Purpose: To demonstrate the feasibility of lung signal measurements on fetal MRI, present normal signal intensity curves, and assess its value to predict pulmonary hypoplasia.
Patients and methods: Prospective multicentric study of 115 fetuses without lung disease and 33 fetuses with left diaphragmatic hernia and high risk of pulmonary hypoplasia. Signal measurements were obtained of the lungs, liver and psoas from fast heavily T2W sequences (HASTE, 2 measurements and 2 orthogonal planes for each organ, oval-shaped ROI of 1 cm2 for lungs and liver, and 0.5 cm2 for the psoas).
Results: No direct linear relationship existed between lung signal intensity and gestational age. A direct linear relationship existed between liver signal and gestational age, and between psoas signal and gestational age. An exponential relationship existed for the ratios left lung/liver, right lung/liver, left lung/psoas and right lung/psoas. The inter-observer agreement was excellent, ranging between 0.888 and 0.926. Significant differences were observed between normal fetuses and fetuses with diaphragmatic hernia for the right lung/liver and left lung/psoas ratios.
Conclusion: Normal fetal lung signal intensity curves can be obtained. Lungs at risk of hypoplasia presented significant alterations of signal ratios. The prognostic value of such results requires additional postnatal clinical follow-up.