Diagnostic utility of dynamic CT in tracheomalacia in COPD patients

BackgroundInvestigators have suggested a correlation of tracheomalacia with chronic inflammation and irritants, such as cigarette smoke. Recent advances in CT imaging provide an opportunity to non-invasively diagnose the condition with a high level of accuracy. Dynamic CT of the chest exhibits tracheal collapse with crescentic bowing of the posterior membranous trachea during expiration.Aim of the workTo determine the prevalence of tracheomalacia identified on computed tomography of the chest in patients clinically diagnosed with COPD.Subjects and methodsThirty COPD patients were included in the study and the diagnosis of COPD was based on lung function and reversibility test. The CT protocol focused on the central airways and included imaging during two phases of respiration. The percentage of luminal collapse was calculated by dividing the dynamic expiratory cross-sectional area by the end-inspiratory cross-sectional area and multiplying by 100. If luminal collapse is more than 50% the case is diagnosed as tracheomalacia.ResultsThis study showed that 20% (6 of 30) of COPD subjects showed evidence of tracheomalacia based on the criteria of a ⩾50% reduction in the cross-sectional trachea lumen area at end expiration. FEV1 and FEV1/FVC were statistically significant lower in subjects with tracheomalacia than those without tracheomalacia.ConclusionThe results of this study clarify that a significant subgroup of patients with a reported clinical diagnosis of COPD has features consistent with tracheomalacia on dynamic CT scanning of the chest. This indicates that tracheomalacia may be a hidden comorbidity in COPD.