Clinical correlations of computed tomography imaging in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease is a complex disease with heterogeneous presentation, progression, and structural abnormality that is currently graded solely on clinical and physiologic parameters. Thoracic computed tomography imaging holds promise for phenotyping in chronic obstructive pulmonary disease, but despite increasing availability, this methodology has yet to be incorporated into clinical guidelines or routine clinical practice. However, the unique clinical implications of emphysema and airways disease are becoming clearer. Emphysema has a strong association with more rapid disease progression and mortality. Airways disease has a strong relationship with symptoms and health status. It is hoped that future refinement of emphysema assessment allowing for quantitative subtyping will also increase our ability to define clinically meaningful subgroups, as will development of methodologies to assess airways disease and, in particular, small airways through inspiratory/expiratory image registration techniques. Most important, however, is the need for longitudinal data, in not only observational but also therapeutic settings, such that the impact of interventions on radiographically defined phenotypes can be assessed.