Tracheobronchomalacia: Evolving role of dynamic multislice helical CT

Tracheobronchomalacia (TBM) is a condition that is characterized by excessive airway collapsibility caused by weakness of the airway walls and supporting cartilage [1-5]. TBM may arise congenitally from disorders associated with impaired cartilage maturation or may be acquired in the setting of prior intubation, trauma, infection, long-standing extrinsic air-way compression, or chronic inflammation [1]. Abnormal flaccidity of the airway in TBM results in an inefficient coughing mechanism, with resultant difficulty clearing secretions, which may lead to recurrent infections and bronchiectasis [1]. Although TBM has been increasingly recognized as an important cause of chronic respiratory symptoms in recent years, it is still thought to represent a relatively underdiagnosed condition. Studies supporting this assertion include bronchoscopy series in which TBM has been found in 5% to 23% of all cases [3,6] and autopsy series in which pathologic changes of TBM have been reported in up to 20% of cases [2]. In one recent bronchoscopic series of nonsmoking patients evaluated for chronic cough, TBM was the causative etiology in 14% of cases [7]. This article describes the various methods for diagnosing TBM and discusses their relative merits and limitations. A special emphasis is placed on the evolving role of dynamic multislice helical CT for diagnosing TBM. The role of this method for aiding the selection of patients for interventional therapeutic measures, such as stent placement and tracheoplasty procedures, is also discussed.