Quantitative assessment of regional emphysema distribution in patients with chronic obstructive pulmonary disease (COPD)

Abstract

To compare objective and subjective assessment of the distribution of emphysema in unselected patients with chronic obstructive pulmonary disease (COPD). 167 patients were computed tomography (CT) scanned, and the relative area (RA-910) of emphysema in each CT slice was plotted against table position. The craniocaudal distribution was calculated as the slope of the regression line, and grouped as upper-lung-zone predominance (ULP), lower-lung-zone predominance (LLP), or mild/homogeneous distribution (MHE). CT scans were also classified as ULP, LLP, and MHE based on visual assessment of three high-resolution CT (HRCT) slices, and the leading pattern of emphysema was classified as centrilobular (CLE), paraseptal (PSE), panlobular (PLE), or no emphysema (NE). By objective classification, scans were divided into almost equal numbers of ULP, LLP, and MHE, whereas visual evaluation classified more scans as ULP (P<0.001) and very few as LLP (P<0.0001). In patients with CLE, 49% had ULP by objective classification, whereas LLP was the commonest leading pattern in PSE, PLE, and NE. We found significant discrepancies between the objective and subjective distributions of emphysema in various morphological patterns, which may be of clinical importance in, for instance, lung-volume-reduction surgery.