CT OF BRONCHIAL AND BRONCHIOLAR DISEASES

Computed tomography (CT) is useful in evaluating bronchial and bronchi olar abnormalities. Common bronchial and bronchiolar abnormalities inc lude bronchiectasis, asthma, bronchial obstruction, and various forms of bronchiolitis. Causes of bronchiectasis include cystic fibrosis, ch ildhood viral infection, allergic bronchopulmonary aspergillosis, and pulmonary fibrosis. On CT scans, cystic fibrosis may manifest with bro nchial wall thickening, bronchiectasis (usually cylindrical, with vari cose and cystic forms seen in advanced cases), and mucus plugs in the bronchi. Allergic bronchopulmonary aspergillosis is characterized by c entral, varicose or cystic bronchiectasis, predominantly in the upper lobes, with mucoid impaction in the bronchi. Traction bronchiectasis m ay be seen on CT scans of pulmonary fibrosis. Asthma is characterized by bronchial wall thickening due to inflammation. Bronchial dilatation and air trapping may also be seen. Bronchiolitis obliterans is manife sted by direct and indirect signs on CT scans; the former consist of c entrilobular branching structures and nodules, and the latter consist of bronchiectasis and bronchiolectasis, mosaic perfusion, and air trap ping. CT findings of bronchiolitis obliterans organizing pneumonia (al so known as cryptogenic organizing pneumonia) include air-space consol idation and nodules, with occasional bronchial dilatation and pleural effusions.