Bronchiolitis obliterans on high-resolution ct: A pattern of mosaic oligemia

Objective: Bronchiolitis obliterans, when not associated with organizing intraalveolar pneumonia or extensive peribronchiolar fibrosis, is often difficult to distinguish clinically and radiographically from other forms of chronic obstructive pulmonary disease. The aim of this study was to demonstrate a pattern on high-resolution CT (HRCT) that could suggest this diagnosis. Materials and Methods: Two patients with a clinical diagnosis of bronchiolitis obliterans, moderate-to-severe obstruction on pulmonary function tests, and normal ehest radiography were studied with HRCT. Results: High-resolution CT of the patients with chronic bronchiolitis demonstrated a mosaic pattern of low attenuation probably corresponding to secondary lobules. Conclusion: We conclude that the low attenuation areas represent either air trapping or hypoxic vasoconstriction in secondary pulmonary lobules from obstruction of small airways. This pattern of mosaic oligemia was, until recently, only recognized with occlusive vascular disease and may suggest obstructive disease in the small airways.