Fetal magnetic resonance imaging in the evaluation of congenital diaphragmatic anomalies

Background: Congenital abnormalities of the diaphragm cause impairment of lung development and are an important cause of post-natal morbidity and mortality. Congenital diaphragmatic eventration (CDE), a less sinister diaphragmatic anomaly compared to the more common congenital diaphragmatic hernia (CDH), often tends to mimic CDH on prenatal imaging. This study evaluates the role of fetal magnetic resonance imaging (MRI) in differentiating these two entities. Results: This was a retrospective study which included fetal MRI studies done in patients with ultrasound diagnosis of fetal diaphragmatic anomaly. MRI exam was performed with a 1.5 T superconducting system with eight-element torso array coil. The images were studied by two radiologists experienced in fetal imaging in consensus. Diagnosis of CDE was made if the dome of the diaphragm was visualized as a thin hypointense line separating the lung from abdominal structures on coronal and sagittal MRI sequences. If this thin hypointense line was not visualized, a diagnosis of CDH was made. The findings were then correlated with autopsy/intra-operative findings/post-natal imaging follow-up. A total of 12 patients were included in the study. In these 12 patients, 13 diaphragmatic abnormalities were diagnosed on MRI (1 fetus had bilateral diaphragmatic anomaly). Of the 13 diaphragmatic anomalies detected, 7 (54%) were CDH and 6 (46%) were CDE. The type of diaphragmatic anomaly was correctly identified on MRI in all except one fetus in which CDE was misdiagnosed as CDH. The Fisher exact test statistic value was 0.0047. The result was significant at p < 0.01. Conclusion: Fetal MRI is a useful tool for assessing congenital diaphragmatic anomalies. Visualization of the diaphragm on coronal and sagittal images helps in diagnosis of complete CDE and differentiating it from the more sinister CDH.