Fetal thoracic abnormalities: MR imaging.

Abstract

PURPOSE: To elucidate the appearance of fetal thoracic abnormalities at prenatal magnetic resonance (MR) imaging and determine whether MR imaging yields information additional to that obtained with ultrasonography (US). MATERIALS AND METHODS: US and MR imaging data from 83 MR examinations of 74 fetuses with thoracic abnormalities and confirmatory US performed within 1 week before MR imaging were compared with respect to resulting changes in patient counseling and/or care. Lung parenchyma and lesion signal intensities and vascularity, airway, esophagus, and diaphragm appearances were reviewed retrospectively on MR images. Student t tests and analyses of variance were performed. RESULTS: MR imaging yielded information additional to that acquired with US in 28 (38%) of 74 fetuses. The additional findings were confirmed in 19 of the 28 fetuses at postnatal follow-up; no follow-up data were available for the other nine fetuses. Thoracic MR information affected care with regard to six (8%) of 74 fetuses. Mean gestational age of 15 fetuses with lung signal intensity (SI) slightly lower than that of amniotic fluid (28.4 weeks +/- 6.8 [SD]) at T2-weighted MR imaging was significantly older than that of 18 fetuses with intermediate SI (21.3 weeks +/- 4.3) (P <.05). Mean SI of 13 congenital cystic adenomatoid malformations (CCAMs) and/or sequestrations (1.74 +/- 1.05) at T2-weighted MR imaging was significantly higher than that of the normal lungs of 33 fetuses (2.63 +/-.63) (P <.001). Among nine studies in which vessels were visualized in CCAMs and/or sequestrations, six involved a normal vascular branching pattern. Portions of the esophagus were seen in 31 (36%) of 85 fetuses. Nonvisualization of a major airway was not sufficient for diagnosis of pulmonary atresia. Visualization of a portion of the esophagus did not correlate with esophageal atresia. In all except one fetus, who had anhydramnios and pulmonary hypoplasia, and the fetuses with congenital diaphragmatic hernia, at least a portion of the diaphragm was visualized at MR imaging. CONCLUSION: MR imaging yields information additional to that yielded with US in fetuses with thoracic abnormalities.