[The role of pulmonary function and computer-assisted tomography imaging in COPD clinics]

Chronic obstructive pulmonary disease (COPD) is characterized by the presence of airflow limitation caused by a loss of elastic recoil of the lung and/or small airway remodeling. Emphysema is the major pathological lesion in COPD, defined as the abnormal and permanent enlargement of distal airspaces and destruction of alveolar walls. Emphysema correlates most closely with a loss of elastic recoil of the lung and is associated with both airflow limitation and loss of diffusion capacity, while the airway component contributes mainly to airflow limitation. Pulmonary functions reflect these pathological changes and are standard indices for "lung physiological abilities", so that these seem to be appropriate to evaluate the general lung status in vivo. In CT, emphysema is identified as low attenuation and airway wall thickening, and airway lumen narrowing can also be quantified. These CT indices shows the morphological changes/abnormalities that correspond to pathological changes. Thus, CT indices reflect pathological abnormality more precisely and have several advantages over pulmonary functions because those can give us regional information that pulmonary function tests cannot offer. Through the rigorous investigation of COPD pathophysiology using these CT indices, some aspects of the COPD course, such as emphysema progression, and the relationship between COPD pathophysiology and systemic manifestations are becoming clear. (Review).