Previously, bronchography and bronchoscopy were recommended as part of the evaluation of CBA. However, these were not always diagnostic, and often patients ended up with surgical resections because of inability to diagnose these lesions by imaging, airway evaluation, or biopsy. Current-generation CT scanners provide a detailed sequential cross-sectional view of abnormal airways and also detect localized air trapping and hyperlucency, which is part of the diagnostic criteria for CBA. CT scan with contrast also helps rule out anomalies such as bronchopulmonary sequestration or bronchogenic cyst, which are differentials for CBA. Allergic bronchopulmonary aspergillosis results in mucoceles from mucoid impaction of dilated bronchi and is another differential for CBA. However, allergic bronchopulmonary aspergillosis can be differentiated from CBA by the presence of associated abnormalities in the lung, including central bronchiectasis, bronchial wall thickening, fleeting alveolar opacities, and tree-in-bud opacities.