Panbronchitis most commonly occurs in the middle-aged Asian population. On high-resolution CT, centrilobular opacities with branching lines (tree-in-bud pattern), bronchiolectasis, and bronchiectasis are seen.

CT findings in bronchitis are divided into direct and indirect signs:

• direct: bronchial wall thickening by inflammatory cells results in centrilobular nodules in the form of V and Y shaped patterns; bronchiolectasis in chronic forms of bronchiolitis seen in the pleural surface
• Indirect sign: mosaic attenuation with air trapping; air trapping is usually seen, but in diffuse cases, the mosaic attenuation may not be appreciated.

Types of bronchitis

• inflammatory, which includes infectious, hypersensitivity pneumonitis, respiratory bronchitis, follicular, panbronchitis, and bronchiectasis
• constrictive fibrotic type