Prenatal evaluation of functional pulmonary hypoplasia via fetal magnetic resonance imaging.

Objective: The purpose of this study was to retrospectively examine the use of lung-to-liver signal intensity ratio (LLSIR) on T2-weighted images to predict functional pulmonary hypoplasia.

Methods: The subjects of this study were pregnant women who underwent magnetic resonance imaging (MRI). Patients who required nitric oxide inhalation and those who died from respiratory disorders were classified as having functional pulmonary hypoplasia (FPH). All other cases were presented as the control group. We retrospectively analyzed MRI and perinatal data. LLSIR was defined as the ratio of lung signal intensity to liver signal intensity. We examined the relationship between LLSIR and gestational age, compared the LLSIRs in the two groups, and calculated the best cut-off value of the LLSIR to predict FPH.

Results: One hundred and ninety-one patients were eligible for this study, and 12 cases were classified as having FPH. In the control group, LLSIR increased with age (r = 0.383, p < 0.001). We used the observed/expected LLSIR (o/e LLSIR), which was the ratio of obtained LLSIR to expected LLSIR calculated by the regression line to correct the effect of gestational age. In the FHP group, o/e LLSIR was significantly lower than in the control group (p < 0.001). A receiver operating characteristic curve analysis showed that cases with o/e LLSIR above 0.85 were less likely to cause FPH.

Conclusions: Low o/e LLSIR might reflect the histological characteristics of hypoplastic lung structures. O/e LLSIR seems to be a useful MRI parameter for screening FPH.