Fetal lung volumetry using two- and three-dimensional ultrasound

Ultrasonographic Estimation of Ventricular Volume in Infants Born Preterm with Posthemorrhagic Ventricular Dilatation: A Nested Substudy of the Randomized Controlled Early Versus Late Ventricular Intervention Study (ELVIS) Trial

OBJECTIVE

To study the potential role of ventricular volume (VV) estimation in the management of posthemorrhagic ventricular dilatation related to the need for ventriculoperitoneal (VP)-shunt insertion and 2-year neurodevelopmental outcome in infants born preterm.

STUDY DESIGN

We included 59 patients from the Early vs Late Ventricular Intervention Study from 4 participating centers. VV was manually segmented in 209 3-dimensional ultrasound scans and estimated from 2-dimensional ultrasound linear measurements in a total of 1226 ultrasounds. We studied the association of both linear measurements and VV to the need for VP shunt and 2-year neurodevelopmental outcome in the overall cohort and in the 29 infants who needed insertion of a reservoir. We used general estimating equations to account for repeated measures per individual.

RESULTS

Maximum pre-reservoir VV (β coefficient = 0.185, P = .0001) and gestational age at birth (β = -0.338; P = .0001) were related to the need for VP shunt. The estimated optimal single VV measurement cut point of 17 cm3 correctly classified 79.31% with an area under the curve of 0.76 (CI 95% 0.74-0.79). Maximum VV (β = 0.027; P = .012) together with VP shunt insertion (β = 3.773; P = .007) and gestational age (β = -0.273; P = .0001) were related to cognitive outcome at 2 years. Maximum ventricular index and anterior horn width before reservoir insertion were independently associated with the need of VP shunt and the proposed threshold groups in the Early vs Late Ventricular Intervention Study trial were associated with long-term outcome.

CONCLUSIONS

Pre-reservoir VV measurements were associated with the need for VP-shunt insertion and 2-year cognitive outcome among infants born preterm with posthemorrhagic ventricular dilatation.

TRIAL REGISTRATION

ISRCTN43171322.

Lung Volume Head Ratio: A Potential Parameter for Prediction of Respiratory Distress in Newborn

OBJECTIVE

This study aimed to evaluate the role of fetal lung biometry profile including fetal lung volume head ratio (LVHR) in predicting the occurrence of respiratory distress (RD) in early preterm newborn.

STUDY DESIGN

Prospective analytical cohort study was done to evaluate the clinical value of fetal sonographic measures, such as the total lung area (TLA), total lung volume (TLV), TLA head ratio (TLHR), LVHR, in pregnant women between 30 to 34 weeks' gestation who were expected to deliver within the next 72 hours. The cases with RD were compared with controls who had normal outcome.

RESULT

A total of 30 (27.4%) out of 110 patients, who underwent early preterm delivery, with RD rest 80 (72.6%) were controls. The TLA was 694.1 ± 373.1 mm2 in cases whereas 1,149.0 ± 506 0.7 mm2 in controls with significant difference between the two groups (p < 0.001). Similarly the lung volume (p < 0.001) and the LVHR were significantly less (p < 0.001) in cases compared with controls. The TLV was a better parameter (sensitivity, 73.7% and specificity, 86.4%) compared with TLA (sensitivity, 68.4% and specificity, 81.5%). Among the lung head ratios, LVHR had the best sensitivity of 95.5%, specificity: 80.3%, positive predictive value (PPV): 58.3%, and negative predictive value (NPV): 97.0% at the cut-off of 46.5.

CONCLUSION

RD was observed in nearly one-third of the preterm infants born between 30 and 34 weeks of gestation and could be predicted accurately in over 9 out of 10 cases using the novel parameter TLVR.

KEY POINTS

· Preterm newborn.. · Fetal lung volume.. · Respiratory distress..

Critical functional lung volumes in neonatal intensive care: evidence and clinical applications

Respiratory disease is common in premature and sick newborn infants and can often necessitate the initiation of intensive care. Newborn infants often suffer from conditions that are associated with decreased lung volumes that occur as a result of abnormal or incomplete lung development. Such conditions are prematurity and respiratory distress syndrome, preterm premature rupture of membranes and the ensuing pulmonary hypoplasia and congenital lung anomalies such as congenital diaphragmatic hernia. These diseases have a structural component manifesting with lower lung volumes and a functional component that can present with increased oxygen and ventilatory requirements. The corresponding decreased functional lung volume is possibly responsible for some unfavourable pulmonary outcomes. Some infants are unable to wean off invasive respiratory support and, in extreme cases, unable to sustain independent breathing that can lead to long-term invasive ventilation or subsequent death. The aim of this review is to summarise the available evidence behind the concept of a critical functional lung volume in neonatal intensive care and describe the clinical implications that arise from decreased functional lung volumes in the main high-risk populations of newborn infants. IMPACT: Newborn infants suffer from diseases such as respiratory distress syndrome, pulmonary hypoplasia and congenital diaphragmatic hernia that are associated with a decrease in the total lung volume and impaired lung function. Critically decreased functional lung volumes during neonatal care are associated with failure to wean off invasive respiratory support, increased mortality and possibly longer-term respiratory complications.

Assessment of the fetal lungs in utero

Antenatal diagnosis of abnormal pulmonary development has improved significantly over recent years because of progress in imaging techniques. Two-dimensional ultrasound is the mainstay of investigation of pulmonary pathology during pregnancy, providing good prognostication in conditions such as congenital diaphragmatic hernia; however, it is less validated in other high-risk groups such as those with congenital pulmonary airway malformation or preterm premature rupture of membranes. Three-dimensional assessment of lung volume and size is now possible using ultrasound or magnetic resonance imaging; however, the use of these techniques is still limited because of unpredictable fetal motion, and such tools have also been inadequately validated in high-risk populations other than those with congenital diaphragmatic hernia. The advent of advanced, functional magnetic resonance imaging techniques such as diffusion and T2* imaging, and the development of postprocessing pipelines that facilitate motion correction, have enabled not only more accurate evaluation of pulmonary size, but also assessment of tissue microstructure and perfusion. In the future, fetal magnetic resonance imaging may have an increasing role in the prognostication of pulmonary abnormalities and in monitoring current and future antenatal therapies to enhance lung development. This review aims to examine the current imaging methods available for assessment of antenatal lung development and to outline possible future directions.

Fetal Thoracic Circumference and Lung Volume and Their Relation to Fetal Size and Pulmonary Artery Blood Flow

OBJECTIVE

Research on early origins of lung disease suggests the need for studying the relationships of thoracic and lung size with fetal size and pulmonary circulation. The primary aim of this study is therefore to explore the associations between fetal thoracic circumference, lung volume, and fetal size. We also aim to assess if lung volume and thoracic circumference are associated with fetal pulmonary artery blood flow velocity measures.

METHODS

Cross-sectional assessment of singleton pregnancies from the general population (n = 447) at 30 gestational weeks (GW) was performed using ultrasound measurement of fetal thoracic circumference, lung volume, head and abdominal circumference, and femur length. We obtained Doppler blood flow velocity measures from the proximal branches of the fetal pulmonary artery. Associations between variables were studied using Pearson's correlation and multiple linear regression analyses.

RESULTS

Both thoracic circumference and lung volume correlated with fetal size measures, ranging from r = 0.64 between thoracic circumference and abdominal circumference, to r = 0.28 between lung volume and femur length. Adjustment for gestational age, maternal nicotine use, pre-pregnancy body mass index, and fetal sex marginally influenced the associations with abdominal circumference. The correlations of thoracic circumference and lung volume with pulmonary artery blood flow velocity measures were weak (r ≤ 0.17).

CONCLUSION

We found moderate to low correlation between thoracic circumference, lung volume, and fetal size at 30 GW. The closest relationship was with the abdominal circumference. We found low correlations of thoracic circumference and lung volume with pulmonary artery blood flow velocity measures.

Prenatal Ultrasound Markers: A Comparative Study for Prediction of Respiratory Distress in Early Preterm Newborns

Purpose of Study

This study aimed to compare the prenatal ultrasound parameters- fetal lung biometry and pulmonary artery Doppler in preterm newborns for prediction of respiratory distress (RD).

Methods

A prospective analytic study was conducted in Department of Obstetrics and Gynecology in collaboration with Department of Neonatalogy. Fetal ultrasound and Doppler parameters were evaluated in women predisposed to have preterm delivery at or before 34 weeks. The neonates were followed for occurrence of RD.

Result

Out of 100 study population, neonates who developed RD were taken as cases (n = 36) and rest were grouped as controls (n = 64). The gestational age at delivery, mean birth weight and Apgar score were significantly less in cases than controls. All the fetal lung biometric parameters were significantly less in cases than controls (p value < 0.001). The fetal lung volume had highest sensitivity (72.22%) and negative predictive value (83%). The right lung area had highest specificity (89%) and positive predictive value (72%). Among the Doppler parameters, the At/Et ratio showed high degree of accuracy (68%). The sensitivity and specificity were 55.56% and 75%, respectively. The positive and negative predictive values were 72% and 60%, respectively.

Conclusions

Both fetal lung biometry and pulmonary artery Doppler offer an excellent noninvasive approach for assessment of fetal lung maturity, clinically assessed by RD. On comparison of all the ultrasound parameters, fetal lung volume and At/Et ratio showed highest degree of accuracy in prediction of RD.

Antenatal management and outcomes of pregnancies with congenital diaphragmatic hernia

BACKGROUND

The objective of this study is to evaluate the obstetric outcomes of pregnancies with congenital diaphragmatic hernia (CDH).

METHODS

Fifty one pregnancies prenatally diagnosed with CDH at our institution between January 1, 2002 and August 31, 2018 were retrospectively evaluated. The pregnancies were divided into two groups according to neonatal survival. Demographic features, clinical characteristics and prognostic factors were compared between the neonatal survival (n = 16) and non-survival (n = 28) groups. Cut-off values of fetal lung area to head circumference ratio (LHR), observed/expected LHR (o/e LHR) and observed/expected total fetal lung volume (o/e TFLV) for neonatal survival were calculated.

RESULTS

Thirty six (70.6%) and fifteen (29.4%) fetuses had left and right sided CDH respectively. Seven patients chose termination of their pregnancies (13.7%). Statistically significant differences were found between survival and non-survival groups in terms of parity, median gestational week at diagnosis, polyhydroamniosis rate, CDH type, stomach position, liver position, median LHR, o/e LHR, o/e TFLV, median 5th minute Apgar score and neonatal operation rate values (p values were 0.03,<0.001, 0.02, 0.006,<0.001, 0.006,<0.001,<0.001,<0.001, 0.04 and <0.001 respectively). According to ROC curve analysis, 1.05 (82% sensitivity, 74% specificity) for LHR, 22.5 (78.6% sensitivity, 73.9% specifity) for o/e LHR and 23.5 (85.7% sensitivity,74.2% specificity) for o/e TFLV were determined to be cut-offs for neonatal survival, respectively, with highest sensitivity and specificity.

CONCLUSION

Earlier gestational week at diagnosis, right sided CDH, presence of liver herniation, supradiaphragmatic stomach position, lower LHR, o/e LHR and o/e TFLV were associated with decreased rates of neonatal survival.

IntraVoxel Incoherent Motion (IVIM) MRI of fetal lung and kidney: Can the perfusion fraction be a marker of normal pulmonary and renal maturation?

PURPOSE

To investigate the use of IntraVoxel Incoherent Motion (IVIM) MRI in the study of microstructural tissue changes occurring in fetal lung and kidney during gestation.

METHODS

34 normal pregnancies were enrolled. Patients were divided into two groups based on gestational age (GA): group A (21-29 weeks) and group B (30-39 weeks). MR examinations were performed at 1.5T, with a standard fetal MR protocol including a Diffusion-Weighted Echo-Planar Imaging sequence with 10 different b-values (0, 10, 30, 50, 75, 100, 200, 400, 700, 1000s/mm²). For each fetus, two bilateral ROIs were manually placed in lung and renal parenchyma. Mean values of perfusion fraction f, pseudo-diffusion coefficient D* and diffusion coefficient D were obtained. The correlation between IVIM parameters and GA was investigated.

RESULTS

In renal ROIs a positive correlation between f_kidney and GA (p < 0.005) was found; similarly f_lung showed a statistically significant correlation with GA (p < 0.001). F mean values were significantly higher in group B compared to group A in both renal (p = 0.0002) and lung (p = 0.018) ROIs. No correlation was found in D and D* as a function of GA.

CONCLUSIONS

The IVIM perfusion fraction f may be considered as a potential marker of pulmonary and renal maturation in relation to hemodynamic changes described in intrauterine life. Our results highlight that IVIM model is useful as an additional prenatal diagnostic tool to study lung and renal development.

Reference range of fetal thorax using two-dimensional and three-dimensional ultrasound VOCAL technique and application in fetal thoracic malformations

Background

To establish the normal reference range of fetal thorax by two-dimensional (2D) and three-dimensional (3D) ultrasound VOCAL technique and evaluate the application in diagnosing fetal thoracic malformations.

Methods

A prospective cross-sectional study was undertaken involving 1077 women who have a normal singleton pregnancy at 13–40 weeks gestational age (GA). 2D ultrasound and 3D ultrasound VOCAL technique were utilized to assess fetal thoracic transverse diameter, thoracic anteroposterior diameter, thoracic circumference, thoracic area, lung volume, thoracic volume and lung-to-thoracic volume ratio. The nomograms of 2D and 3D fetal thoracic measurements were created to GA. 50 cases were randomly selected to calculate intra- and inter-observer reliability and agreement. In addition, the case groups including congenital skeletal dysplasia (SD) (15), congenital diaphragmatic hernia (CDH) (30), pulmonary sequestration (PS) (25) and congenital cystic adenomatoid malformation (CCAM) (36) were assessed by the nomograms and followed up subsequently.

Results

Both 2D and 3D fetal thoracic parameters increased with GA using a quadratic regression equation. The intra- and inter-observer reliability and agreement of each thoracic parameter were excellent. 2D fetal thoracic parameters could initially evaluate the fetal thoracic development and diagnose the skeletal thoracic deformity, and lung volume, thoracic volume and lung-to-thorax volume ratio were practical to diagnose and differentiate CDH, PS and CCAM.

Conclusion

We have established the normal fetal thoracic reference range at 13–40 weeks, which has a high value in diagnosing congenital thoracic malformations.

Fetal Physiologically Based Pharmacokinetic Models: Systems Information on the Growth and Composition of Fetal Organs

BACKGROUND

The growth of fetal organs is a dynamic process involving considerable changes in the anatomical and physiological parameters that can alter fetal exposure to xenobiotics in utero. Physiologically based pharmacokinetic models can be used to predict the fetal exposure as time-varying parameters can easily be incorporated.

OBJECTIVE

The objective of this study was to collate, analyse and integrate the available time-varying parameters needed for the physiologically based pharmacokinetic modelling of xenobiotic kinetics in a fetal population.

METHODS

We performed a comprehensive literature search on the physiological development of fetal organs. Data were carefully assessed, integrated and a meta-analysis was performed to establish growth trends with fetal age and weight. Algorithms and models were generated to describe the growth of these parameter values as functions of age and/or weight.

RESULTS

Fetal physiologically based pharmacokinetic parameters, including the size of the heart, liver, brain, kidneys, lungs, spleen, muscles, pancreas, skin, bones, adrenal and thyroid glands, thymus, gut and gonads were quantified as a function of fetal age and weight. Variability around the means of these parameters at different fetal ages was also reported. The growth of the investigated parameters was not consistent (with respect to direction and monotonicity).

CONCLUSION

Despite the limitations identified in the availability of some values, the data presented in this article provide a unique resource for age-dependent organ size and composition parameters needed for fetal physiologically based pharmacokinetic modelling. This will facilitate the application of physiologically based pharmacokinetic models during drug development and in the risk assessment of environmental chemicals and following maternally administered drugs or unintended exposure to environmental toxicants in this population.

Fetal arthrogryposis multiplex congenita/fetal akinesia deformation sequence (FADS)-Aetiology, diagnosis, and management

Arthrogryposis multiplex congenita (AMC) refers to an aetiologically heterogenous condition, which consists of joint contractures affecting two or more joints starting prenatally. The incidence is approximately one in 3000 live births; however, the prenatal incidence is higher, indicating a high intrauterine mortality. Over 320 genes have been implicated showing the genetic heterogeneity of the condition. AMC can be of extrinsic aetiology resulting from intrauterine crowding secondary to congenital structural uterine abnormalities (eg, bicornuate or septate uterus), uterine tumors (eg, fibroid), or multifetal pregnancy or intrinsic/primary/fetal aetiology, due to functional abnormalities in the brain, spinal cord, peripheral nerves, neuromuscular junction, muscles, bones, restrictive dermopathies, tendons and joints. Unlike many of the intrinsic/primary/fetal causes which are difficult to treat, secondary AMC can be treated by physiotherapy with good response. Primary cases may present prenatally with fetal akinesia associated with joint contractures and occasionally brain abnormalities, decreased muscle bulk, polyhydramnios, and nonvertex presentation while the secondary cases usually present with isolated contractures. Complete prenatal and postnatal investigations are needed to identify an underlying aetiology and provide information regarding its prognosis and inheritance, which is critical for the obstetrical care providers and families to optimize the pregnancy management and address future reproductive plans.

Fetal Anthropometric Features: A Postmortem Study of Fetuses After the Termination of Pregnancy for Psychosocial Reasons Between 12 and 20 Gestational Weeks

INTRODUCTION

Reference ranges in fetal postmortem anthropometric data derive from heterogeneous studies and rely on data obtained after intrauterine fetal death and abortion, which may introduce bias in the reported fetal growth parameters. We report anthropometric findings in fetuses with the least variation due to cause of death or developmental anomalies.

METHODS

We analyzed fetuses after the termination of pregnancy for psychosocial reasons. The external measurements, X-ray dimensions, and body and organ weights were recorded as well as the placenta weight. A thorough and standardized postmortem analysis allowed the design of 2 different groups. Group 1 was composed of fetuses (1) born to mothers with no relevant obstetrical history, (2) no X-ray anomaly, (3) no abnormal autopsy findings, and (4) unremarkable placenta histology. An anomaly in any of these 4 entities moved the fetuses to Group 2. For reference ranges and graph construction, a well-designed statistical methodology was applied.

RESULTS

A total of 335 fetuses were analyzed during an 11-year period. Group 1 comprised 232 fetuses aged 12 to 20 gestational weeks, whereas 103 fetuses were considered in Group 2. Comparison between the 2 groups showed almost no differences. Only the Group 1 results were submitted to statistical analysis, and reference ranges and graphs were constructed.

CONCLUSIONS

To the best of our knowledge, we provide in this study the first anthropometric references established from almost normal fetuses, albeit for a limited fetal timeframe.

Transrectal three-dimensional fetal volumetry and crown-rump length measurement during early gestation in mares: Intra- and inter-observer reliability and agreement

The aim of this study was to investigate if transrectal three-dimensional (3D) ultrasound is a reliable technique to measure equine fetal volume (FV) during early gestation in mares. In total 149 warmblood mares were examined once transrectally on days 45 ± 1 of pregnancy with a portable 3D ultrasound device (Voluson^® i, GE Healthcare, Zipf, Austria). The following measurements were performed: Two-dimensional (2D) and 3D crown-rump length (CRL), FV using Virtual Organ Computer-aided AnaLysis (VOCAL™) software with rotational angles of 6° and 30°. To analyze intra- and inter-observer reliability (intraclass correlation coefficient (ICC)) and agreement (Bland-Altman's limits of agreement (LoA)) of FV measurements, images from 60 horse fetuses were selected and repeatedly analyzed by the same examiner (A) and by a second examiner (B). The time for each ultrasound examination (2D and 3D) and for the FV measurements was recorded. The 3D measured CRL was larger (P < 0.001) than the 2D CRL. Repeated measurements of 3D CRL showed a higher reliability (ICC = 0.91 (0.88-0.94), P < 0.001) and agreement (mean = 0.13%, 95% LoA: 7.45 to +7.19) compared to reliability (ICC = 0.50 (0.36-0.61), P < 0.001) and agreement (mean = -1.54%, 95% LoA: 23.29 to +20.21) of the CRL measurement in 2D mode. For intra-observer examinations, reliability was highest when using a rotational angle of 30° (ICC = 0.98 (0.97-0.99), P < 0.001). The inter-observer reliability of 3D measurements was good (ICC = 0.85 (0.67-0.92), P < 0.001). The extra time needed to perform the 3D scan ranged from 1 to 9 min and FV measurements lasted 03:30 ± 00:46 and 08:10 ± 01:05, for rotational angles of 30° and 6°, respectively. In conclusion, this study showed a high level of intra- and inter-observer reliability and agreement for FV measurements using VOCAL™. Furthermore, the 6° and 30° rotational angles can be used interchangeably, but test duration, reliability and agreement were better with the 30° rotational step method. The CRL measurements obtained with 3D mode probably reflects the true CRL, compared to the 2D measured CRL.

Fetal Lung Volumes by MRI: Normal Weekly Values From 18 Through 38 Weeks' Gestation

OBJECTIVE

The purpose of this study is to establish normal total fetal lung volume reference ranges from 18 to 38 weeks' gestation at 1-week intervals.

MATERIALS AND METHODS

A retrospective analysis of 665 patients who underwent fetal MRI at two tertiary fetal centers from 2001 to 2013 was performed. Total fetal lung volume was measured in at least two planes, either manually or using a 3D workstation. The mean, median, SD, minimum, maximum, and lower and upper quartiles for total fetal lung volume were determined per gestational week. A t test was used to compare our values to previously reported values. A new formula to calculate total fetal lung volume derived from our data was created using a regression model. Comparisons between total fetal lung volume obtained by different imaging planes and manual versus semiautomatic calculation were also performed.

RESULTS

The mean normal total fetal lung volume showed a weekly increase from 18 through 35 weeks' gestation. Means were compared with the expected total fetal lung volume generated by the Rypens formula, showing statistically significant lower mean total fetal lung volume from week 19 to week 22 (p < 0.05). Comparison between our data-derived total fetal lung volume formula and the Rypens formula showed very similar values at every gestational age. No difference in total fetal lung volume was seen when comparing imaging planes or manual versus semiautomatic methods.

CONCLUSION

Measured mean total fetal lung volume values at 19-22 weeks are significantly lower than those predicted by the Rypens formula. Therefore, we propose preferential use of our values for prenatal counseling and delivery planning.

Qualitative and quantitative ultrasound attributes of maternal-foetal structures in pregnant ewes

The aim of this study was to examine foetal organs and placental tissue to establish a correlation between the changes in the composition of these structures associated with their maturation and the ultrasonographic characteristics of the images. Twenty-four pregnant ewes were included in the study. Ultrasonography assessments were performed in B-mode, from the ninth gestational week until parturition. The lungs, liver and kidneys of foetuses and placentomes were located in transverse and longitudinal sections to evaluate the echogenicity (hypoechoic, isoechoic, hyperechoic or mixed) and echotexture (homogeneous and heterogeneous) of the tissues of interest. For quantitative evaluation of the ultrasonographic characteristics, it was performed a computerized image analysis using a commercial software (Image ProPlus^® ). Mean numerical pixel values (NPVs), pixel heterogeneity (standard deviation of NPVs) and minimum and maximum pixel values were measured by selecting five circular regions of interest in each assessed tissue. All evaluated tissues presented significant variations in the NPVs, except for the liver. Pulmonary NPVmean, NPVmin and NPVmax decreased gradually through gestational weeks. The renal parameters gradually decreased with the advancement of the gestational weeks until the 17th week and later stabilized. The placentome NPVmean, NPVmin and NPVmax decreased gradually over the course of weeks. The hepatic tissue did not show echogenicity and echotexture variations and presented medium echogenicity and homogeneous echotexture throughout the experimental period. It was concluded that pixels numerical evaluation of maternal-foetal tissues was applicable and allowed the identification of quantitative ultrasonographic characteristics showing changes in echogenicity related to gestational age.

Prognosis of isolated congenital diaphragmatic hernia using lung-area-to-head-circumference ratio: variability across centers in a national perinatal network

OBJECTIVE

Congenital diaphragmatic hernia (CDH) is a severe anomaly. The observed-to-expected lung-area-to-head-circumference ratio (o/e-LHR) has been shown to provide a useful prediction of subsequent survival of fetuses with CDH in referral centers with expertise and a large caseload. However, the accuracy of o/e-LHR measurements in general fetal medicine units with less expertise is not well known. The aim of this study was to evaluate the capacity of o/e-LHR to provide a useful prediction of mortality of fetuses with CDH when the measurement is performed in fetal medicine units with different levels of expertise.

METHODS

Between January 2008 and November 2013, 305 live births with expectantly managed left-sided isolated CDH were recorded in the database of the French National Center for Rare Diseases (31 centers) and followed up after birth. Centers were grouped into two categories according to their mean annual CDH caseload over the study period: large centers with an average of ≥ 14 cases and smaller centers with < 14 cases per year. The relationship between o/e-LHR and 28-day and 6-month mortality was modeled using fractional polynomials and the predictive value of o/e-LHR was quantified using the area under the receiver-operating characteristics curve. Comparisons between the two center categories were carried out. Analyses were adjusted for potential confounders such as thoracic herniation of the liver and gestational age at birth and at diagnosis.

RESULTS

During the study period, two large centers managed a total of 82 CDH cases and 29 smaller centers a total of 223 CDH cases. Overall, there was a significant inverse relationship between 28-day mortality rate and o/e-LHR, which decreased from 54% when o/e-LHR was 20% to 6% when o/e-LHR was 75% (P < 0.01). When the category of center was considered, adjusted associations between o/e-LHR and 28-day mortality were significantly different (P = 0.032) between large and smaller centers. The ability to predict survival at 28 days postpartum based on o/e-LHR was better in large centers; for a specificity of 0.30, the sensitivity was 0.71 in large centers and 0.55 in smaller ones. The results were similar for 6-month mortality.

CONCLUSIONS

Our results show that o/e-LHR measured on two-dimensional ultrasound is a good indicator of neonatal prognosis in cases of CDH that may be used even in fetal medicine centers with a small caseload. However, our results also suggest that LHR measurement may be difficult to perform correctly. Therefore, appropriate training should be offered to professionals. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Human fetal lung morphometry at autopsy with new modeling to quantitate structural maturity

OBJECTIVES

To demonstrate a simplified morphometric procedure, including a new model for acinar structural maturity, applicable to autopsy fetal lung and present reference values for these parameters.

STUDY DESIGN

Cases with autopsy consent for research were studied. To simplify analysis only critical morphometric parameters were measured to allow calculation of gas-exchange surface area.

SUBJECT SELECTION

A total of 58 fetuses, 16-40 weeks were included. Subjects were rejected with any condition predisposing to pulmonary hypo/hyperplasia, significant maceration, or if lung weight/bodyweight or microscopy identified pulmonary hypoplasia or lung growth disorders.

METHODOLOGY

Lungs were inflation fixed, weights and volumes determined, sampled, then returned to the body. Volume densities (V_V ) of parenchyma/non-parenchyma and air-space/gas-exchange tissue, gas-exchange surface density (S_V ), and total surface area (SA) were determined. The number, mean radius, and septal thickness of modeled airspace-spheres were calculated. Equations were generated for each parameter function of gestation and bodyweight.

RESULTS

From 16 to 40-week weights and volumes increased as power functions from ∼4 g/mL to ∼90 g/mL. Parenchyma/non-parenchyma changed little-75:25 (16 weeks) to 71:29 (term). Parenchyma was 10% airspace:90% tissue early and 50:50 by term. Gas-exchange S_V increased from 175 to 450 cm² /cm³ and total SA increased from 0.059 to 4.793 m² . There were 3.31 × 10⁶ airspace-spheres, 12 µ radius, septal thickness 30 µ at 16 weeks, increasing to 56.92 × 10⁶ , 26 µ radius, septal thickness 13 µ by term.

CONCLUSIONS

Morphometry can feasibly be performed at autopsy, providing more informative quantitative data on lung structural development than current methods utilized. This reference data set compares well with published data.

Ultrasound lineal measurements predict ventricular volume in posthaemorrhagic ventricular dilatation in preterm infants

AIM

Posthaemorrhagic ventricular dilatation (PHVD) is monitored by conventional two-dimensional ultrasound (2DUS). The aims of this study were to determine the volume of the lateral ventricles using three-dimensional ultrasound (3DUS) in preterm infants with PHVD and to evaluate the relationship between volume and linear measurements.

METHODS

Serial 2DUSs and 3DUSs were performed on preterm infants with PHVD admitted to the neonatal intensive care unit at Puerta del Mar Hospital, Cádiz, Spain, from January 2013 to December 2014. The ventricular index, anterior horn width and thalamo-occipital distance were used as ventricular lineal measurements. Ventricular volume was calculated offline.

RESULTS

Serial ultrasounds from seven preterm infants were measured. Each linear measurement was significantly associated with volume, and an equation was obtained through a significant multilevel mixed-effects lineal regression model: ventricular volume (cm³ ) = -11.02 + 0.668*VI + 0.817*AHW + 0.256*TOD. Intra-observer and interobserver agreement was excellent with an intraclass correlation coefficient of 0.99.

CONCLUSION

Lateral ventricular volumes of preterm infants with PHVD could be reliably determined using 3DUS. Ventricular volume could be accurately estimated using three lineal measurements. More studies are needed to address the importance of volume determination in PHVD.

Prenatal assessment of pulmonary maturity on 3-D ultrasound

AIM

The aim of this study was to assess the feasibility and accuracy of 3-D ultrasound indices to evaluate fetal lung maturity, and to establish a normal reference for fetal lung volume (FLV) and fetal lung-to-liver intensity ratio (FLLIR) in a Chinese population.

METHODS

A total of 1022 pregnant women with singleton pregnancy were prospectively studied between June 2008 to June 2011. Ultrasound examination was performed. The breathing-related nasal fluid flow (BRNFF) spectrum, FLV, pulmonary artery blood flow parameters, and echo intensity of the lung were calculated. Phosphoglycerides in the amniotic fluid were measured on thin layer chromatography.

RESULTS

FLLIR and FLV were positively and linearly correlated with gestational age (F = 0.915, 0.846). Indicators of fetal lung maturity included FLLIR >1.1, FLV >50 mL, and regular BRNFF spectrum, with positive likelihood ratios of 12.28, 11.78, and 11.63, independently.

CONCLUSION

Ultrasound indices, including FLLIR, FLV and BRNFF may serve as useful alternatives to amniotic fluid phospholipids in analyzing fetal lung maturity in Chinese patients.

Quantitative Anatomy of the Growing Lungs in the Human Fetus

Using anatomical, digital, and statistical methods we examined the three-dimensional growth of the lungs in 67 human fetuses aged 16-25 weeks. The lung dimensions revealed no sex differences. The transverse and sagittal diameters and the base circumference were greater in the right lungs while the lengths of anterior and posterior margins and the lung height were greater in the left lungs. The best-fit curves for all the lung parameters were natural logarithmic models. The transverse-to-sagittal diameter ratio remained stable and averaged 0.56 ± 0.08 and 0.52 ± 0.08 for the right and left lungs, respectively. For the right and left lungs, the transverse diameter-to-height ratio significantly increased from 0.74 ± 0.09 to 0.92 ± 0.08 and from 0.56 ± 0.07 to 0.79 ± 0.09, respectively. The sagittal diameter-to-height ratio significantly increased from 1.41 ± 0.23 to 1.66 ± 0.18 in the right lung, and from 1.27 ± 0.17 to 1.48 ± 0.22 in the left lung. In the fetal lungs, their proportionate increase in transverse and sagittal diameters considerably accelerates with relation to the lung height. The lung dimensions in the fetus are relevant in the evaluation of the normative pulmonary growth and the diagnosis of pulmonary hypoplasia.

Prediction of lethal pulmonary hypoplasia by means fetal lung volume in skeletal dysplasias: a three-dimensional ultrasound assessment

OBJECTIVE

The aim of this study was to assess the capacity of three-dimensional ultrasound (3DUS) for predicting lethality in fetuses with skeletal dysplasia.

METHODS

Twenty-four fetuses between 20 and 32 weeks of gestation were assessed. Bilateral lung volume scans were performed three times in each fetus during one ultrasound session. The virtual organ computer-aided analysis method was used to obtain a sequence of six sections of each lung around a fixed axis, and a rotation angle of 30° was adopted. Fetal lung volume measurements were analyzed according to the reference range. After birth, lung hypoplasia was diagnosed considering clinical and radiological criteria.

RESULTS

Of all cases of skeletal dysplasia, 18 (75%) were lethal. Among the lethal cases, after postnatal diagnosis, four were osteogenesis imperfecta type II, three were thanatophoric dysplasia and two were campomelic dysplasia. The remaining nine cases remained without a definitive diagnosis. The accuracy of 3DUS in predicting lethality in fetuses with skeletal dysplasia was high, with a sensitivity of 83.3%, specificity of 100%, positive predictive value of 100% and negative predictive value of 66.7%. The kappa index of 0.174 showed a good agreement between the possibility of lethality when the 3DUS volume measurement was altered and real lethality after birth (p < 0.001).

CONCLUSION

This study suggests that the 3DUS lung volume measurement is a good predictor of lethal pulmonary hypoplasia in fetuses with skeletal dysplasia, with high accuracy.

Volumetric growth of the lungs in human fetuses: an anatomical, hydrostatic and statistical study

Purpose

The prenatal assessment of lung volume is becoming increasingly important in determining survival in both preterm infants and newborns affected by pulmonary hypoplasia. This study aimed to examine the lung volumes in the human fetus at varying gestational ages.

Materials and methods

Using anatomical, hydrostatic (water displacement according to Archimedes’ patent) and statistical methods (one-way ANOVA test for paired data and post-hoc Bonferroni test, Kolmogorov–Smirnov test, Levene’s test, Student’s t test, regression analysis), volumes of the right and left lungs were measured in 67 human fetuses of both sexes (35 males, 32 females) aged 16–25 weeks, derived from spontaneous abortions and stillbirths.

Results

No male–female differences concerning the right and left pulmonary volumes were found. The mean volume of the right lung increased from 1.43 ± 0.25 to 8.45 ± 2.66 cm³, according to the cubic function y = –1.592 + 0.0007 × age³ ± 0.851 (R² = 0.84). The volumetric growth of the left lung, from 1.24 ± 0.22 to 6.78 ± 3.03 cm³, followed the cubic model y = –1.110 + 0.0005 × age³ ± 0.794 (R² = 0.78). The total pulmonary volume increased from 2.67 ± 0.47 to 15.22 ± 5.58 cm³, in accordance with the cubic model y = –2.729 + 0.0012 × age³ ± 1.598 (R² = 0.83). The mean volumes of the right and left lungs accounted for 54.9 ± 2.0 and 45.1 ± 2.0 %, respectively, of the total lung volume.

Conclusions

No sex differences are found between the lung volumes in the fetus. The growth of fetal lung volume follows a three-degree polynomial function. Throughout the analyzed period the two lungs grow proportionately to each other, with the volumetric predominance of the right lung. The lung volumes in the fetus are of great relevance in the evaluation of the normal pulmonary growth and the diagnosis of pulmonary hypoplasia.

Motion corrected 3D reconstruction of the fetal thorax from prenatal MRI

In this paper we present a semi-automatic method for analysis of the fetal thorax in genuine three-dimensional volumes. After one initial click we localize the spine and accurately determine the volume of the fetal lung from high resolution volumetric images reconstructed from motion corrupted prenatal Magnetic Resonance Imaging (MRI). We compare the current state-of-the-art method of segmenting the lung in a slice-by-slice manner with the most recent multi-scan reconstruction methods. We use fast rotation invariant spherical harmonics image descriptors with Classification Forest ensemble learning methods to extract the spinal cord and show an efficient way to generate a segmentation prior for the fetal lung from this information for two different MRI field strengths. The spinal cord can be segmented with a DICE coefficient of 0.89 and the automatic lung segmentation has been evaluated with a DICE coefficient of 0.87. We evaluate our method on 29 fetuses with a gestational age (GA) between 20 and 38 weeks and show that our computed segmentations and the manual ground truth correlate well with the recorded values in literature.

Prediction of mortality and the need for neonatal extracorporeal membrane oxygenation therapy by 3-dimensional sonography and magnetic resonance imaging in fetuses with congenital diaphragmatic hernias

OBJECTIVES

To compare different rotation angles for assessment of fetal lung volume by 3-dimensional (3D) sonography with magnetic resonance imaging (MRI) regarding prediction of mortality and the need for neonatal extracorporeal membrane oxygenation (ECMO) therapy in fetuses with congenital diaphragmatic hernias.

METHODS

One hundred patients with fetal congenital diaphragmatic hernias between 22 and 39 weeks' gestation were examined by 3D sonography and MRI. Sonographic contralateral fetal lung volumes were assessed by the rotational technique (virtual organ computer-aided analysis) at 3 different rotation angles: 6°, 15°, and 30°. The MRI fetal lung volumes were calculated based on multiplanar T2-weighted MRI. To eliminate the influence of gestational age, the observed to expected contralateral fetal lung volume on sonography and the observed to expected fetal lung volume on MRI were calculated. Receiver operating characteristic (ROC) curves were calculated for the statistical prediction of survival and need for ECMO therapy by the observed to expected contralateral fetal lung volume (sonography) and observed to expected fetal lung volume (MRI).

RESULTS

One hundred cases were assessed for survival and 89 for ECMO necessity (11 neonates were not eligible for ECMO). For prediction of postpartum survival and ECMO necessity, the areas under the ROC curves (AUCs) showed very similar results for MRI and 3D sonography: observed to expected fetal lung volume by MRI, 0.819 (95% confidence interval, 0.730-0.909) and 0.835 (0.748-0.922), respectively; 6° sonography, 0.765 (0.647-0.883) and 0.820 (0.734-0.905); 15° sonography, 0.784 (0.672-0.896) and 0.811 (0.719-0.903); and 30° sonography, 0.732 (0.609-0.855) and 0.772 (0.671-0.872). Comparisons between the AUCs revealed no statistical differences.

CONCLUSIONS

We have shown the good prognostic value of 3D sonography in fetuses with congenital diaphragmatic hernias compared with MRI, particularly when using small rotation angles. Therefore, it can be an appropriate diagnostic tool when counseling patients for congenital diaphragmatic hernias.

Prenatal diagnosis and pathology of laryngeal atresia in congenital high airway obstruction syndrome

Congenital high airway obstruction syndrome is a rare but life-threatening condition. Therefore, prenatal diagnosis is important. The obstruction can be due to laryngeal/tracheal atresia or external compression. While a differential diagnosis with congenital cystic adenomatoid malformation (CCAM) type III may be difficult, it is still possible with ultrasonography. In this study, we report a case of bilateral echogenic lungs with hydrops fetalis. After the prenatal diagnosis of laryngeal atresia, the couple opted to have an elective termination of pregnancy performed at 20 weeks of gestation. The diagnosis was confirmed by a complete pathological examination.

Three-dimensional ultrasonographic assessment of fetal total lung volume as a prognostic factor in primary pleural effusion

OBJECTIVES

The purpose of this study was to predict perinatal outcomes using fetal total lung volumes assessed by 3-dimensional ultrasonography (3DUS) in primary pleural effusion.

METHODS

Between July 2005 and July 2010, total lung volumes were prospectively estimated in fetuses with primary pleural effusion by 3DUS using virtual organ computer-aided analysis software. The first and last US examinations were considered in the analysis. The observed/expected total lung volumes were calculated. Main outcomes were perinatal death (up to 28 days of life) and respiratory morbidity (orotracheal intubation with mechanical respiratory support >48 hours).

RESULTS

Twelve of 19 fetuses (63.2%) survived. Among the survivors, 7 (58.3%) had severe respiratory morbidity. The observed/expected total lung volume at the last US examination before birth was significantly associated with perinatal death (P < .01) and respiratory morbidity (P < .01) as well as fetal hydrops (P < .01) and bilateral effusion (P = .01).

CONCLUSIONS

Fetal total lung volumes may be useful for the prediction of perinatal outcomes in primary pleural effusion.

New anatomical landmarks to study the relationship between fetal lung area and thoracic circumference by three-dimensional ultrasonography

OBJECTIVE

To evaluate the relation between total lung area (TLA) and thoracic circumference (TC) ratio by three-dimensional (3D) ultrasonography applying new anatomical landmarks as the fetal aorta and inferior angle of the scapula.

METHODS

A longitudinal prospective study was conducted with 56 uncomplicated pregnancies between 24 and 32 weeks of gestation. Polynomial regressions were used to evaluate the correlation between TC and gestational age (GA) as well as TC and estimated fetal weight (EFW). A simple linear regression was used to evaluate the correlation between TLA and Total thoracic area (TTA) and GA. The intraclass correlation coefficient (ICC) was used to assess the intra and interobserver variability.

RESULTS

127 examinations were performed. TC values ranged from 150 to 174 mm (mean 166 mm) at 24 weeks and 215-248 mm (mean 231 mm) at 32 weeks. The TLA/TC ratio ranged from a mean of 0.64 at 24 weeks (range 0.56-0.70) to 0.90 at 32 weeks gestation (range 0.79-1.01). The intraobserver variability using the ICC was of 0.919 for TC; 0.916 for TTA; 0.860 for right lung area (RLA) and 0.910 for left lung area (LLA). Interobserver reproducibility was with an ICC of 0.970 for TC; 0.984 for RLA and 0.910 for LLA.

CONCLUSIONS

Measurement of fetal TC and the relationship between TLA and TC by 3D-ultrasonography applying new anatomical landmarks shows good reproducibility and allows a new assessment of thoracic and lung growth.

A review of fetal volumetry: the need for standardization and definitions in measurement methodology

Volume charts of fetal organs and structures vary considerably among studies. This review identified 42 studies reporting normal volumes, namely for fetal brain (n = 3), cerebellum (n = 4), liver (n = 6), femur (n = 2), lungs (n = 15), kidneys (n = 3) and first-trimester embryo (n = 9). The differences among median volumes were expressed both in percentage form and as standard deviation scores. Wide discrepancies in reported normal volumes make it extremely difficult to diagnose pathological organ growth reliably. Given its magnitude, this variation is likely to be due to inconsistencies in volumetric methodology, rather than population differences. Complicating factors include the absence of clearly defined anatomical landmarks for measurement; inadequate assessment and reporting of method repeatability; the inherent difficulty in validating fetal measurements in vivo against a reference standard; and a multitude of mutually incompatible three-dimensional (3D) imaging formats and software measuring tools. An attempt to standardize these factors would improve intra- and inter-researcher agreement concerning reported volumetric measures, would allow generalization of reference data across different populations and different ultrasound systems, and would allow quality assurance in 3D fetal biometry. Failure to ensure a quality control process may hamper the wide use of 3D ultrasound.

Assessment of lung volume by 3-dimensional sonography and magnetic resonance imaging in fetuses with congenital diaphragmatic hernias

OBJECTIVES

The purpose of this study was to evaluate the influence of different rotation angles in assessment of the contralateral lung volume by 3-dimensional (3D) sonography in comparison to magnetic resonance imaging (MRI) in fetuses with congenital diaphragmatic hernias.

METHODS

A total of 126 measurements by 3D sonography and MRI were conducted in 81 patients between 18 and 39 weeks' gestation. The 3D sonographic volumes of the contralateral fetal lung were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6°, 15°, and 30°. Transverse multiplanar T2-weighted MRI was performed for the MRI measurements. To compare the accuracy of 3D sonographic volumetry using different rotation angles, MRI assessment was taken as the reference method, and percentage errors and limits of agreement were calculated for each angle.

RESULTS

Three-dimensional sonographic volume measurements showed a high correlation with MRI (6° angle, R(2) = 0.86; 15° angle, R(2) = 0.78; 30° angle, R(2) = 0.68). The mean percentage error showed no systematic error. With regard to random error, the 6° step had significantly lower values than the larger angles 30° step (R = 0.472) and the narrowest limits of agreement.

CONCLUSIONS

Especially when using a small rotation angle, assessment of the contralateral fetal lung volume by 3D sonography in congenital diaphragmatic hernias is a reliable alternative to MRI.

Inter- and intra-observer variation of fetal volume measurements with three-dimensional ultrasound in the first trimester of pregnancy

OBJECTIVES

To determine the inter- and intra-observer variation of volume calculations of human fetuses at a gestational age of 11(+0)-13(+6) weeks by three-dimensional ultrasound (3DUS).

METHODS

3DUS datasets were acquired during nuchal translucency measurements. The fetal volume (FV) was measured in 65 cases by two independent investigators. The Virtual Organ Computer aided AnaLysis (VOCAL™) imaging software was used to manually calculate the FV (rotational angle 9°). Inter- and intra-observer variation were assessed by Bland-Altman plots and intraclass correlation coefficients (ICC).

RESULTS

Both inter- and intraobserver reproducibility were highly reliable as shown by the Bland-Altman plots and an ICC of respectively 0.934 and 0.994.

CONCLUSION

FV calculation by 3DUS with VOCAL and a rotational angle of 9° is feasible and has a high inter- and intraobserver reliability in the first trimester of pregnancy.

In vitro models of the fetal lung: comparison of lung volume measurements with 3-dimensional sonography and magnetic resonance imaging

OBJECTIVES

Three-dimensional (3D) sonography is an established volumetric method in gynecology and obstetrics. The aim of this study was to investigate the variability of 3D sonographic measurements and their accuracy in comparison with magnetic resonance imaging (MRI) for assessing fetal lung volume using in vitro lung models.

METHODS

Twenty-three in vitro lung models with randomly defined volumes ranging from 1 to 60 mL were made from gelatin with plastic sheaths, manually molded into the shape of fetal lungs. The models were measured using 3D sonography and MRI. The 3D sonographic volumes were calculated using the rotational technique with angles of 6° and 30°. Multiplanar T2-weighted sequences were used for the MRI measurements. The percentage error and absolute percentage error were calculated for each method, and intraobserver and interobserver variability in 3D sonographic measurements was assessed with intraclass correlation coefficients (ICCs). Agreement between calculated and real volumes using the limits of agreement method was also evaluated.

RESULTS

The ICCs for the rotation angles indicated very good intraobserver and interobserver variability (6°, 0.995 and 0.996; 30°, 0.997 and 0.985). No systematic errors were observed in the mean percentage errors for 3D sonographic measurements or MRI volumetry. The lowest median absolute percentage error (1.76) was obtained with MRI volumetry, significantly lower than the values for sonography (6°, 5.00; P < .001; 30°, 5.49; P < .001). There were no significant differences in absolute percentage errors between the rotation angles (P = .82) and no significant differences in limits of agreement between 3D sonography and MRI (6°, P = .76; 30°, P = .39).

CONCLUSIONS

Three-dimensional sonographic volumetry was almost as accurate as MRI in this in vitro model and can be regarded as a good alternative method. Further research is needed to confirm these findings in vivo and to assess the prognostic value in fetuses with lung hypoplasia (eg, congenital diaphragmatic hernias).

Influence of different rotation angles in assessment of lung volumes by 3-dimensional sonography in comparison to magnetic resonance imaging in healthy fetuses

OBJECTIVES

Three-dimensional (3D) sonographic volumetry is established in gynecology and obstetrics. Assessment of the fetal lung volume by magnetic resonance imaging (MRI) in congenital diaphragmatic hernias has become a routine examination. In vitro studies have shown a good correlation between 3D sonographic measurements and MRI. The aim of this study was to compare the lung volumes of healthy fetuses assessed by 3D sonography to MRI measurements and to investigate the impact of different rotation angles.

METHODS

A total of 126 fetuses between 20 and 40 weeks' gestation were measured by 3D sonography, and 27 of them were also assessed by MRI. The sonographic volumes were calculated by the rotational technique (virtual organ computer-aided analysis) with rotation angles of 6° and 30°. To evaluate the accuracy of 3D sonographic volumetry, percentage error and absolute percentage error values were calculated using MRI volumes as reference points. Formulas to calculate total, right, and left fetal lung volumes according to gestational age and biometric parameters were derived by stepwise regression analysis.

RESULTS

Three-dimensional sonographic volumetry showed a high correlation compared to MRI (6° angle, R(2) = 0.971; 30° angle, R(2) = 0.917) with no systematic error for the 6° angle. Moreover, using the 6° rotation angle, the median absolute percentage error was significantly lower compared to the 30° angle (P < .001). The new formulas to calculate total lung volume in healthy fetuses only included gestational age and no biometric parameters (R(2) = 0.853).

CONCLUSIONS

Three-dimensional sonographic volumetry of lung volumes in healthy fetuses showed a good correlation with MRI. We recommend using an angle of 6° because it assessed the lung volume more accurately. The specifically designed equations help estimate lung volumes in healthy fetuses.

Comparison of inter- and intraobserver agreement and reliability between three different types of placental volume measurement technique (XI VOCAL, VOCAL and multiplanar) and validity in the in-vitro setting

OBJECTIVES

To compare XI VOCAL (eXtended Imaging Virtual Organ Computer-aided AnaLysis) for three-dimensional (3D) ultrasound volumetry of the placenta and of phantom objects with a rotational method using VOCAL and with the multiplanar method.

METHODS

We acquired 3D volume datasets from 32 fetuses at 11-14 weeks' gestation. Placental volume was calculated twice by each of two observers using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) methods. In addition, validity was assessed using the in-vitro setting with three phantom objects of known volume.

RESULTS

Both inter- and intraobserver reliabilities were very high for all three methods. There was no systematic bias between any two methods except between XI VOCAL (10 slices) and the multiplanar (1-mm interval) method, with a smaller volume using the former method. The limits of agreement were wide between any two of the three methods. In the in-vitro setting, there was a trend towards less valid measurements with the XI VOCAL technique and fewer slices. With the same number of steps, measurements made with VOCAL (12 degrees and 18 degrees) were more valid than were those made with XI VOCAL (15 and 10 slices, respectively).

CONCLUSION

XI VOCAL cannot be used interchangeably with VOCAL or multiplanar techniques in measuring placental volume at 11-14 weeks' gestation.

Fetal lung volume in fetuses with urinary tract malformations: comparison by 2D-, 3D-sonography and magnetic resonance imaging

OBJECTIVE

To evaluate the concordance between two-dimensional ultrasonography (2DUS), three-dimensional ultrasonography (3DUS) and magnetic resonance imaging (MRI) in the assessment of lung volume in fetuses with urinary tract malformations (UTM).

METHODS

This was a cross-sectional study involving 12 pregnancies between 19 and 34 weeks, with various fetal UTM. Pulmonary volume was obtained by 2DUS using the following equation: total lung volume = [right lung antero-posterior diameter (X) x transverse diameter (Y) x cranial-caudal diameter x 0.152 + left lung (X1) x (Y1) x (Z1) x 0.167]. Pulmonary volume by 3DUS was obtained using the virtual organ computer-aided analysis (VOCAL) method with a 30 degrees (VOL30), 18 degrees (VOL18) and 12 degrees (VOL12) rotation. A fast sequence of transverse lung section was also obtained by MRI. The intraclass correlation coefficient was used to evaluate the correlation between the three methods. The paired student t-test was used to compare the means.

RESULTS

There was a strong correlation between the three methods, and the highest correlations were between MRI and VOL18 for the right (ICC = 0.913) and left (ICC = 0.947) lungs. A strong correlation was also found between the lung volumes obtained through MRI and VOL12 as well as VOL18 (p = 0.544 and 0.286, respectively). However, for the left lung there was only a correlation between MRI and VOL12 (p = 0.49).

CONCLUSIONS

There is a good concordance between 3DUS (VOL12) and MRI in the evaluation of lung volume in fetuses with UTM.

Correlation of the fetal cerebellar volume with other fetal growth indices by three-dimensional ultrasound

OBJECTIVE

To verify the correlation of fetal cerebellar volume by three-dimensional ultrasound (3D US) with other indices of fetal growth in normal fetuses.

METHODS

This was a longitudinal prospective study involving 52 normal pregnant women between 20 and 32 weeks of gestation. The assessments of the fetal cerebellar volume were carried out at intervals of two weeks, and the method used was VOCAL (virtual organ computer-aided analysis) with a 30 degrees rotation angle. At each assessment, the following biometric indices were evaluated using the two-dimensional method: biparietal diameter, head circumference, transverse cerebellar diameter, femur length, and estimated fetal weight. We used Pearson's correlation coefficient to evaluate the correlation between fetal cerebellar volume and these indices; we also used polynomial regression analysis with fetal cerebellar volume as the dependent variable and the other indices as the independent variable.

RESULTS

The fetal cerebellar volume was highly correlated with gestational age (r = 0.94; p < 0.001) and with all other fetal growth indices (p < 0.001).

CONCLUSIONS

The assessment of the fetal cerebellar volume by 3D US is an important tool to evaluate fetal growth.

Three-dimensional ultrasonographic bladder volume measurement: reliability of the Virtual Organ Computer-Aided Analysis technique using different rotation steps

OBJECTIVE

The purpose of this study was to investigate the reliability of Virtual Organ Computer-Aided Analysis (VOCAL; GE Healthcare, Kretztechnik, Zipf, Austria) using the 4 standard rotation steps to measure the bladder volume with 3-dimensional (3D) ultrasonography.

METHODS

Using the 4 standard rotation steps of VOCAL, 2 independent observers made 3D volume measurement data sets from the urinary bladder (n = 180). Sets of 30, 20, 12, and 6 planes were obtained from the sequential rotations of 6 degrees, 9 degrees, 15 degrees, and 30 degrees, respectively. The internal contours of the bladders were determined manually. Reliability was evaluated with the intraclass correlation coefficient (ICC), and Bland-Altman plots were generated to examine bias and agreement. One-way analysis of variance was used to compare bladder volume measurements between the angles. P < .05 was considered statistically significant.

RESULTS

A high degree of reliability was observed between pairs of different rotation angles (ICC, 0.994-0.999). There was good agreement between all pairs of different rotation angles, with percentages of the mean difference ranging from -0.9% to 1.8%. No significant difference was found for bladder volume measurements by the VOCAL technique with varying rotation steps. Intraobserver and interobserver reliabilities were high (ICC, 0.994-0.998).

CONCLUSIONS

Urinary bladder volume measurement by the VOCAL technique using different rotation steps is highly reliable. A plane rotation of 30 degrees produces the fastest result.

Comparison of inter- and intraobserver agreement between three types of fetal volume measurement technique (XI VOCAL, VOCAL and multiplanar)

OBJECTIVES

To compare the new XI VOCAL (eXtended Imaging Virtual Organ Computer-aided Analysis) for three-dimensional (3D) ultrasound measurement of fetal volume with the conventional multiplanar technique and a rotational method using VOCAL.

METHODS

We acquired 3D volume datasets from 30 fetuses at 11-14 weeks of gestation using a commercially available ultrasound system. Fetal volume was calculated using XI VOCAL (with 5, 10, 15 and 20 slices), multiplanar (1-mm interval) and VOCAL (with 12 degrees, 18 degrees and 30 degrees rotation) techniques. The level of agreement for interobserver and intraobserver variability was determined and evaluated for all methods and reliability was assessed.

RESULTS

Fetal volume measurements obtained using XI VOCAL (10 slices) showed good correlation with those obtained using VOCAL (18 degrees) (r = 0.940, P = 0.076; intraclass correlation coefficient (ICC), 0.962 (95% CI, 0.920-0.982), P = 0.182), and XI VOCAL (15 slices) showed good correlation with VOCAL (12 degrees ) (r = 0.961, P = 0.092; ICC, 0.979 (95% CI, 0.957-0.990), P = 0.190). The mean difference between paired measurements by the XI VOCAL (10 slices) and VOCAL (18 degrees ) methods was 1.00 mL, while that by the XI VOCAL (15 slices) and VOCAL (12 degrees) methods was 0.90 mL. 95% limits of agreement were - 2.80 to 4.80 between XI VOCAL (10 slices) and VOCAL (18 degrees) and - 1.90 to 3.70 between XI VOCAL (15 slices) and VOCAL (12 degrees). There was a small difference in the time required to complete the fetal volume measurement between XI VOCAL and VOCAL when a similar number of slices or rotational steps was used (P < 0.05), XI VOCAL taking less time.

CONCLUSION

XI VOCAL (with 10, 15 and 20 slices) can be used interchangeably with the multiplanar technique (1-mm interval) for the measurement of fetal volume. XI VOCAL (10 slices) and VOCAL (18 degrees) can be used interchangeably, as can XI VOCAL (15 slices) and VOCAL (12 degrees), for the measurement of fetal volume.