Bronchopulmonary and neurenteric forms of foregut anomalies. Imaging for diagnosis and management

Abstract

Bronchopulmonary foregut malformations encompass a great variety of anomalies that may arise from abnormal differentiation of the respiratory and alimentary tracts, abnormal separation of the two systems, or abnormal development of blood supply, perhaps singly or in combination, during early embryogenesis. The pulmonary and neurenteric forms share the common features of a pulmonary parenchymal opacification and/or intrathoracic mass, with the addition of vertebral anomalies in the instance of the neurenteric malformations. Plain radiographs serve as the starting point for diagnostic evaluation and sometimes are all that is needed; more often, though, the plain film findings suggest which road to follow in further imaging. No single imaging approach can be advocated for all patients. The lesion may be found initially, for example, on prenatal sonography. Ultrasonography also can establish the cystic nature of a mass and may help define vascular supply, although it cannot yet be said to have supplanted angiography's role in evaluating suspected sequestrations. For most intramediastinal or intrapulmonary masses without associated vertebral anomalies, CT will satisfactorily establish the cystic nature and should afford a reasonably confident preoperative diagnosis of bronchogenic cysts or type 1 or 2 cystic adenomatoid malformations. Type 3 cystic adenomatoid malformation, because of its relatively "solid" imaging characteristics, may not be diagnosed confidently by preoperative imaging. The finding of vertebral anomalies associated with a mediastinal mass especially warrants MR imaging to define intraspinal involvement. However, the association of vertebral or rib anomalies with apparent unilateral pulmonary agenesis or hypoplasia arouses suspicion of a bronchopulmonary foregut malformation that communicates with the gastrointestinal tract, and this uncommon situation calls for a barium examination. Radionuclide scintigraphy has an ancillary role in assessing foregut anomalies, but many findings from scintigraphy are relatively nonspecific and anatomic definition is poor. Scintigraphy may yield supportive information in cases of sequestration that have inconclusive findings as determined by plain radiographs and CT.