Low-intensity fetal lungs on MRI may suggest the diagnosis of pulmonary hypoplasia.

Background: Pulmonary hypoplasia is a common cause of neonatal death. Despite the recent advances in prenatal diagnosis with US, the diagnosis of pulmonary hypoplasia is difficult. The recent application of fast MR imaging may provide additional valuable information.
Objective: To evaluate pulmonary hypoplasia in the fetus with MRI.
Materials and Methods: The subjects comprised 23 fetuses (18-40 weeks' gestation), including major anomalies diagnosed on fetal ultrasonography (n = 20), maternal abnormality (n = 2) and one normal twin. MRI was performed with a 1.5-T magnet and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. MR images were interpreted by three radiologists with special attention to the intensity of the lungs. The lung-to-liver intensity ratio was calculated by means of region-of-interest (ROI) analysis. The diagnosis of pulmonary hypoplasia depended on clinical, surgical and autopsy findings.
Results: All fetuses with normal pulmonary development showed high intensity in the lung except for one fetus at 24 weeks' gestational age. All fetuses with pulmonary hypoplasia showed lung of low intensity.
Conclusions: Low-intensity fetal lung on MRI imaging indicates pulmonary hypoplasia after 26 weeks' gestation.