Functional Evaluation of the Fetal Lung by Functional Magnetic Resonance Imaging - Blood Oxygenation Level Dependent (MRI-BOLD), in Congenital Diaphragmatic and Parietal Malformations

During the fetal period, there is in the lungs a permanent flow and pressure variations between the "inhaled" amniotic fluid and alveolar secretions, which are essential for pulmonary development. A disruption of this physiological mechanism can induce disorders of the respiratory function, which go from simple delay of maturation to hypoplasia. Respiratory function involves the thoracic muscles (diaphragmatic and intercostal) but also the abdominal muscles, that explains why breathing difficulties are found at birth in neonates with diaphragmatic hernia but also abdominal wall malformations. This pulmonary involvement highly contributes to the morbidity observed at birth, for which strong prenatal predictive criteria are lacking. Pulmonary volume measurement by the lung-to-head-ratio is widely used for diaphragmatic hernia has been extended to other congenital malformations, because no other available criteria. The lung-to-head-ratio is a parameter well correlated with survival but insufficiently with morbidity and sequelae. New functional imaging techniques are in development. Among them, the Blood Oxygen Level Dependent uses hemoglobin as an endogenous contrast agent. It is based on the comparison of a basic status in ambient air with status after oxygenation. It gives a functional evaluation of the organs. But this technique has never been evaluated in the fetal lung yet. The objective of the study is to evaluate the quality of the response to the Blood Oxygen Level Dependent effect in fetuses with diaphragmatic hernias and abdominal wall malformations and to correlate with postnatal respiratory outcome. It is an original exploratory study and no preliminary data are thus available. If a correlation is found, the Blood Oxygen Level Dependent effect of the fetal lung may be considered as an early functional marker of postnatal lung function. It could then be used in addition to lung-to-head-ratio during prenatal counseling. The final goal is to be able to detect early in the fetus pulmonary insufficiency to help prenatal counseling and perinatal care.