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

Area of Science:

• Pulmonary Medicine
• Radiology
• Medical Imaging Analysis

Background:

• The Fleischner Society criteria provide global visual assessment for pulmonary emphysema on CT scans.
• Current criteria may group heterogeneous emphysema severities, potentially masking clinically significant differences.
• A need exists for more granular emphysema classification to better reflect disease heterogeneity.

Purpose of the Study:

• To propose and validate an extended emphysema classification system assessing each lung lobe separately.
• To evaluate the added information provided by this extended classification in general population cohorts.
• To compare lobar emphysema distribution between smokers and never-smokers.

Main Methods:

• Utilized low-dose chest CT data from 117 participants with emphysema in two population-based cohorts.
• Two independent readers performed an extended per-lobe classification and semi-quantitative overall severity assessment.
• Calculated an emphysema sum score and quantified inter-reader agreement using Krippendorff Alpha.

Main Results:

• The extended classification and sum score demonstrated substantial inter-reader agreement (alpha 0.79 and 0.85).
• Significant differences in emphysema sum scores were observed across mild, moderate, and severe categories, though ranges overlapped.
• Lobar emphysema distribution was homogenous in never-smokers but heterogeneous in current smokers, with upper-lobe predominance.

Conclusions:

• The proposed extended emphysema evaluation method provides additional clinically relevant information beyond the standard Fleischner criteria.
• Individuals within the same Fleischner category exhibit diverse emphysema sum scores, highlighting classification limitations.
• Lobar emphysema distribution patterns differ significantly between smoking groups, suggesting distinct disease progression.