CT-based emphysema characterization per lobe: A proof of concept

Purpose: The Fleischner society criteria are global criteria to visually evaluate and classify pulmonary emphysema on CT. It may group heterogeneous disease severity within the same category, potentially obscuring clinically relevant differences in emphysema severity. This proof-of-concept study proposes to split emphysema into more categories and to assess each lobe separately, and applies this to two general population-based cohort samples to assess what information such an extension adds. Method: From a consecutive sample in two general population-based cohorts with low-dose chest CT, 117 par-ticipants with more than a trace of emphysema were included. Two independent readers performed an extended per-lobe classification and assessed overall severity semi-quantitatively. An emphysema sum score was deter-mined by adding the severity score of all lobes. Inter-reader agreement was quantified with Krippendorff Alpha. Results: Based on Fleischner society criteria, 69 cases had mild to severe centrilobular emphysema, and 90 cases had mild or moderate paraseptal emphysema (42 had both types of emphysema). The emphysema sum score was significantly different between mild (10.7 +/- 4.3, range 2-22), moderate (20.1 +/- 3.1, range: 15-24), and severe emphysema (23.6 +/- 3.4, range: 17-28, p < 0.001), but ranges showed significant overlap. Inter-reader agree-ment for the extended classification and sum score was substantial (alpha 0.79 and 0.85, respectively). Distri-bution was homogenous across lobes in never-smokers, yet heterogenous in current smokers, with upper-lobe predominance. Conclusions: The proposed emphysema evaluation method adds information to the original Fleischner society classification. Individuals in the same Fleischner category have diverse emphysema sum scores, and lobar emphysema distribution differs between smoking groups.

Automated summary

This study proposes a method to evaluate emphysema by splitting it into more categories and assessing each lobe separately, which adds information to the original Fleischner society classification. Individuals in the same Fleischner category have different emphysema sum scores, and the distribution of emphysema in lobes differs between smokers and non-smokers.