Congenital lung lesions: prenatal MRI and postnatal findings

Background Congenital lung lesions refer to a spectrum of malformations and developmental abnormalities of the foregut, pulmonary airways and vasculature. These lesions range from small, asymptomatic to large space-occupying masses that can increase risk of fetal death and respiratory compromise after birth. Prenatal sonography has been used for routine screening in pregnancy. The advent of prenatal magnetic resonance imaging leads to complementary use in the diagnosis of fetal anomalies, including in fetuses with congenital lung lesions. Objective To determine whether fetal MRI can differentiate congenital lung lesions by comparing prenatal diagnosis with postnatal imaging and pathology. Materials and methods In a 4-year period, 76 fetuses with suspected lung lesions were referred for fetal MRI. We retrospectively reviewed the MR exams and assigned a specific diagnosis based on predetermined criteria. We then compared the prenatal diagnosis to postnatal imaging and pathology. Results Of 76 cases, 7 were excluded because of an alternative diagnosis. Of the 69 remaining patients, 3 died and 13 were lost to follow-up. Among the 53 patients, there were 56 lung lesions. Four of these lesions were difficult to diagnose because of size and location. Based on imaging records we gave the remaining 52 lesions a specific prenatal diagnosis: 28 congenital pulmonary airway malformations (CPAM), 4 bronchopulmonary sequestrations (BPS), 9 cases of overinflation, 9 hybrid lesions and 2 bronchogenic cysts. The prenatal diagnosis was concordant with postnatal evaluation in 51 of the 52 lung lesions. One fetus given the diagnosis of CPAM prenatally was diagnosed with a hybrid lesion postnatally. Conclusion Prenatal MRI is highly accurate in defining congenital lung anomalies. When fetal MRI findings suggest a specific diagnosis, postnatal findings confirmed the prenatal MRI diagnosis in 98% of cases.