The Role of Chest Computed Tomography in the Evaluation and Management of the Patient with Chronic Obstructive Pulmonary Disease

To facilitate comparisons between individuals, a useful measure known as Pi 10 takes advantage of the known linear relationship between the square root of the airway wall area and the internal perimeter of the airway (23); it represents the square root of the wall area lor a hypothetical airway with an internal perimeter of 10 mm. This measure, in combination with quantitative emphysema and air trapping measurements, has been shown to be a useful predictor of the presence of COPD on lung cancer screening scans (24). [...]the reproducibility, clinical validity, and ease of use of airway measurements can be further demonstrated, these quantitative methods are primarily limited to the research arena at this time; qualitative visual inspection of airways, including assessment of bronchial wall thickening, bronchiectasis, and expiratory central airway collapse, remains the standard in routine clinical practice. [...]although assessing symptoms in smokers clearly does not require a CT scan, if one is available, clinicians should be aware that even among patients without spirometrically defined COPD, emphysema and airway wall thickening can be associated with increased respiratory symptoms and poorer health status. In a study of current and former smokers, central airway collapse greater than 50% on expiration was associated with a higher frequency of respiratory exacerbations (56). [...]a ratio of the pulmonary artery diameter to the aorta diameter greater than 1 has also been demonstrated to be a strong and independent predictor of severe exacerbations (57), even when adjusted for lung function and prior history of exacerbations. [...]chest CT scans performed in patients with COPD for noncardiac reasons, such as lung cancer screening or pulmonary embolism exclusion, provide an opportunity to evaluate coronary atherosclerosis.