CT can visualize to 8 generation branches

Components include airway and arterial wall and central lymphatics

B/A > 1 seen in elderly (> 65 years old) or those living at high altitude (due to mild hypoxia that dilates bronchi and causes vasoconstriction)

B/A > 1.5 indicative of bronchiectasis

Acute bronchitis usually secondary to viral upper respiratory infection; chronic bronchitis due to inhaled irritants (cigarette smoke and air pollution)

CT insensitive, nonspecific findings of smooth bronchial wall thickening, narrowed lumen, mucus-filled airway

Reactive airways disease

Heterogeneous distribution in lung

Affects mainly small and medium-sized bronchi

Degree of bronchial wall thickening correlates with severity of airflow obstruction

Recurrent aspiration typically in elderly with neurologic disorders, dementia, or swallowing disorder

Gravity-dependent opacities

Consolidation and interstitial fibrosis centered on airways

Smooth bronchovascular bundle thickening due to peribronchovascular edema

Usually seen with associated findings: Septal thickening, cardiomegaly, pleural effusions

Integrity of bronchial wall dependent on normal immune system, normal structural integrity of airways (normal cartilage), and normal ciliary function

Bronchiectasis most commonly involves medium-sized bronchi of 4th-9th generations

Bronchi diameter larger than adjacent pulmonary artery: Cylindrical to saccular morphology

Focal or diffuse; when confined to 1 lobe, usually postinfectious or secondary to aspiration

Bronchial wall thickening may be absent even with dilatation

Perilymphatic nodules (granulomas) along axial interstitium

Often associated with septal and subpleural nodules

Bronchial wall thickening earliest finding, precedes development of bronchiectasis

Leads to diffuse bronchiectasis, usually more severe in upper lobes

Hypersensitivity reaction to Aspergillus fumigatus in asthmatics or cystic fibrosis

Central bronchiectasis, usually more severe in upper lobes

Strongly associated with smoking

Bronchocentric nodules evolving into cysts in upper and mid lung zones

Chronic granulomatous lung disease caused by inhalation of organic or chemical antigens

Chronic disease leads to fibrosis, usually centered on airways

Clinicopathological entity characterized by polypoid plugs of granulation tissue within airspaces

Most common pattern is multiple alveolar opacities (90%) centered on airways

Air-bronchograms common, often dilated

Other patterns: Multiple pulmonary nodules (may have air-bronchograms), solitary mass, perilobular pattern, reverse halo sign

May be either non-Hodgkin or Hodgkin

Multifocal masses centered on airways with air-bronchograms

Masses are usually nonobstructive

Typically adenocarcinomas

Nodular or beaded thickening of bronchovascular bundles

Frequency of involvement: Axial (75%) > axial + peripheral (20%) > peripheral (5%)

Spectrum of lymphoproliferative disorder

Ground-glass opacities, centrilobular nodules, and thin-walled cysts

Findings centered on lymphatic pathways: Peribronchovascular, septa, and pleura

AIDS-related neoplasm with propensity to involve skin, lymph nodes, GI tract, and lungs

Nodular perihilar thickening of bronchovascular bundles

Due to human papilloma virus, < 1% seed lung

Multiple solid or cavitated nodules centered on airways

Tracheobronchial most common form

Focal or diffuse thickening of airway wall with intraluminal nodules and submucosal foci of calcification