Fetale Lungenentwicklung in der MRT

Foetal lung volumes in pregnant women who deliver very preterm: a pilot study

BACKGROUND

Infants born preterm are at increased risk of pulmonary morbidity. The contribution of antenatal factors to impairments in lung structure/function has not been fully elucidated. This study aimed to compare standardized lung volumes from foetuses that were delivered <32 weeks' gestation with foetuses that were delivered >37 weeks.

METHODS

Fourteen women who delivered <32 weeks gestation and 56 women who delivered >37 underwent a foetal MRI. Slice-volume reconstruction was then used and the foetal lungs were then segmented using multi-atlas approaches. Body volumes were calculated by manual segmentation and lung:body volume ratios generated.

RESULTS

Mean gestation at MRI of the preterm group was 27⁺² weeks (SD 2.9, range 20⁺⁶-31⁺³) and control group 25⁺³ weeks (SD 4.7 range 20⁺⁵-31⁺⁶). Mean gestation at delivery of the preterm group was 29⁺² weeks (SD 2.6, range 22⁺⁰-32⁺⁰). Lung:body volume ratios and foetal lung volumes were smaller in foetuses that were delivered preterm both with and without preterm premature rupture of membranes compared to those born at term (p < 0.001 in all cases).

CONCLUSIONS

Foetuses that were delivered very preterm had reduced lung volumes when standardized for foetal size, irrespective of ruptured membranes. These are novel findings and suggest an antenatal aetiology of insult and possible focus for future preventative therapies.

The Effects of Hemodynamic Alterations on Lung Volumes in Fetuses with Tetralogy of Fallot: An MRI Study

This study assessed whether the presence of tetralogy of Fallot (TOF) affects fetal lung development and whether these fetuses are at risk of pulmonary hypoplasia (PH). Furthermore, we investigated whether the degree of the concomitant pulmonary valve (PV) stenosis or a stenosis in the branch pulmonary arteries correlates with the fetal lung volume. Lung volumetry was performed in 16 fetuses with TOF who underwent MRI between gestational weeks 21 and 35 and in 22 controls. Fetal biometric data and the diameters of the PVs were evaluated by ultrasound. PV and branch pulmonary artery diameters were standardized (z-scores), and fetal lung volume/fetal body weight (FLV/FBW) ratios (ml/g) were calculated. The mean FLV/FBW ratio (0.031 ± 0.009 ml/g) in the TOF group was statistically significantly lower than in the control group (0.041 ± 0.009 ml/g; P = 0.003). None of the fetuses with TOF met the criterion for PH. FLV did not correlate with the degree of PV stenosis, but rather with the presence of a significant stenosis in at least one branch pulmonary artery. The presence of TOF moderately affects fetal lung growth, which is apparently not dependent on the degree of the PV stenosis. However, only an additional stenosis in at least one branch pulmonary artery was associated with a small FLV, but not with PH. Thus, reduced pulmonary blood flow may be offset by additional factors, such as the ability to establish a sufficient collateral system and to alter structural vascular size and, thus, pulmonary vascular resistance.

Pulmonary effects of prolonged oligohydramnios following mid-trimester rupture of the membranes--antenatal and postnatal management

Mid-trimester, preterm prelabour rupture of the membranes (PPROM) with prolonged oligohydramnios remains a challenge for both obstetricians and neonatologists. Although survival rates have improved, morbidity remains common particularly due to pulmonary insufficiency and pulmonary hypertension. The aetiology of abnormal lung development is unknown but may depend critically on pulmonary vascular development. Antenatal evaluation of at-risk foetuses by three-dimensional ultrasound and MRI is possible but the techniques need to be further assessed. Antenatal corticosteroids given in cases of PPROM reduce the incidence of neonatal death, respiratory distress syndrome, intraventricular haemorrhage and necrotising enterocolitis without increasing maternal or neonatal infection. The true risk-benefit ratio of antibiotics, tocolysis and strategies to normalise amniotic fluid volume remains less clear. There is no consensus regarding the optimal ventilation strategy to support infants with pulmonary insufficiency following PPROM, and further work is required to determine whether and which pulmonary vasodilators improve long-term outcome in these infants.