Physiologic and Quantitative Computed Tomography Differences between Centrilobular and Panlobular Emphysema in Copd.

BACKGROUND The purpose was to define the differences between centrilobular (CLE) and panlobular emphysema (PLE) phenotypes in cigarette smokers with COPD by a combined qualitative-quantitative computed tomography (CT) analysis. METHODS Chest CT scans of 116 cigarette smokers were visually scored by 22 chest radiologists and 29 pulmonologists in a single setting for the predominant emphysema phenotype (e.g. CLE or PLE) and automatically quantified for emphysema{% low attenuation area (LAA) ≤ -950 HU - %LAAinsp-950, gas trapping extent and bronchial metrics{wall area % for segmental (%WAsegm) and subsegmental (%WAsubsegm) bronchi}. These quantitative CT indexes were compared and related to FEV1, FEV1/FVC, and smoking history as stratified for emphysema phenotype. RESULTS Although more frequent than CLE in GOLD stages 3 and 4 (p = 0.01), PLE was also scored in 38.2% of combined GOLD stages 1 and 2. PLE was positively associated with %LAAinsp-950 (OR = 1.18, 95% CI: 1.12 to 1.27, β coefficient = 0.17, p = <0.0001) and negatively associated with pack-years of smoking (OR = 0.97, 95% CI: 0.95 to 0.99, β coefficient = -0.02, p = 0.03). Both %WAsegm and %WAsubsegm were more strongly associated with FEV1% (R2 = 0.6 for both measures, p< 0.001) in CLE as compared to PLE (R2= 0.15, p = 0.02; R2 = 0.26, p< 0.001). CONCLUSIONS PLE likely represents a more advanced phase of emphysema, which may also occur in earlier COPD stages and show different interplay with airway disease as compared to CLE.