Congenital chest lesions: diagnosis and characterization with prenatal MR imaging.

PURPOSE: To evaluate prenatal magnetic resonance (MR) imaging for diagnosis of fetal chest masses and to determine if MR imaging provides information in addition to that of ultrasonography (US).
MATERIALS AND METHODS: Eighteen pregnant women were referred for MR imaging of possible fetal chest tumors seen at US (16 congenital cystic adenomatoid malformation [CCAM], two bronchopulmonary sequestration [BPS]). The presence, position, size, and characteristics of masses were determined and correlated with postnatal results.
RESULTS: The MR imaging diagnoses were three cases of congenital diaphragmatic hernia, nine of CCAM, two of BPS, and one each of foregut cyst, lung atresia, tracheal atresia, and bronchial stenosis. MR imaging results were in agreement with US results in nine fetuses and in disagreement in nine. MR imaging diagnoses were confirmed at surgery or autopsy in 17 fetuses. MR imaging results led to an error in diagnosis in one fetus with BPS.
CONCLUSION: Fetal chest masses had characteristic MR imaging appearances. MR imaging was accurate for distinguishing congenital diaphragmatic hernia from CCAM and was useful for less common diagnoses and determination of the origin of very large chest tumors. Prenatal diagnosis was changed in some patients owing to MR results and affected treatment and counseling of parents. MR imaging is a valuable adjunct to US for prenatal diagnosis of fetal chest masses.