Chest Imaging

Tracheomalacia

abnormal softening of the supportive cartilage rings producing abnormal tracheal flaccidity. This disorder may also involve the central bronchi and be called bronchomalacia. The increased flaccidity of the major airways leads to collapse during forced expiration. The primary type of the disease is rare, observed only in children. In most cases, particularly in adults, tracheomalacia is secondary to recurrent infections, chronic obstructive pulmonary disease, relapsing polychondritis, intubation, or trauma. Patients present clinically with wheezing and shortness of breath. At fibreoptic bronchoscopy, excessive collapse of the airways is noted during a voluntary cough.

Tracheomalacia can be diagnosed fluoroscopically by observing changes in tracheal dimension between inspiration and expiration. Electron beam CT has proven highly sensitive and quantitative by providing a means of precise measurement of the tracheal dimensions throughout the respiratory cycle. On CT scans, tracheomalacia is considered to be present if, during the respiratory cycle, any tracheal segment undergoes a reduction in its cross-sectional area of 50% or more from its maximum. Coronal and sagittal reconstruction images permit definition of the extent of tracheal abnormalities. Viewing in a cine display of CT images allows dynamic study that may help in identifying abnormalities of the trachea calibre which can be missed on static images.

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