Rationale: Although centrilobular emphysema (CLE) and paraseptal emphysema (PSE) are commonly identified on multidetector computed tomography (MDCT), little is known about the pathology associated with PSE compared with that of CLE.Objectives: To assess the pathological differences between PSE and CLE in chronic obstructive pulmonary disease (COPD).Methods: Air-inflated frozen lung specimens (n = 6) obtained from patients with severe COPD treated by lung transplantation were scanned with MDCT. Frozen tissue cores were taken from central (n = 8) and peripheral (n = 8) regions of each lung, scanned with micro-computed tomography (microCT), and processed for histology. The core locations were registered to the MDCT, and a percentage of PSE or CLE was assigned by radiologists to each of the regions. MicroCT scans were used to measure number and structural change of terminal bronchioles. Furthermore, microCT-based volume fractions of CLE and PSE allowed classifying cores into mild emphysema, CLE-dominant, and PSE-dominant.Measurements and Main Results: The percentages of PSE measured on MDCT and microCT were positively associated (P = 0.015). The number of terminal bronchioles per milliliter of lung and cross-sectional lumen area were significantly lower and wall area percentage was significantly higher in CLE-dominant regions compared with mild emphysema and PSE-dominant regions (all P < 0.05), whereas no difference was found between PSE-dominant and mild emphysema samples (all P > 0.5). Immunohistochemistry showed significantly higher infiltration of neutrophils (P = 0.002), but not of macrophages, CD4, CD8, or B cells, in PSE compared with CLE regions.Conclusions: The terminal bronchioles are relatively preserved, whereas neutrophilic inflammation is increased in PSE-dominant regions compared with CLE-dominant regions in patients with COPD.
Keywords: chronic obstructive pulmonary disease; immune cells; microCT; small airway disease; terminal bronchiole.