Exercise: Airway Disease

EXERCISE 4-5. AIRWAY DISEASE

4-10. The most accurate description of this chest radi-ograph (Figure 4-28 A,B) is

A.         decreased lung volume.

B.         diffuse thickening of the bronchial walls.

C.         cardiomegaly.

D.         pleural effusion.

E.          mediastinal shift.

Radiologic Findings

4-10. In this case, the most prominent radiographic finding in Figure 4-28 A is coarse thickening of the bron-chovascular bundles as they radiate from the hila. Thickened bronchial walls may be identified as tram-track lines, which refers to the appearance of the nearly parallel walls of bronchi oriented longitudinally. Care-ful inspection shows that these are present throughout both lungs and are located near the hila. Bronchial walls also project as ring-shaped opacities near the hila whenthe bronchus is seen end-on. Both of these structures represent the thick walls of dilated bronchi (bronchiec-tasis). The hila themselves are slightly enlarged as a re-sult of a combination of enlarged hilar lymph nodes and mild pulmonary arterial hypertension. The lung volume is increased. The anterior clear space (retroster-nal area) is larger and more radiolucent than normal. (B is the correct answer to Question 4-10).

Discussion

The cause of this patient’s bronchiectasis is cystic fibrosis. The mucus in patients with cystic fibrosis is thickened, and these patients do not have normal tracheobronchial clear-ance. This abnormal clearance may cause mucoid impaction, and atelectasis and pneumonia are frequent complications. Bronchiectasis can also occur as a result of pneumonia in pa-tients without cystic fibrosis. In patients with pneumonia, the bronchiectasis is more likely to be confined to a single lobe, often a lower lobe. Bronchiectasis is divided into three groups: cylindrical, fusiform (or varicose), and saccular (or cystic). These three groups not only describe the appearance of the abnormal bronchi, but also give an indication as to its severity. Cylindrical bronchiectasis (Figure 4-29 A), the mildest form, is reversible and appears as thick-walled bronchi that fail to taper normally. The more severe forms, fusiform and saccular, are irreversible. Fusiform (Figure 4-29bronchiectasis has a beaded appearance, whereas the bronchi in saccular (Figure 4-29 C) bronchiectasis end with clubbed, cystic areas. If the severe forms are localized, surgi-cal resection may be curative. Medical therapy with bron-chodilator and, when necessary, antibiotics is used when surgery is not indicated.

CT is the method of choice for determining the presence and extent of bronchiectasis. When the bronchus is perpen-dicular to the CT plane of section, bronchiectasis is identified as a ring shadow adjacent to an opaque circle. The ring repre-sents the thickened dilated bronchial walls. The opaque circle represents the pulmonary artery adjacent to the dilated bronchus. This is called the “signet ring” sign (Figure 4-30). Bronchi and arteries travel together throughout the lung and are normally of the same caliber.