Quantitative imaging of chronic obstructive pulmonary disease—moving towards clinical application

COPD is characterized by progressive, non-reversible airflow limitation, associated with an enhanced chronic inflammatory pulmonary response. It is comprised by a mixture of small airways disease (obstructive bronchiolitis) and parenchymal destruction (emphysema). In addition, large airways inflammation (chronic bronchitis) is also part of the spectrum of COPD. The relative contributions of these components vary substantially, and may affect clinical presentation, frequency of exacerbations, prognosis, and therapeutic response. COPD is strongly related to smoking. It has emerged as the third leading cause of death in the United States, the only one that has been steadily rising in the past decades. The diagnosis of COPD is based on clinical grounds and spirometric [pulmonary function testing (PFT)] evidence of non-reversible obstruction. Classification of severity relies on spirometric parameters, and worsening obstruction correlates with increasing morbidity and mortality (1,2). According to the GOLD practice guideline, imaging does not play a substantial role in the diagnosis of COPD (1,2).