Computed tomographic imaging of bronchiolar disorders.

The bronchiolitides can be categorized broadly as constrictive or proliferative, each with characteristic CT features. The cardinal CT signs of constrictive bronchiolitis are mosaic perfusion, enhanced on expiratory CT scan and variably associated with bronchiectasis and, less frequently, centrilobular branching structures. These features are common to postinfective bronchiolitis, bronchiolitis associated with collagen vascular disease, obliterative bronchiolitis following lung transplantation, and bronchiolitis following inhalation of toxic fumes and consumption of Sauropus androgynus. Proliferative bronchiolitis manifests on CT scan as patchy bilateral consolidation, variably associated with nodular abnormalities. The CT appearances of other rare bronchiolitides are discussed here including diffuse panbronchiolitis, follicular bronchiolitis, and respiratory bronchiolitis-associated interstitial lung disease.