Typical findings for bronchiolitis in high resolution computed tomography.

High resolution computed tomography is a diagnostic modality of choice in imaging of interstitial lung diseases. HRCT enables visualization of the pathological findings invisible on plain radiographs and their evaluation at the level of the pulmonary lobule. The aim of the study was evaluation of typical HRCT findings in patients with bronchiolitis, and assessment of their usefulness in differential diagnosis. Tree in bud is a typical sign seen on HRCT sections in patients with bronchiolitis, resulting from filling the small centrilobular bronchioles with puss, mucus, granulomas or inflammatory cells. Material filling the bronchioles causes their obstruction resulting in the presence of air-trapping, visible on expiratory sections. Thickening of the bronchiolar walls and dilatation of the small bronchioles is also very often seen. Ground glass opacities and small nodules are also seen in some patients with bronchiolitis.