasound indices were significantly higher during the third-trimester for pregnancies developing macrosomia. However, these indices had only moderate ability to predict macrosomia.

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.

First trimester placental volume and vascular indices in pregestational diabetic compared to nondiabetic pregnant women

AIM

Comparing placental volume (PV) and vascular indices in pregestational diabetic and nondiabetic pregnant women at 11 and 13 weeks gestation.

METHODS

A case-control study conducted at Ain Shams University Maternity Hospital in collaboration with Feto-maternal Unit for Ultrasound Assessment, Ain Shams University Maternity Hospital, Egypt. Ninety-two pregnant women divided into two groups: Group A included 46 women with pregestational diabetes mellitus and group B included 46 nondiabetic pregnant women as control. All participants had PV, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) calculated using three-dimensional (3D) ultrasonography and 3D power Doppler at 11 and 13 weeks of pregnancy.

RESULTS

At 11 weeks, the mean VI, FI and VFI in diabetic group (17.70 ± 12.62, 40.72 ± 11.03 and 7.77 ± 6.37, respectively) were insignificantly higher than in nondiabetic group (12.14 ± 12.62, 34.59 ± 9.66 and 6.52 ± 14.20, respectively) while mean PV in diabetic group (26.90 ± 14.74) was insignificantly lower than in nondiabetic group (27.53 ± 17.46). Also at 13 weeks, the results were not different as the mean VI, FI and VFI in diabetic group (16.51 ± 9.81, 42.52 ± 7.47 and 8.12 ± 7.55, respectively) were insignificantly higher than in nondiabetic group (16.37 ± 14.17, 40.29 ± 17.52 and 7.08 ± 4.35, respectively), and mean PV in diabetic group (52.04 ± 17.95) was insignificantly lower than in nondiabetic group (54.46 ± 17.85). There was strong positive correlation between HbA1C level and VFI measured at 13 weeks gestation.

CONCLUSIONS

Placental indices in early pregnancy do not seem to be useful markers to anticipate placental pathology in pregestational diabetes, however there might be a role for HbA1C level measurement to anticipate such complications.

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.

Three-dimensional power Doppler ultrasound evaluation of placental blood flow in normal monochorionic diamniotic twin pregnancies

Background

Monochorionic diamniotic (MCDA) twin pregnancies are at higher risk of adverse outcomes and complications, which are attributed to the influence of placental morphology in MCDA twins. Monitoring of placental function is an important index for clinical decisions. The aim of our study was to evaluate the placental blood flow estimated using three-dimensional power Doppler (3D-PD) ultrasound and the vascular indices distribution with gestational age (GA) in normal MCDA twin pregnancies.

Methods

One hundred four MCDA twin pregnancies and 106 singleton pregnancies (GA range, 14–32 weeks) were included in this prospective study. 3D-PD volume data of each fetus was obtained separately from the placenta at the site of umbilical cord insertion. We analyzed the volume data using sonobiopsy technique. The placental vascularization index (VI), flow index (FI) and vascularizationflow index (VFI), were auto-calculated. The means and standard deviation values of three vascular indices per fetus were calculated and regression analysis of the vascular indices as a function of GA was performed in twin pregnancies. The vascular indices of twin and singleton pregnancies were compared using independent t-test.

Results

There were no significant differences in VI, FI or VFI among the fetuses of twins (p > 0.05). These vascular indices increased over the course of pregnancy (p < 0.05). We obtained the regression equations for the indices as a function of GA in days: VI = exp. (4.369–28.533/GA) (R² = 0.699, p < 0.05), FI = exp. (3.916–13.003/GA) (R² = 0.511, p < 0.05), and VFI = exp. (3.577–37.468/GA) (R² = 0.675, p < 0.05). There were no significant differences in three vascular indices between MCDA twin and singleton groups (p > 0.05).

Conclusions

3D-PD placental data using sonobiopsy technique could reflect the placental blood flow of each twin, which could be applied to the study of placental perfusion in MCDA twin pregnancies. This study also presented the vascular indices distribution with GA in normal twin pregnancies, which might be useful for early detection of MCDA complications.

Association Between Endometrial/Subendometrial Vasculature and Embryo Transfer Outcome: A Meta-analysis and Subgroup Analysis

OBJECTIVES

To examine the association between endometrial/subendometrial vasculature and in vitro fertilization-embryo transfer (IVF-ET) and frozen embryo transfer (FET) outcomes.

METHODS

A meta-analysis of studies using endometrial/subendometrial 3-dimensional ultrasound and power Doppler angiography was performed to examine the vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) in pregnant and nonpregnant women. Ten articles were analyzed, including 895 pregnant women and 882 nonpregnant women.

RESULTS

A subgroup analysis of the measuring time showed that the endometrial VI (standardized mean difference [SMD], 0.57; 95% confidence interval [CI], 0.40, 0.74; P < .00001), FI (SMD, 0.56; 95% CI, 0.33, 0.78; P < .00001), and VFI (SMD, 0.45; 95% CI, 0.28, 0.61; P < .00001) measured on the ET day, but not on the human chorionic gonadotropin (hCG) trigger day, were significantly higher in pregnant than nonpregnant women. Additionally, the subendometrial FI was significantly increased in pregnant women on the both hCG day (SMD, 0.68; 95% CI, 0.31, 1.06; P = .004) and ET day (SMD, 0.30; 95% CI, 0.08, 0.52; P = .007). A subgroup analysis of cycle type showed that the endometrial VI (SMD, 0.52; 95% CI, 0.30, 0.74; P < .00001), FI (SMD, 0.44; 95% CI, 0.22, 0.66; P = .0001), and VFI (SMD, 0.45; 95% CI, 0.23, 0.67; P = .03) on the ET day were significantly increased in pregnant women in the FET subgroup.

CONCLUSIONS

The subendometrial FI on the hCG day and endometrial VI, FI, and VFI on the ET day are potentially associated with pregnancy occurrence during IVF-ET. The endometrial VI, FI, and VFI could help identify appropriate timing for FET. However, the accuracy of these indices in predicting pregnancy occurrence must be further evaluated in additional large-scale studies.

Nonpresenting Dichorionic Twins and Placental Vascular Malperfusion

OBJECTIVE

To explore the hypothesis that selective placental pathology affecting the nonpresenting twin is a significant contributory factor mediating the smaller size at birth of nonpresenting dichorionic twins.

METHODS

We conducted a retrospective cohort study of all dichorionic twin deliveries in a single tertiary center between 2002 and 2015 where by departmental policy, all placentas from multifetal gestations are routinely sent for pathologic examination. Maternal charts, neonatal charts, and pathology reports were reviewed. Placental abnormalities were classified into lesions associated with maternal vascular malperfusion, fetal vascular malperfusion, placental hemorrhage, and chronic villitis. Comparison of neonatal outcomes and placental abnormalities was made between all nonpresenting and all presenting twins as well as within twin pairs.

RESULTS

A total of 1,322 women with dichorionic twins were studied. Nonpresenting twins were smaller at birth compared with the presenting cotwin starting at 32 weeks of gestation (birth weight [±standard deviation] 2,224±666 g compared with 2,278±675 g, P=.036). Nonpresenting twins had smaller placentas (361±108 g compared with 492±129 g, P<.001) as early as 24 weeks of gestation. Nonpresenting twins had higher odds for any placental abnormality (adjusted odds ratio [OR] 1.91, 95% confidence interval [95% CI] 1.63-2.23), small placenta (adjusted OR 4.69, 95% CI 3.75-5.88), and maternal vascular malperfusion (OR 2.75, 95% CI 2.32-3.27) compared with their presenting cotwins. In nonpresenting twins, the presence of maternal vascular malperfusion pathology was associated with lower birth weight compared with their presenting cotwin during the third trimester.

CONCLUSION

The lower birth weight of nonpresenting fetuses in dichorionic twin pregnancies is correlated with a higher rate of placental maternal vascular malperfusion pathology.

Placental vascular indices (VI, FI and VFI) in intrauterine growth retardation (IUGR). A pooled analysis of the literature

OBJECTIVE

I performed a systematic review and pooled analysis to study the utility of the placental vascular flow indices vascularization index (VI), flow index (FI) and vascularization flow index (VFI) in the prediction or identification of in-utero growth restriction (IUGR).

METHOD

A comprehensive literature search for relevant studies was conducted using PubMed and Web of Knowledge databases. Included were cohort or case-control studies which reported (1) the statistical position and dispersion of vascular indices in a population of normal pregnancies at various trimesters of pregnancy; (2) correlation between vascular indices and gestational age; or (3) the vascular index values stratified according to the presence of SGA/IUGR versus a population of controls.

RESULTS

Seven studies met the criteria of inclusion, for a total of 788 controls and 82 SGA cases in the first trimester, and 169 controls and 80 IUGR cases essentially enrolled in the 3rd trimester. After normalization of the means, the pooled detection rates (DRs) at a 10% false positive rate were 32.5%, 53.8% and 51.0%, respectively, for the vascular indices VI, FI and VFI in the third trimester. No significant discriminant ability was detected in the first trimester.

CONCLUSION

A significant DR for IUGR was demonstrated only in the third trimester, thus limiting the utility of vascular indices to predict IUGR. VI and VFI are more reliable and yield better DR and better performance in terms of homogeneity than FI and should be evaluated in the management of third trimester IUGR and prediction of outcome.

Placental vascularization alterations in hypertensive disorders complicating pregnancy (HDCP) and small for gestational age with HDCP using three-dimensional power doppler in a prospective case control study

Background

Hypertensive disorders complicating pregnancy (HDCP) continues to be a leading cause of maternal and neonatal mortality and morbidity. The clinical value of placental three-dimensional power Doppler (3DPD) in assessing HDCP requires further confirmation. The research was developed to assess changes of placental vascularity in HDCP using 3DPD and to investigate the placental vascularity in small for gestational age (SGA) compared with not-SGA in patients with HDCP.

Methods

There were 126 normotensive and 128 hypertensive pregnant women included in this prospective case–control study from March 2011 to March 2013. Pregnant women underwent 3DPD. Vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were obtained. The placental 3DPD indices, umbilical artery systolic and diastolic ratio (S/D) and pregnancy outcomes were compared between the groups.

Results

The placental VI and VFI were significantly lower in hypertensive women compared with normotensive women (P < 0.001 and P = 0.014, respectively), and these parameters were significantly reduced in severe preeclampsia (P < 0.001 and P = 0.003, respectively). A weak correlation was found between VI and umbilical artery S/D in HDCP group (r = -0.277, P = 0.001). In HDCP population, neonates who were postnatally diagnosed with SGA had lower VI (P = 0.041) and higher S/D (P < 0.001).

Discussion

The placental vascularity indices decreased in hypertensive women and the reduction inplacental perfusion was consistent with the severity of the hypertensive disorder. The associations betweenplacental vascularization and umbilical artery impedance may be valuable for further researches and arerequired confirmation. The significant differences in the 3DPD placental vascularization between SGA andnot-SGA in hypertensive pregnancy population may show some clinical importance that we could use tobetter assess or predict the progression and adverse outcomes in the future. Although 3DPD quantificationhas been widely used in multiple publications, we have to acknowledge its limitations.

Conclusions

The intraplacental vascularization was poor in HDCP, and especially in severe preeclampsia. Neonates with SGA had poor placental vascularization and higher umbilical artery S/D. Further studies should focus on the clinical assessment of placental 3DPD as well as a combination of placental 3DPD and other fetal Doppler indices to better predict the development and outcomes of preeclampsia.

Three-dimensional placental volume and mean grey value: Normal ranges in a Turkish population and correlation with maternal serum biochemistry and Doppler parameters

The aim of this study is to evaluate the relationship between three-dimensional (3D) ultrasound measurements of placenta at 11-13(6) weeks' gestation and maternal serum levels of pregnancy associated plasma protein-A (PAPP-A), free beta human chorionic gonadotrophin (fβhCG), Doppler parameters in early pregnancy. This prospective study consisted of 334 singleton pregnancies at 11-13(6) weeks' gestation. Placental volume and placental volumetric mean grey values were evaluated. The placental volume (cm(3)) was analysed using the Virtual Organ Computer-aided AnaLysis (VOCAL) imaging program and 3D histogram was used to calculate the volumetric mean grey value (%). Mean maternal age was 28.35 ± 7.55. Mean gestational age was 12.29 ± 0.68 weeks. Placental volume was 77.04 ± 35.74 cm(3). Mean grey value of the placenta was 34.38 ± 8.02%. Correlation analysis revealed that placental volume was significantly correlated with the crown-rump length (r = 0.173, p = 0.002), gestational week (r = 0.116, p = 0.036), ductus venosus pulsatility index (r = -0.101, p = 0.04) and maternal weight (r = 0.099, p = 0.037). There was a significant relation between the mean grey value of the placenta and maternal age (r = 0.131, p = 0.02), nuchal translucency (r = -0.109, p = 0.048), PAPP-A (r = 0.108, p = 0.04) and fβhCG (r = 0.104, p = 0.042). Volumetry of the placenta can be carried out with a high percentage of 1st trimester pregnancies. Volumetry during the 1st trimester could be helpful because of the less advanced state of placentation. This examination is easy to perform and the measurements can be acquired correctly and quickly.

Quantitative assessment of placental vasculature and placental volume in normal pregnancies with the use of 3D Power Doppler

PURPOSE

The aim of the study was to determine reference values for placental vascular indices and placental volume according to gestational age.

MATERIAL/METHODS

The assessment of placental vascular indices and placental volume using 3D Power Doppler and the Virtual Organ Computer-aided Analysis (VOCAL) technique was performed on 100 normal fetuses between 22 and 41 weeks of gestation. In this study the method of the individual setting of the power Doppler gain value was used. Only patients with entirely visualized placenta were included in the study.

RESULTS

No statistically relevant difference in the values of placental vascular indices and placental volume between different localizations of the placenta was detected. No statistically significant changes to placental vascular indices depending on gestational age were found. It enabled to determine the 10th, 50th and 90th percentile values for the vascularization index (VI), flow index (FI), vascularization-flow index (VFI), which are independent of gestational age. No correlation was found between placental volume and placental vascular indices.

CONCLUSIONS

The values of placental vascular indices are constant between the 22nd and 41st week of a normal pregnancy. Placental volume measured with the use of the VOCAL program increases between 22nd and 41st week of a normal pregnancy. In a normal pregnancy the placental vasculature increases adequately to the increase of its volume. The method of the individual setting of the power Doppler gain value makes it possible to achieve comparable values of placental vascular indices regardless of the distance between the probe and the placenta.

Three-dimensional Evaluation of the Placenta: Review of the Literature

The introduction of the three-dimensional (3D) ultrasound made feasible the quantitative and qualitative evaluation of the placenta's characteristics like the volume, the surface rendered imaging, the vascularization and the blood flow. These novel techniques may assist the early detection of pregnancies at high risk for fetal growth restriction (FGR), pre-eclampsia (PET) and pregnancy-induced hypertension (PIH) and help clinicians to detect pregnancies at risk earlier and to assess new therapeutic strategies in order to prevent adverse pregnancy outcomes. However, in this new technique there are still limitations regarding the assessment of the placenta employing 3D ultrasound in everyday clinical practice. In the following article, we perform a review of the literature regarding the importance of 3D evaluation of the placenta in pregnancy.

How to cite this article

Natsis S, Antsaklis P, Antsaklis A, Kurjak A. Three-dimensional Evaluation of the Placenta: Review of the Literature. Donald School J Ultrasound Obstet Gynecol 2013;7(1):73-79.

Three-dimensional Doppler evaluation of single spherical samples from the placenta: intra- and interobserver reliability

OBJECTIVE

To evaluate the intra- and interobserver reliability of assessment of three-dimensional power Doppler (3D-PD) indices from single spherical samples of the placenta.

METHODS

Women with singleton pregnancies at 24-40 weeks' gestation were included. Three scans were independently performed by two observers; Observer 1 performed the first and third scan, intercalated by the scan of Observer 2. The observers independently analyzed the 3D-PD datasets that they had previously acquired using four different methods, each using a spherical sample: random sample extending from basal to chorionic plate; random sample with 2 cm(3) of volume; directed sample to the region subjectively determined as containing more color Doppler signals extending from basal to chorionic plate; or directed sample with 2 cm(3) of volume. The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were evaluated in each case. The observers were blinded to their own and each other's results. Additional evaluation was performed according to placental location: anterior, posterior and fundal or lateral. Intra- and interobserver reliability was assessed by intraclass correlation coefficients (ICC).

RESULTS

Ninety-five pregnancies were included in the analysis. All three placental 3D-PD indices showed only weak to moderate reliability (ICC < 0.66 and ICC < 0.48, intra- and interobserver, respectively). The highest values of ICC were observed when using directed spherical samples from basal to chorionic plate. When analyzed by placental location, we found lower ICCs for lateral and fundal placentae compared to anterior and posterior ones.

CONCLUSION

Intra- and interobserver reliability of assessment of placental 3D-PD indices from single spherical samples in pregnant women greater than 24 weeks' gestation is poor to moderate, and clinical usefulness of these indices is likely to be limited.

Diagnosis of ovarian metastasis from gestational trophoblastic neoplasia by 3D power Doppler ultrasound and dynamic contrast-enhanced magnetic resonance imaging: case report

Choriocarcinoma is a highly malignant disease of trophoblastic cells, which affects young women in the reproductive years. The main sites of metastasis from choriocarcinoma are lung, vagina, liver, gastrointestinal tract and kidneys, and the involvement of the ovaries is extremely rare. The diagnosis of ovarian metastasis is made mainly by two-dimensional ultrasonography (2DUS) with color Doppler, which shows a large vessel in the center of the mass. The three-dimensional power Doppler ultrasound (3D power Doppler) and dynamic contrast-enhanced magnetic resonance imaging (MRI) are new diagnostic modalities not yet published in literature. We report a case of metastatic choriocarcinoma with left ovary involvement in a 48-year-old woman with history of molar pregnancy and irregular follow-up of this disease. We emphasize the main findings by 2DUS with color Doppler, 3D power Doppler and dynamic contrast-enhanced MRI. 3D power Doppler is able to improve the assessment of anatomical relationships of vessels with the ovarian mass, while the resonance angiography allows us to evaluate the anatomic relations of the mass and adjacent structures, as well as the iliac vessels. The 3D power Doppler and dynamic contrast-enhanced MRI are promising methods in the evaluation of metastasis arising from gestational trophoblastic tumors.

Transvaginal 3-d power Doppler ultrasound evaluation of the fetal brain at 10-13 weeks' gestation

The objective of this study was to measure the fetal brain volume (FBV) and vascularization and blood flow using transvaginal 3-D power Doppler (3DPD) ultrasound late in the first trimester of pregnancy. 3DPD ultrasound examinations with the VOCAL imaging analysis program were performed on 36 normal fetuses from 10-13 weeks' gestation. FBV and 3DPD indices related to the fetal brain vascularization (vascularization index [VI], flow index [FI] and vascularization flow index [VFI]) were calculated in each fetus. Intra- and interclass correlation coefficients and intra- and interobserver agreements of measurements were assessed. FBV was curvilinearly correlated well with the gestational age (R2 = 0.861, p < 0.0001). All 3-D power Doppler indices (VI, FI and VFI) showed no change at 10-13 weeks' gestation. FBV and all 3-D power Doppler indices (VI, FI and VFI) showed a correlation > 0.82, with good intra- and interobserver agreement. Our findings suggest that 3-D ultrasound is a superior means of evaluating the FBV in utero, and that 3-D power Doppler ultrasound histogram analysis may provide new information on the assessment of fetal brain perfusion.

Comparative analysis of placental vasculature and placental volume in normal and IUGR pregnancies with the use of three-dimensional Power Doppler

Objectives

To evaluate the differences in placental vascular indices and placental volume between normal and IUGR pregnancies.

Methods

A prospective study was conducted on a group of 100 normal and 20 IUGR pregnancies between 22 and 42 weeks of gestation. For the purpose of evaluation of placental volume and placental vascular indices, we applied 3D Power Doppler and VOCAL technique. Only patients with entirely visualized placenta were included in the study.

Results

A comparative analysis of vascularization index (VI), vascularization flow index (VFI), flow index (FI), and placental volume (PV) revealed statistically significant differences between normal and IUGR pregnancies.

In normal pregnancies, the volume of the placenta was on average 92.42 cm³ larger than in pregnancies complicated by IUGR. Receiver operating characteristic (ROC) curves were used to evaluate the clinical usefulness of placental vascular indices and placental volume for discriminating IUGR and normal pregnancies. It was concluded that the VI, VFI, PV, FI parameters are the best discriminants, with the cut-off values of 5.30, 2.30, 199, and 36.0, respectively.

Conclusions

The quantitative assessment of placental vasculature and placental volume by means of 3D Power Doppler and VOCAL technique is an adjunctive modality for differentiation between normal and IUGR pregnancies. Our findings further suggest that the vascularization index (VI) and vascularization flow index (VFI) are the best parameters with the most favorable discriminating potential for proper identification of IUGR pregnancies.

Review: Feto-placental vascularization: a multifaceted approach

Doppler Ultrasound allows the in vivo study of feto-placental hemodynamics. Doppler flow velocity waveforms (FVW's) obtained from the umbilical arteries reflect downstream blood flow impedance, thus giving indirect evidence of vascular villous tree characteristics. Pulsatility Index, which quantifies FVW's, decreases throughout normal pregnancy, indicating decreasing impedance and is often higher in cases of fetal growth restriction (FGR). Different approaches (morphometrical, morphological, mathematical, immunohistochemical and molecular) have contributed to elucidation of which anomalies of the vascular villous tree underlie Doppler findings. 3D ultrasound may be useful in the study of feto-placental perfusion. However, the unsolved question is why developmental villous tree anomalies occur. Crucial to the success of future research is definition of the population studied based on the uniform and correct definition of FGR.

Análise da reprodutibilidade do Doppler de amplitude tridimensional na avaliação da circulação do cérebro fetal

OBJETIVO: Avaliar a reprodutibilidade intra e interobservador do Doppler de amplitude tridimensional (3D power Doppler) na avaliação do fluxo sanguíneo cerebral do território da artéria cerebral média. MATERIAIS E MÉTODOS: Foi realizado estudo transversal com 20 gestantes normais entre 26 e 34 semanas. O território da artéria cerebral média mais próximo ao transdutor foi selecionado e o volume foi calculado utilizando-se o método Virtual Organ Computer-aided AnaLysis. Posteriormente, obtiveram-se os índices do 3D power Doppler: índice de vascularização (VI), índice de fluxo (FI) e índice de vascularização-fluxo (VFI). Utilizaram-se, para os cálculos, o coeficiente de correlação intraclasse (CCI) e gráficos de Bland-Altman. RESULTADOS: Foi observada boa concordância intra e interobservador, com CCI > 0,90 para todos os índices do 3D power Doppler: VI [CCI = 0,992 (IC 95%: 0,981-0,997)], FI [CCI = 0,999 (IC 95%: 0,998-0,999)], VFI [CCI = 0,995 (IC 95%: 0,987-0,998)]. Reprodutibilidade interobservador: VI [CCI = 0,988 (IC 95%: 0,970-0,995)], FI [CCI = 0,999 (IC 95%: 0,997-1,000)], VFI [CCI = 0,994 (IC 95%: 0,994-0,998)]. CONCLUSÃO: O 3D power Doppler mostrou-se um método prático, fácil e com boa reprodutibilidade intra e interobservador, com o IF evidenciando a melhor concordância intra e interobservador

Reproducibility of regional placental vascularity/perfusion measurement using 3D power Doppler

OBJECTIVES

To assess reproducibility and regional variability of placental perfusion measurement using three-dimensional (3D) power Doppler VOCAL() (Virtual Organ Computer-aided AnaLysis).

METHODS

Twenty pregnant women at 26-34 weeks' gestation with normally grown, biophysically normal, singleton pregnancies with anterior placentae had placental power Doppler mapping data stored digitally from each of the four placental quadrants. Each was imaged by two investigators, with two datasets stored per investigator per quadrant. 5760 data values from the 320 datasets were evaluated by the same two investigators. Power Doppler imaging of the placental cord insertion was performed to generate a value for standardization as 'fractional moving blood volume' if appropriate. The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were calculated from spherical regions-of-interest to assess reproducibility within and between quadrants and between investigators for both acquisition and analysis.

RESULTS

We found extensive variability for all readings. For repeated measurements within the same dataset the intra-analyzer intraclass correlation coefficient (ICC) range was: 0.24-0.57 for VI, 0.33-0.78 for FI and 0.12-0.48 for VFI. The corresponding interanalyzer ICC range was: 0.38-0.92 for VI, 0.40-0.85 for FI and 0.10-0.92 for VFI. The intra-acquirer variability (paired t-test) mean differences range was: - 3.91 to 4.71 for VI, - 2.68 to 3.31 for FI and - 2.23 to 2.78 for VFI; the corresponding interacquirer variability (paired t-test) range was: - 1.92 to 5.18 for VI, - 3.06 to 2.04 for FI and - 1.69 to 2.60 for VFI. The regional variability range (coefficient of variation) was: 6.28-126.34% for VI, 2.26-49.01% for FI and 6.09-151.55% for VFI. For all analyzed data, FI showed least variability and cord values for VI were consistently 100% (mean VFI, 98.4 and 98.8 between observers).

CONCLUSIONS

There is insufficient evidence to support the meaning, reliability or reproducibility of VOCAL (VI, FI or VFI) as a tool to quantify placental perfusion, despite its use in multiple publications and journal submissions. There is poor reproducibility at the most fundamental level. Further investigation into the reproducibility of placental perfusion and quantification using VOCAL is required before development and application as a clinically useful tool.

Reprodutibilidade interobservador dos índices vasculares do Doppler de amplitude tridimensional do embrião entre 7 e 10 semanas e 6 dias de gestação

OBJETIVO: Avaliar a reprodutibilidade interobservador dos índices de vascularização do Doppler de amplitude tridimensional (Doppler de amplitude 3D) no primeiro trimestre de gestação. MATERIAIS E MÉTODOS: Realizou-se estudo de reprodutibilidade com 32 gestantes normais entre 7 e 10 semanas e 6 dias. Para o cálculo do volume tridimensional dos embriões utilizou-se o método VOCAL (Virtual Organ Computer-aided AnaLysis) com ângulo de rotação de 12°. Em seguida obtiveram-se, automaticamente, os três índices vasculares do Doppler de amplitude 3D: índice de vascularização (VI), índice de fluxo (FI) e índice de vascularização e fluxo (VFI). Para o cálculo da variabilidade interobservador, um examinador realizou uma segunda medida dos 32 embriões e um segundo examinador realizou uma terceira medida dos mesmos volumes, ambos desconhecendo os resultados do outro. Utilizaram-se, para análise estatística, o coeficiente de correlação intraclasse (CCI) e gráficos de Bland-Altman. RESULTADOS: Observou-se boa reprodutibilidade interobservador dos três índices vasculares. O VI apresentou CCI = 0,9 e média da diferença = -1,1; o FI apresentou CCI = 0,9 e média da diferença = -0,5; e o VFI apresentou CCI = 0,9 e média da diferença = -1,1. CONCLUSÃO: Os índices vasculares do Doppler de amplitude 3D do embrião no primeiro trimestre de gestação foram altamente reprodutíveis, em especial o FI.

First-trimester placental volume and vascularization measured by 3-dimensional power Doppler sonography in pregnancies with low serum pregnancy-associated plasma protein a levels

OBJECTIVE

The purpose of this study was to investigate the first-trimester placental volume and 3-dimensional (3D) power Doppler vascularization of pregnancies with low serum pregnancy-associated plasma protein A (PAPP-A) levels and to relate these findings to pregnancy outcomes.

METHODS

Three-dimensional power Doppler sonography of the placenta was performed at gestational ages of 11 weeks to 13 weeks 6 days in 84 pregnancies with PAPP-A concentrations of less than 0.4 multiple of the median (MoM). With a standardized setting, the placental volume and vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) were calculated and related to pregnancy outcomes.

RESULTS

Pregnancy outcomes were as follows: 57 pregnancies with birth weights at or above the 10th percentile (group A), 16 pregnancies with birth weights below the 10th percentile and normal Doppler findings in the umbilical artery throughout gestation (group B), and 11 pregnancies with birth weights below the 10th percentile and abnormal umbilical Doppler findings later in gestation (group C). No differences were found in PAPP-A levels among groups. Placental volume values were significantly lower than reference limits, but no differences were found between groups. In groups A and B, there were no significant differences in 3D Doppler indices. However, these indices were significantly lower in group C (VI mean difference, -1.904; P < .001; FI mean difference, -1.939; P < .001; VFI mean difference, -1.944; P < .001). Placental vascular indices were significantly related to the severity of intrauterine growth restriction (IUGR; VI, r = 0.438; P < .001; FI, r = 0.482; P < .001; VFI, r = 0.497; P < .001) but not to the PAPP-A MoM and placental volume values.

CONCLUSIONS

Low serum maternal PAPP-A levels are associated with altered 3D placental Doppler indices, and these changes are related to subsequent development of IUGR and adverse pregnancy outcomes.

Centrality of the umbilical cord insertion in a human placenta influences the placental efficiency

GOAL

We assess the effect on placental efficiency of the non-centrality of the umbilical cord insertion and on chorionic vascular distribution to determine if cord centrality measurably affects placental function as reflected in birth weight.

MATERIALS AND METHODS

1225 placentas collected from a prospective cohort had digital photographs of the chorionic plate. Of these, 1023 were term, 44 had velamentous cord insertion and 12 had missing clinical data, leaving N=967 (94.5%) cases for analysis. Mathematical tools included a dynamical stochastic growth model of placental vasculature, Fourier analysis of radial parameterization of placental perimeters, and relative chorionic vascular density (a measure of "gaps" in the vascular coverage) derived from manual tracings of the fetal chorionic surface images. Bivariate correlations used Pearson's or Spearman's rank correlation as appropriate, with p<0.05 considered significant.

RESULTS

The correlation of the standard deviation of the placental radius (a measure of non-roundness of the placenta) with cord displacement was negligible (r=0.01). Empirical simulations of the vascular growth model with cord displacement showed no deviation from a normal round-to-oval placental shape for cord displacement of 10-50% of placental radius. The correlation of the metabolic scaling exponent beta with cord displacement measured by Fourier analysis is 0.17 (p<0.001). Analysis of the chorionic vascular density in traced images shows a high correlation of the relative vascular distance with cord displacement: 0.59 in one set of 12 images, and 0.20 in the other set of 28 images.

CONCLUSION

Non-central cord insertion has little measurable correlation with placental shape in observed or simulated placentas. However, placentas with a displaced cord show a markedly reduced transport efficiency, reflected in a larger value of beta and hence in a smaller birth weight for a given placental weight. Placentas with a non-central cord insertion have a sparser chorionic vascular distribution, as measured by the relative vascular distance. Even if typically a placenta with a non-central insertion is of a normal round shape, its vasculature is less metabolically effective. These findings demonstrate another method by which altered placental structure may affect the fetal environment, influencing birth weight and potentially contributing to later health risks.

Embryo vascularization by three-dimensional power Doppler ultrasonography at 7-10 weeks of pregnancy

AIM

Assess vascular indices of 7-10 week embryos using three-dimensional power Doppler (3DPD) and correlate them with the crown-rump length (CRL).

METHODS

This cross-sectional study included 65 healthy pregnancies between 7 and 10 weeks. The three-dimensional volume of the embryo was obtained using an endocavitary volumetric transducer and the VOCAL (Virtual Organ Computer-aided Analysis) method, with a 12 degree rotation angle and 15 sequential planes. The vascularization (VI), flow (FI) and the vascular and flow (VFI) indices were obtained using 3DPD and the mean, median, standard deviation, maximum and minimum values were calculated for each gestational age. Pearson's correlation coefficient (r) was used to evaluate the correlation between vascular indices and CRL.

RESULTS

The VI ranged from 0.77 to 41.67, mean 14.68 (+/-8.60), the FI went from 25.71 to 139.50, mean 90.61 (+/-21.51) and the VFI from 0.20 to 81.57, mean 15.69 (+/-12.42). The correlation between CRL and all 3D power Doppler vascular indices was low (VI - r=-0.073, P=0.566; FI - r=0.173, P=0.168 and VFI - r=-0.004, P=0.974).

CONCLUSION

3D power Doppler vascular indices in 7-10 week embryos do not correlate with CRL.

Evaluation of the utero-placental circulation by three-dimensional Doppler ultrasound in the second trimester of normal pregnancy

OBJECTIVE

To define normative data with three-dimensional (3D) Doppler ultrasound in the second trimester spiral arteries and placental volume blood flow.

METHODS

An entry criterion was a documented singleton pregnancy at 14-25 weeks with normal outcome. Each patient had a 3D power Doppler exam. Automatic volume acquisition of the placental and spiral arteries blood flow was obtained. We calculated vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The patients were further divided into subgroups based on two gestational week intervals. The outcome measure was normal pregnancy outcome.

RESULTS

One hundred ninety-nine patients were included in this study. Placental and spiral arteries vascular indices slowly increased indicating progressive development of vascular network and increase in the volume blood flow. The range for placental VI was 11.43-14.63, FI was 37.44-40 and VFI was 4.77-6.06. The range for spiral arteries VI was 19-20.91, FI was 39.66-41.1 and VFI was 8.49-8.92. The mean gestational age at delivery was 38.18 weeks.

CONCLUSION

We defined normal 3D power Doppler vascular indices in pregnancies between 14 and 25 weeks of singleton gestation. The study indicated that placental and spiral arteries volume blood flow increased with the advancement of gestational age.

Evolution of 3-D power Doppler indices of fetal brain in normal pregnancy

We assessed the vascular indices of the anterior territory of the middle cerebral artery (MCA) in normal pregnancies using 3-D power Doppler (3DPD). A cross-sectional study was carried out on 90 normal pregnancies between 24 and 35 weeks. All examinations were performed by a single operator using a volumetric transducer. The anterior territory of the MCA was scanned and the volumes were captured using 3DPD. The sphere mode of the VOCAL program was used to calculate the following vascular indices: vascularization index (VI), flow index (FI) and vascularization and flow index (VFI). Models of polynomial regression and Pearson's correlation coefficient were used to evaluate the correlation between gestational age (GA) and the vascular indices. The 3DPD vascular indices had a low correlation with gestational age (VI - r = 0.324, p = 0.002; FI - r = 0.375, p < 0.001; VFI - r = 0.374, p < 0.001). There was a low correlation between GA and the 3DPD vascular indices of the anterior territory of the MCA.

Three-dimensional sonography of the placental and uterine spiral vasculature: influence of maternal age and parity

PURPOSE

: To test the influence of maternal age and parity on placental volume and uterine spiral vasculature volume, their mean gray value, and 3-dimensional power Doppler (3DPD) indices in normal pregnancy.

METHODS

: Women with a gestational age of 14-25 weeks were included in the study. Exclusion criteria included posterior placenta, structural or chromosomal anomaly, pregnancy complications, and unknown pregnancy outcome. 3D sonograms of the placenta and uterine spiral vasculature were obtained. Virtual Organ Computer-aided AnaLysis imaging software was used to calculate the volumes, mean gray value, and 3DPD indices.

RESULTS

: The study included 199 women, the majority of whom were Filipino, Japanese, or part Hawaiian. The placental volume, uterine spiral vasculature volume, mean gray value, and 3DPD indices were similar in all women regardless of maternal age. However, uterine spiral vasculature volume was significantly larger in women younger than 25 years, compared with women 35 years of age and older. Parity influenced all placental 3DPD indices, whereas placental volume, uterine spiral vasculature volume, mean gray value, and 3DPD indices remained unaffected.

CONCLUSION

: Maternal age influenced uterine spiral vasculature volume, whereas parity influenced all placental 3DPD indices.

Is three-dimensional power Doppler ultrasound useful in the assessment of placental perfusion in normal and growth-restricted pregnancies?

OBJECTIVES

To investigate three-dimensional (3D) power Doppler ultrasound indices in the assessment of placental perfusion and their relationship to gestational age (GA), placental position and umbilical artery Doppler flow velocity waveform (FVW) patterns in normal and intrauterine growth-restricted (IUGR) pregnancies.

METHODS

Forty-five pregnant women at 23-37 weeks' gestation were studied, of whom 30 had IUGR and 15 were controls. Nine of the IUGR group had normal umbilical FVWs (NED), nine had abnormal patterns but positive end-diastolic velocities (PED) and 12 had absent or reversed end-diastolic velocities (AED). Placental position was assessed as being posterior, anterior or lateral. 3D power Doppler indices related to placental perfusion (vascularization index (VI), vascularization flow index (VFI) and flow index (FI)) were obtained from five different sampling sites in each placenta.

RESULTS

VI, VFI and FI were not significantly dependent on GA or placental position. VI and VFI were significantly lower in PED and AED cases compared with controls, while FI was reduced in the AED group only. VI and VFI showed high variability between different sampling sites within each placenta, while the variability of FI was much lower.

CONCLUSIONS

3D power Doppler sonography can provide new insights into placental pathophysiology. FI, which identifies the most severe cases of placental impairment, appears to be the most reliable index because of its low intraplacental variability. Further studies are needed to verify its accuracy when applied in clinical practice as a substitute for or an adjunct to umbilical artery Doppler studies.

Placenta: angiogenesis and vascular assessment through three-dimensional power Doppler ultrasonography

The placenta is fundamental for fetal development. It combines the functions of an endocrine organ, kidneys, lungs and intestines, purifying catabolites, oxygenating and nourishing the conceptus. Its fetal portion is the largest part develops from the chorionic sac. The maternal portion, which is smaller, is originated in the endometrium, more specifically in the decidua basalis. The placenta starts its function closer to the fourth week of gestation, when anatomical arrangements for the physiological exchanges are already established. The circulatory function of the placenta appears at an early stage of embryo-placental development and it is strongly related to fetal growth, to the placental size and to uterine and umbilical blood flows. Therefore, an adequate placental angiogenesis is critical for the establishment of a normal placental vascularization with consequent normal development of the fetus. In this review article, the authors discuss about placental ontogeny, focusing on the main aspects of its normal development, and about the recent advances in ultrasonography for the study of the vascular architecture of the placenta through three-dimensional power Doppler ultrasonography.

State of the art: non-invasive ultrasound assessment of the uteroplacental circulation

Impaired trophoblastic invasion of the maternal spiral arteries is associated with increased risk for subsequent development of intrauterine growth restriction, preeclampsia, and placental abruption. A series of screening studies involving assessment of impedance to flow in the uterine arteries have examined the potential value of Doppler in identifying pregnancies at risk of the complications of impaired placentation. Currently we are able to characterize uteroplacental perfusion with quantitative and qualitative methodologies. This review will examine both methodologies and seek to highlight conclusive and inconclusive findings.

Does sonographic determination of placental location predict fetal birth weight in diamniotic-dichorionic twins?

OBJECTIVE

The purpose of this study was to determine the association between placental location in diamniotic-dichorionic twins as determined at the time of anatomic survey and birth weight.

METHODS

We retrospectively identified all diamniotic-dichorionic twins in our Maternal-Fetal Medicine sonography database between 2000 and 2005 who had an anatomic survey, went on to be delivered at our hospital, and had records available for review (n = 304). Placental location for each twin was determined at the time of anatomic survey and grouped into both anterior or both posterior versus separate anterior and posterior. Maternal and fetal characteristics were collected from chart review. Placental pathologic findings were available for 249 (83%) patients. Outcomes analyzed were percent discordance, small size for gestational age of twin A or B, and difference in birth weight as a continuous variable. Multivariable logistic regression using stepwise backward elimination was used to adjust for potential confounders.

RESULTS

There was no difference in discordance of 20% or greater or incidence of small size for gestational age when both placentas were both anterior and both posterior compared with separate anterior and posterior: adjusted odds ratio (AdjOR), 1.38 (95% confidence interval [CI], 0.64-2.95); and AdjOR, 1.29 (95% CI, 0.57-2.89). The actual birth weight difference (A - B) was not affected by placental location (P = .36). Opposite sex fetuses and nulliparity were significantly associated with birth weight discordance: AdjOR, 2.68 (95% CI, 1.39-5.17); and AdjOR, 0.34 (95% CI, 0.28-0.94).

CONCLUSIONS

We did not find a correlation between birth weight and placental location in our cohort analysis. The presence of sex-discordant twins was associated with birth weight discordance of 20% or greater, whereas nulliparity was protective.