[Morphological analysis of the secondary pulmonary lobule with inflated fixed lung specimen. Part 2: Three-dimensional measurement of intralobular structures]

In this study, we made three-dimensional measurements of intralobular structures in normal and diseased conditions using inflated fixed lung specimens. Lung blocks obtained from the subpleural and hilar areas were cut into slices 0.5 mm thick and radiographed. After tracing intralobular structures on these radiograms, trace data were transferred to a three-dimensional computer system and three-dimensional measurement was made. Autopsied lungs with diseased conditions including idiopathic pulmonary fibrosis, aging lung and panacinar emphysema were also used. The distance from the tip of the intralobular arteriole accompanying the terminal bronchiole to the corresponding lobular border was 2.4 +/- 0.5 mm in the subpleural area and 2.1 +/- 0.5 mm in the hilar area. The corresponding values in emphysema, aging lung and idiopathic pulmonary fibrosis were 4.1 +/- 0.6, 3.4 +/- 0.4 and 1.4 +/- 0.2 mm, respectively. In most of the lobules, the volume ranged from 300 to 600 mm3 and was closely related in linear fashion with the number of terminal bronchioles. Branching angles of the pulmonary artery in the lobule ranged from 80 to 90 degrees, and there was no relationship to the pattern of branching. This information about the arrangement of pulmonary lobular structures in normal and diseased conditions will help in the interpretation of HRCT images of the lung.