Factors affecting length of stay according to bronchopulmonary dysplasia severity: a nationwide cohort study in Korea

BACKGROUND

Longer hospitalizations for preterm infants with bronchopulmonary dysplasia (BPD) delay developmental outcomes, increase the risk for hospital-acquired complications, and exert a substantial socioeconomic burden. This study aimed to identify factors associated with an extended length of stay (LOS) at different levels of severity of BPD.

METHODS

A cohort study was conducted using the Korean Neonatal Network registry of very low birth weight infants with BPD between 2013 and 2017 through retrospective analysis.

RESULTS

A total of 4263 infants were diagnosed with BPD. For mild BPD, infants requiring surgical treatment for patent ductus arteriosus needed a longer LOS [eadjusted β coefficients (adj β) 1.041; 95% confidence interval (CI): 0.01-0.08] and hydrocephalus (eadj β 1.094; 95% CI 0.01-0.17). In moderate BPD, infants administered steroids or with intraventricular hemorrhage required a longer LOS (eadj β 1.041; 95% CI 0.00-0.07 and eadj β 1.271; 95% CI 0.11-0.38, respectively). In severe BPD, infants with comorbidities required a longer LOS: pulmonary hypertension (eadj β 1.174; 95% CI 0.09-0.23), administrated steroid for BPD (eadj β 1.116; 95% CI 0.07-0.14), sepsis (eadj β 1.062; 95% CI 0.01-0.11), patent ductus arteriosus requiring surgical ligation (eadj β 1.041; 95% CI 0.00-0.08), and intraventricular hemorrhage (eadj β 1.016; 95% CI 0.05-0.26). Additionally, the higher the clinical risk index score, the longer the LOS needed for infants in all groups.

CONCLUSIONS

The factors affecting LOS differed according to the severity of BPD. Individualized approaches to reducing LOS may be devised using knowledge of the various risk factors affecting LOS by BPD severity.

Fetal lung MRI and features predicting post-natal outcome: a scoping review of the current literature

The outcome for infants with fetal lung pathologies not only depends on the nature of the pathology, but the impact it has on the developing lungs. The main prognostic factor is the degree of pulmonary hypoplasia, but this is not detectable pre-natally. Imaging techniques aim to simulate these features with a variety of surrogate measurements, including lung volume and MRI signal intensity. Despite the complexity of the various research studies and lack of consistent methodology, this scoping review aims to summarise current applications, and promising techniques requiring further investigation.

Fetal MRI radiomics: non-invasive and reproducible quantification of human lung maturity

OBJECTIVES

To assess the reproducibility of radiomics features extracted from the developing lung in repeated in-vivo fetal MRI acquisitions.

METHODS

In-vivo MRI (1.5 Tesla) scans of 30 fetuses, each including two axial and one coronal T2-weighted sequences of the whole lung with all other acquisition parameters kept constant, were retrospectively identified. Manual segmentation of the lungs was performed using ITK-Snap. One hundred radiomics features were extracted from fetal lung MRI data using Pyradiomics, resulting in 90 datasets. Intra-class correlation coefficients (ICC) of radiomics features were calculated between baseline and repeat axial acquisitions and between baseline axial and coronal acquisitions.

RESULTS

MRI data of 30 fetuses (12 [40%] females, 18 [60%] males) at a median gestational age of 24 + 5 gestational weeks plus days (GW) (interquartile range [IQR] 3 + 3 GW, range 21 + 1 to 32 + 6 GW) were included. Median ICC of radiomics features between baseline and repeat axial MR acquisitions was 0.92 (IQR 0.13, range 0.33 to 1), with 60 features exhibiting excellent (ICC > 0.9), 27 good (> 0.75-0.9), twelve moderate (0.5-0.75), and one poor (ICC < 0.5) reproducibility. Median ICC of radiomics features between baseline axial and coronal MR acquisitions was 0.79 (IQR 0.15, range 0.2 to 1), with 20 features exhibiting excellent, 47 good, 29 moderate, and four poor reproducibility.

CONCLUSION

Standardized in-vivo fetal MRI allows reproducible extraction of lung radiomics features. In the future, radiomics analysis may improve diagnostic and prognostic yield of fetal MRI in normal and pathologic lung development.

KEY POINTS

• Non-invasive fetal MRI acquired using a standardized protocol allows reproducible extraction of radiomics features from the developing lung for objective tissue characterization. • Alteration of imaging plane between fetal MRI acquisitions has a negative impact on lung radiomics feature reproducibility. • Fetal MRI radiomics features reflecting the microstructure and shape of the fetal lung could complement observed-to-expected lung volume in the prediction of postnatal outcome and optimal treatment of fetuses with abnormal lung development in the future.

Prenatal quantification of human foetal lung and liver elasticities between 24 and 39 weeks of gestation using 2D shear wave elastography

Objectives

To quantify and model normal foetal lung and liver elasticities between 24 and 39 weeks of gestation (WG) using two-dimensional shear wave elastography (2D-SWE). To assess the impact of the distance between the probe and the target organ on the estimation of elasticity values.

Methods

Measurements of normal foetal lungs and liver elasticity were prospectively repeated monthly between 24 and 39 WG in 72 foetuses using 2D-SWE. Elasticity was quantified in the proximal lung and in the region inside the hepatic portal sinus. The distance between the probe and the target organ was recorded. Trajectories representing foetal lung and liver maturation from at least 3 measurements over time were modelled.

Results

The average elasticity for the lung and liver was significantly different from 24 WG to 36 WG (p < 0.01). Liver elasticity increased during gestation (3.86 kPa at 24 WG versus 4.45 kPa at 39 WG). From 24 WG to 32 WG, lung elasticity gradually increased (4.12kPa at 24 WG, 4.91kPa at 28 WG, 5.03kPa at 32 WG, p < 0.002). After 32 WG, lung elasticity decreased to 4.54kPa at 36 WG and 3.94kPa at 39 WG. The dispersion of the average elasticity values was greater for the lung than for the liver (p < 0.0001). Variation in the elasticity values was less important for the liver than for the lung. The values were considered valid and repeatable except for a probe-lung distance above 8cm.

Conclusion

Foetal lung and liver elasticities evolve differently through gestation. This could reflect the tissue maturation of both organs during gestation.

Trial registration

clinicaltrials.gov identifier: NCT03834805

Key Points

• Prenatal quantification of foetal lung elasticity using 2D shear wave elastography could be a new prenatal parameter for exploring foetal lung maturity.

• Liver elasticity increased progressively from 24 weeks of gestation (WG) to 39 WG, while lung elasticity increased first between 24 and 32 WG and then decreased after 32 WG.

• The values of elasticity are considered valid and repeatable except for a probe-lung distance above 8cm.

Imaging Review of Obstetric Sequelae of Maternal Diabetes Mellitus

Diabetes mellitus, whether preexisting or gestational, poses significant risk to both the mother and the developing fetus. A myriad of potential fetal complications in the setting of diabetic pregnancies include, among others, congenital anomalies, delayed fetal lung maturity, macrosomia, and increased perinatal morbidity and mortality. Congenital anomalies most commonly involve the nervous, cardiovascular, genitourinary, and musculoskeletal systems. Delayed fetal lung maturity, probably secondary to hyperglycemia suppressing surfactant secretion, is a major determinant of perinatal morbidity and mortality. Besides the potential complications encountered during cesarean delivery in macrosomic fetuses, vaginal delivery is also associated with increased risks of shoulder dystocia, clavicular and humeral fractures, and brachial plexus palsy. Maternal complications are related to the increased risk of hypertensive diseases of pregnancy and associated preeclampsia and hemolysis, elevated liver function, and low platelets (HELLP) syndrome, as well as complications encountered at the time of delivery secondary to fetal macrosomia and cesarean delivery. Additional conditions encountered in the setting of maternal diabetes include polyhydramnios, placental thickening, and two-vessel umbilical cord, each of which is associated with adverse fetal and maternal outcomes including fetal growth restriction, preterm labor, placental abruption, and premature rupture of membranes. Imaging plays a vital role in the evaluation of the mother and the fetus and can provide invaluable information that can be used by maternal fetal medicine to manage this patient population effectively. The authors review the pathophysiologic alterations induced by diabetes in pregnancy, discuss the imaging spectrum of diabetic embryopathy, and provide a detailed review of potential associated maternal complications. Online supplemental material is available for this article. ^©RSNA, 2021.

Comparison of fetal lung maturation in fetuses with intrauterine growth restriction with control group, using lung volume, lung/liver and lung/muscle signal intensity and apparent diffusion coefficient ratios on different magnetic resonance imaging sequences

PURPOSE

To compare lung volume, lung apparent diffusion coefficient (ADC) and signal intensity ratio (SIR) on different magnetic resonance imaging (MRI) sequences between intrauterine growth restriction (IUGR) fetuses and the control group.

MATERIALS AND METHODS

49 IUGR and 58 non-IUGR fetuses were imaged using 3 Tesla MRI units. Total lung volume (TLV), lung/liver SIR (LLSIR) and lung/muscle SIR (LMSIR) in T1 and T2-weighted sequences and lung/liver ADC ratio (LLADCR) and lung/muscle ADC ratio (LMADCR) were assessed.

RESULTS

LLSIR and LMSIR were significantly higher in the T1-weighted sequence (p-value: .03) and LLADCR and LMADCR were significantly lower on diffusion-weighted imaging (DWI) in IUGR fetuses compared to the control group (p-value: .01). There was no significant difference in SIRs in the T2-weighted sequence between the two groups. Although TLV was increased with gestational age in both groups, it was significantly lower in the IUGR group (mean: 82 ± 22.7 ml vs. 110.8 ± 18 ml, p-value: <.001).

CONCLUSION

The T1-weighted sequence and DWI seem to be better than the T2-weighted sequence for assessing the faint difference of lung maturity between groups. However, SIR differences were not as meaningful as TLV differences and this could be related to the complex maturation process in IUGR fetuses as the effect of higher endogenous corticosteroids.

Magnetic Resonance Prediction of Lung Maturity in Fetuses With Congenital Diaphragmatic Hernia

ABSTRACT

To determine if lung to liver MR T2 signal ratio is predictive of neonatal outcome in fetuses with congenital diaphragmatic hernia (CDH).After Interal Review Board approval, the PACS systems at the University of Washington and University of Utah were searched for cases having an in utero fetal MR examination diagnostic of CDH. Inclusion criteria were at least 1 prior ultrasound demonstrating a CDH and an MR obtained within 1 week of that prior ultrasound.A total of 69 patients from the University of Utah and 13 from the University of Washington satisfied the inclusion criteria for a total of 82. After adjusting for gestational age and contralateral lung volume, there was little apparent association between contralateral lung to liver MR T2 signal and 5-minute Apgar score and neonatal mortality When considering neonatal Apgar and mortality, increasing contralateral lung volume was significantly associated with lower risk (hazard ratio, 0.40 per doubling; 95% confidence interval, 0.24-0.69; P = 0.001) as expected.Our data demonstrate that the lung to liver MR signal ratio was not predictive of outcome. The measurement of contralateral lung area, and gestational age at the time of the examination (time of diagnosis) are still the best predictors of poor neonatal outcome.

Prenatal evaluation of functional pulmonary hypoplasia via fetal magnetic resonance imaging

OBJECTIVE

The purpose of this study was to retrospectively examine the use of lung-to-liver signal intensity ratio (LLSIR) on T2-weighted images to predict functional pulmonary hypoplasia.

METHODS

The subjects of this study were pregnant women who underwent magnetic resonance imaging (MRI). Patients who required nitric oxide inhalation and those who died from respiratory disorders were classified as having functional pulmonary hypoplasia (FPH). All other cases were presented as the control group. We retrospectively analyzed MRI and perinatal data. LLSIR was defined as the ratio of lung signal intensity to liver signal intensity. We examined the relationship between LLSIR and gestational age, compared the LLSIRs in the two groups, and calculated the best cut-off value of the LLSIR to predict FPH.

RESULTS

One hundred and ninety-one patients were eligible for this study, and 12 cases were classified as having FPH. In the control group, LLSIR increased with age (r = 0.383, p < 0.001). We used the observed/expected LLSIR (o/e LLSIR), which was the ratio of obtained LLSIR to expected LLSIR calculated by the regression line to correct the effect of gestational age. In the FHP group, o/e LLSIR was significantly lower than in the control group (p < 0.001). A receiver operating characteristic curve analysis showed that cases with o/e LLSIR above 0.85 were less likely to cause FPH.

CONCLUSIONS

Low o/e LLSIR might reflect the histological characteristics of hypoplastic lung structures. O/e LLSIR seems to be a useful MRI parameter for screening FPH.

Assessment of BOLD response in the fetal lung

OBJECTIVE

Assessment of lung development and maturity is of utmost importance in prenatal counseling. Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs. To date, no data are available in fetal lungs and nothing is known about the existence of a BOLD effect in the lungs. The aim of our study was to evaluate if a BOLD response could be detected in fetal lungs.

MATERIALS AND METHODS

From January 2014 to December 2016, 38 healthy pregnant women were prospectively enrolled. After a routine scan on a 1.5-T MRI device (normoxic period), maternal hyperoxia was induced for 5 min before the BOLD sequence (hyperoxic period). R2* was evaluated by fitting average intensity of the signal, both for normoxic (norm) and hyperoxic (hyper) periods.

RESULTS

A significant BOLD response was observed after maternal hyperoxia in the lungs with a mean R2* decrease of 12.1 ± 2.5% (p < 0.001), in line with the placenta response with a mean R2* decrease of 19.2 ± 5.9% (p < 0.0001), confirming appropriate oxygen uptake. Conversely, no significant BOLD effect was observed for the brain nor the liver with a mean ∆R2* of 3.6 ± 3.1% (p = 0.64) and 2.8 ± 3.7% (p = 0.23).

CONCLUSION

This study shows for the first time in human that a BOLD response can be observed in the normal fetal lung despite its prenatal "non-functional status." If confirmed in congenital lung and chest malformations, this property could be used in addition to the lung volume for a better prediction of postnatal respiratory status.

KEY POINTS

• Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs and could have interesting implications for the fetal organs. • Assessment of lung development is of utmost importance in prenatal counseling, but to date no data are available in fetal lungs. • BOLD response can be observed in the normal fetal lung opening the way to studies on fetus with pathological lungs.

Magnetic Resonance Imaging in Pregnancy with Intrauterine Growth Restriction: A Pilot Study

Objective

Intrauterine growth restriction (IUGR) is a major cause of late stillbirth, though not all compromised babies remain small or are considered growth restricted as pregnancy progresses. Fetal Magnetic Resonance Imaging (f-MRI) represents a second-line tool to study pregnancies with IUGR fetuses. The aim of our study was to evaluate the usefulness of f-MRI on predicting fetal growth and the offspring's perinatal respiratory outcome.

Design

All f-MRI performed between 2014 and 2016 in Siena were analysed. Pregnancies with IUGR (Study group (SG)) were recruited together with a control population (Control group (CG)), coupled for gestational age (GA) at the time of f-MRI (mean GA 31 wks). Neonatal information was collected. The f-MRI protocol consisted of T2w images. Six regions of interest (ROI) were placed as follows: 2 on the lung, 2 on the liver, and 2 on the amniotic fluid. The signal intensities (SI) of each ROI were measured. The SI lung to liver ratio (SI lung/liver) and SI lung to amniotic fluid ratio (SI lung/amniotic fluid) were obtained for each fetus. Each ratio was compared between SG and CG. Therefore, SG was divided into two subgroups: adequate and small for gestational age (AGA and SGA) newborns. All measurements were related to offspring's perinatal respiratory outcome.

Results

SI lung/liver was linearly related with GA at the time of f-MRI and with EFW. SI lung/amniotic fluid was significantly higher in SG than in CG (p = 0,014). In contrast, among SG, lower values of SI lung/amniotic fluid were found in the SGA compared to AGA (p = 0,036). The days of oxygen supply were higher in the SGA subgroup than in the AGA subgroup (p = 0,028).

Conclusions

SI lung/liver increases with fetal lung maturation and appears to be useful to estimate intrauterine fetal growth. SI lung/amniotic fluid seems to be a reliable predictive index to distinguish the IUGR fetuses that can recover their growth from those that were born SGA. f-MRI represents a promising frontier to predict IUGR fetus outcome, thus contributing to ameliorate the perinatal management.

Feasibility of two-dimensional ultrasound shear wave elastography of human fetal lungs and liver: A pilot study

PURPOSE

The first aim was to evaluate feasibility and reproducibility of 2-dimensional ultrasound (2D) shear wave elastography (SWE) of human fetal lungs and liver between 24 and 34weeks of gestation. The second aim was to model fetal lung-to-liver elastography ratio (LLE ratio) and to assess its variations according to gestational age and maternal administration of corticosteroids.

MATERIAL AND METHODS

2D-SWE examinations were prospectively performed in fetuses of women with an uncomplicated pregnancy (group 1) and fetuses of women with a threatened preterm labor requiring administration of corticosteroids (group 2). Two 2D-SWE examinations were performed at "day 0" and "day 2" in group 1; before and 24hours after a course of corticosteroid in group 2. Three operators performed 2 cycles of 3 measurements on the lung (regions A1, A2, A3) and the liver (regions IV, V, VI). Repeatability and reproducibility of measurements were calculated. The fetal LLE ratio was modeled from the most reproducible regions.

RESULTS

Fifty-five women were enrolled in group 1 and 48 in group 2. For the lung, 8.6% of measurements were considered invalid and 6.9% for the liver. The most reproducible region for the lung was A3 [ICC between 0.70 (95% CI: 0.42-0.85) and 0.78 (95% CI: 0.48-0.90)] and region VI for the liver [ICC between 0.70 (95% CI: 0.40-0.85) and 0.84 (95% CI: 0.60-0.94)]. According to gestational age, a moderate positive linear correlation was found for stiffness values of A3 (R=0.56), V (R=0.46) and VI (R=0.44). LLE ratio values at "day 0" were not different between the two groups but decreased at "day 2" in group 2 (0.2; 95% CI: 0.07-0.34; P<0.001).

CONCLUSION

Quantitative fetal lung and liver stiffness measurements are possible with 2D-SWE with acceptable reproducibility.

A new approach to risk stratification using fetal MRI to predict outcomes in congenital diaphragmatic hernia: the preliminary retrospective single institutional study

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a condition with a wide range of severity. Prenatal diagnosis is essential to optimize postnatal management, especially for severe cases. The lung to head ratio (LHR) and liver herniation estimated by prenatal ultrasound has been used as prenatal predictors in CDH. However, reliability of these factors remains to be proven and prediction of outcome from prenatal imaging is still challenging. We propose our new stratification system using lung to liver signal intensity ratio (LLSIR) in fetal MRI, which has been shown to be related to pulmonary maturation.

METHODS

Retrospective chart review was conducted on 25 infants with CDH treated from 2009 through 2016 in our hospital. We stratified patients according to fetal T2-weighted MRI as Grade I, detectable ipsilateral lung at the apex; Grade II, undetectable ipsilateral lung at the apex and contralateral LLSR ≥2.0; Grade III, undetectable ipsilateral lung at the apex and contralateral LLSR <2.0. To evaluate this stratification system, we analyzed survival, severity [inhaled nitric oxide (iNO) usage with or without extracorporeal membrane oxygenation (ECMO)], and requirement of patch closure.

RESULTS

All 15 patients survived in Grade I, while 2 out of 6 died in Grade II, and 3 out of 4 died in Grade III (P=0.003). Four were severe in Grade I, and all in Grade II and III who survived (P=0.007). One needed patch in Grade I, and all in Grade II and III (OR: 414,238,332; 95% CI, 0-∞). Liver herniation was noted in five patients, and significantly associated with survival (P=0.04), however, neither with severity (P=1.00) nor with the requirement of patch closure (P=0.52).

CONCLUSIONS

The risk stratification algorithm using contralateral LLSIR in fetal MRI could be useful and more reliable than liver herniation to predict survival, severity, and need of patch closure. Further investigation is warranted.

Magnetic Resonance Imaging for Quantitative Assessment of Lung Aeration: A Pilot Translational Study

Background: Computed tomography is the gold standard for lung aeration assessment, but exposure to ionizing radiation limits its application. We assessed the ability of magnetic resonance imaging (MRI) to detect changes in lung aeration in ex vivo isolated swine lung and the potential of translation of the findings to human MRI scans.

Methods: We performed MRI scans in 11 isolated non-injured and injured swine lungs, as well as 6 patients both pre- and post-operatively. Images were obtained using a 1.5 T MRI scanner, with T₁ – weighted volumetric interpolated breath-hold examination (VIBE) and T₂ – weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. We scanned swine lungs, with reference samples of water and muscle, at different airway pressure levels: 0, 40, 10, 2 cmH₂O. We investigated the relations between MRI signal intensity and both lung density and gas content fraction. We analyzed patients’ images according to the findings of the ex vivo model.

Results: In the ex vivo samples, the lung T₁ – VIBE signal intensity normalized to water or muscle reference signal correlated with lung density (r² = 0.98). Thresholds for poorly and non-aerated lung tissue, expressed as MRI intensity attenuation factor compared to the deflated lung, were estimated as 0.70 [95% CI: 0.65–0.74] and 0.28 [95% CI: 0.27–0.30], respectively. In patients, dorsal versus ventral regions had a higher MRI signal intensity both pre- and post-operatively (p = 0.031). Comparing post- versus pre-operative scans, lung volume decreased (p = 0.028), while the following increased: MRI signal intensity in ventral (p = 0.043) and dorsal (p < 0.0001) regions, and percentages of non-aerated (p = 0.028) and poorly aerated tissue volumes (p = 0.028).

Conclusion: Magnetic resonance imaging signal intensity is a function of lung density, decreasing linearly with increasing gas content. Lung MRI might be useful for estimating lung aeration. Compared to CT, this technique is radiation-free but requires a longer acquisition time and has a lower spatial resolution.

Magnetic resonance assessment of fetal lung maturity: comparison between signal intensity and volume measurement

PURPOSE

We evaluated the associations between gestational age (GA) and lung-to-liver signal intensity ratio (LLSIR) and fetal lung volume (FLV) using magnetic resonance imaging (MRI). Moreover, we evaluated the reproducibility of these measurements.

MATERIALS AND METHODS

LLSIR and FLV were measured using single-shot fast spin-echo MRI in 88 consecutive fetuses. The Spearman test was used to assess the relationships between (1) LLSIR and GA, and (2) FLV and GA in 81 fetuses without lung abnormalities. Intra- and inter-observer reliabilities were assessed using intra-class correlation coefficients (ICCs).

RESULTS

Overall, GA and LLSIR were significantly correlated (r = 0.62, p < 0.001). However, GA and LLSIR were only significantly correlated during the third trimester (before third trimester: r = 0.39, p = 0.08; during third trimester: r = 0.46, p < 0.001). Overall, GA and FLV were significantly correlated (r = 0.72, p < 0.001). FLV was significantly correlated with GA before (r = 0.86, p < 0.001) and during the third trimester (r = 0.47, p < 0.001). All ICCs were above 0.90.

CONCLUSIONS

LLSIR and FLV are useful for the assessment of fetal lung maturity and are highly reproducible. Before the third trimester, FLV is more suitable than LLSIR for the evaluation of fetal lung maturity.

The fetal lung-to-liver signal intensity ratio on magnetic resonance imaging as a predictor of outcomes from isolated congenital diaphragmatic hernia

PURPOSE

We investigated the developmental changes in the unaffected contralateral lungs of patients with isolated left-sided congenital diaphragmatic hernia (CDH) using signal intensity ratios on prenatal magnetic resonance imaging (MRI) and determined whether these changes correlated with clinical outcomes.

METHODS

We performed 47 fetal MRI screens on 30 patients with isolated left-sided CDH. A cohort of 88 fetuses was selected as the control. We calculated the lung-to-liver signal intensity ratio (LLSIR) using region of interest analysis and compared LLSIR between the groups and between those in the CDH group with good and poor prognoses.

RESULTS

In the control group, LLSIR increased as pregnancy progressed [regression line = 2.232 + 0.135 × (GW-23), r = 0.669]. In the CDH group, especially in the poor prognosis group, LLSIR did not significantly increase as pregnancy progressed [regression line for good prognosis = 1.827 + 0.092 × (gestational week-23), r = 0.733; regression line for poor prognosis = 1.731 + 0.025 × (gestational week-23), r = 0.634].

CONCLUSION

Fetal LLSIR on T2-weighted MRI is an accurate marker of fetal lung maturity that correlates with postnatal survival and can potentially be used as a prognostic parameter in CDH management.

Feasibility of 2-D ultrasound shear wave elastography of fetal lungs in case of threatened preterm labour: a study protocol

INTRODUCTION

2-D ultrasound shear wave elastography (SWE) could be considered as a new noninvasive tool for monitoring fetal lung development based on evaluation of mechanical properties during pregnancy. Interesting results are available concerning the use of SWE on developing organs, especially on premature infants and animal models. The main objective in this study is to evaluate the feasibility of 2-D SWE in human fetal lungs between 24 and 34 weeks of gestation (WG). The secondary objective is to modellise fetal lung-to-liver elastography ratio (LLE ratio) and to assess variations between normal lung and lung surfactant-enriched after a corticosteroids course indicated for a threatened preterm labour (TPL).

METHODS/DESIGN

A prospective case-control study will be performed between 24 and 34 WG. Fetal lungs and liver will be explored by SWE into two groups: fetuses of women with an uncomplicated pregnancy (control group) and fetuses of women with a TPL requiring administration of corticosteroids (cases group). LLE ratio will be defined as the value of the lung elasticity divided by the value of the liver elasticity.Primary judgement criterion is the value of elasticity modulus expressed in kilopascal. Lungs and liver will be explored through three measurements to define the most reproducible regions with the lowest intra- and inter-observer variability. Feasibility will be evaluated by assessing the number of examinations performed and the number of examinations with interpretable results. Intra- and inter-observer reproducibility will be evaluated by means of the intra-class correlation coefficient.

ETHICS AND DISSEMINATION

Approval of the study protocol was obtained from the human ethical research committee (Comité de Protection des Personnes EST II, process number 15/494) and the French National Agency for Medicines and Health Products Safety (process number 2015-A01575-44). All participants will sign a statement of informed consent.

TRIAL REGISTRATION NUMBER

NCT02870608; Recruiting.

Combined measurement of fetal lung volume and pulmonary artery resistance index is more accurate for prediction of neonatal respiratory distress syndrome in preterm fetuses: a pilot study

OBJECTIVE

The objective of this study is to estimate optimal cut-off values for mean fetal lung volume (FLV) and pulmonary artery resistance index (PA-RI) as non-invasive measures to predict neonatal respiratory distress syndrome (RDS) in preterm fetuses.

METHODS

A prospective study conducted at Ain Shams University Maternity Hospital, Egypt from May 2015 to July 2017: 80 eligible women diagnosed with preterm labor were recruited at 32-36 weeks' gestation. Before delivery, three-dimensional ultrasound was used to estimate FLV using virtual organ computer-aided analysis (VOCAL), while PA-RI was measured by Doppler ultrasonography.

RESULTS

A total of 80 women were examined. Thirty-seven (46%) of the newborns developed neonatal RDS. FLV was significantly lower in neonates who developed RDS (p = .04), whereas PARI was significantly higher in those who did not (p = .02). Cut-off values of FLV ≤27.2 cm³ and PARI ≥0.77 predicted the subsequent development of RDS. Combining both cut-offs generated a more sensitive and specific methodical approach for the prediction of RDS (sensitivity 100%, specificity 88.5%).

CONCLUSION

Measurement of FLV or PA-RI can predict RDS in preterm fetuses. Combined use of both measures bolstered their predictive significance.

Increased fetal lung T2 signal is not due to increasing surfactant concentration: an in vitro T2 mapping analysis

OBJECT

The aim of this study was to perform in vitro T2 mapping of serial dilutions of pharmaceutical surfactant.

MATERIALS AND METHODS

Magnetic resonance imaging. Magnetic resonance scanning was performed on serial dilutions of surfactant on large bore clinical magnets at a field strength of 1.5 T Philips and 3.0 T (Achieva TX, Philips Healthcare, the Netherlands).

RESULTS

The curves demonstrate a small increasing trend between surfactant concentration and R2 (shortened T2's), with a 7.3% increase in R2 for each doubling of surfactant concentration (95% confidence interval: 6.1-8.6%, p < 0.001).

CONCLUSIONS

The increasing lung/liver T2 signal ratio seen in fetal lungs with increasing gestational age is not due to increasing surfactant concentration. © 2016 John Wiley & Sons, Ltd.

Prenatal diagnosis of fetal respiratory function: evaluation of fetal lung maturity using lung-to-liver signal intensity ratio at magnetic resonance imaging

Objective

The purpose of this retrospective study is to determine the fetal lung-to-liver signal intensity ratio (LLSIR) on T2-weighted images for the prediction of neonatal respiratory outcome.

Methods

One hundred ten fetuses who underwent magnetic resonance imaging (MRI) examination for various indications after 22 weeks of gestation participated in this study. LLSIR was measured as the ratio of signal intensities of the fetal lung and liver on T2-weighted images at MRI. We examined the changes of the ratio with advancing gestation and the relations between LLSIR and the presence of the severe respiratory disorder (SRD) after birth. The best cut-off value of the LLSIR to predict respiratory outcome after birth was calculated using receiver operating characteristic (ROC) curve analysis.

Results

Lung-to-liver signal intensity ratio correlated significantly with advancing gestational age (R = 0.35, p < 0.001). The non-SRD group had higher LLSIR compared with the SRD group (2.15 ± 0.30 vs. 1.53 ± 0.40, p < 0.001). ROC curve analysis showed that fetuses with an LLSIR < 2.00 were more likely to develop SRD [sensitivity: 100%, 95% confidence interval (CI): 52–100%; specificity: 73%, 95% CI 54–88%].

Conclusion

The fetal LLSIR on T2-weighted images is an accurate marker to diagnose the fetal lung maturity. © 2014 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd.