References

of symptoms and lung function impairment. Asthma attack is frequently associated with environmental or occupational exposure to allergen or dust and upper respiratory tract viral infection.

CT Findings

The most common CT findings of asthma are the thickening and narrowing of the medium-sized and small bronchi [5, 6] (Fig. 24.2). Other CT findings include mucoid impaction, cylindrical bronchiectasis, centrilobular small nodules, and multifocal and patchy areas of mosaic perfusion due to air trapping, emphysema, and rarely, cysts (Fig. 24.2).

CT–Pathology Comparisons

Thickening and narrowing of the bronchi on CT is related to airway inflammation. The bronchi are thickened by the combination of edema and an increase in the amount of smooth muscle and in the size of mucous glands. Recurrent inflammation and airway remodeling result in bronchiectasis. Multifocal and patchy areas of mosaic perfusion are due to air trapping caused by constrictive bronchiolitis [6]. Centrilobular small nodules reflect the presence of mucus stasis in the bronchioles and peribronchiolar inflammation. Emphysematous change is secondary to cicatricial peribronchial fibrosis and

cystic changes may result from overinflating distal to chronic inflammatory bronchiolitis.

Patient Prognosis

Environmental control and avoidance of occupational exposure to allergen is important for asthma control. Since asthma is a chronic airway inflammatory disorder, inhaled corticosteroids are the principal therapy, with the use of bronchodilator to improve the symptoms.

References

1.Grosse C, Grosse A. CT findings in diseases associated with pulmonary hypertension: a current review. Radiographics. 2010;30: 1753–77.

2.Rodrigo GJ, Rodrigo C, Hall JB. Acute asthma in adults: a review. Chest. 2004;125:1081–102.

3.King Jr TE. Overview of bronchiolitis. Clin Chest Med. 1993;14:607–10.

4.Roche WR. Inflammatory and structural changes in the small airways in bronchial asthma. Am J Respir Crit Care Med. 1998;157:S191–4.

5.Park CS, Muller NL, Worthy SA, Kim JS, Awadh N, Fitzgerald M. Airway obstruction in asthmatic and healthy individuals: inspiratory and expiratory thin-section CT findings. Radiology. 1997;203:361–7.

6.Silva CI, Colby TV, Muller NL. Asthma and associated conditions: high-resolution CT and pathologic findings. AJR Am J Roentgenol. 2004;183:817–24.

Definition

Please refer to section “Airway Disease (Bronchiectasis and Bronchiolectasis)” in Chap. 13.

bronchiectasis. Noninfectious causes include allergic bronchopulmonary aspergillosis and asthma. Also note section “Airway Disease (Bronchiectasis and Bronchiolectasis)” in Chap. 13.

Diseases Causing Bronchiectasis

and Bronchiolectasis

Diffuse form of bronchiectasis occurs in variety of genetic abnormalities, especially those with abnormal mucociliary clearance or structural abnormalities of the bronchus or bronchial wall (cystic fibrosis [Fig. 25.1], dyskinetic cilia syndrome, Williams–Campbell syndrome). Nontuberculous mycobacterial disease is the most common infectious causes of diffuse

Distribution

Please note section “Airway Disease (Bronchiectasis and Bronchiolectasis)” in Chap. 13.

Clinical Considerations

Please note section “Airway Disease (Bronchiectasis and Bronchiolectasis)” in Chap. 13.