Quantitative Emphysema Distribution in Anatomic and Non-anatomic Lung Regions

Area of Science:

• Pulmonary Medicine
• Radiology
• Quantitative Imaging

Background:

• Emphysema distribution in chronic obstructive pulmonary disease (COPD) changes with disease severity.
• The specific involvement of the upper aspect of the lower lobe in emphysema progression remains unclear.

Purpose of the Study:

• To quantitatively assess regional emphysema distribution across all COPD severity stages.
• To compare emphysema distribution using anatomical (lobes) and non-anatomical (halves, core/rind) lung regions.

Main Methods:

• Quantitative analysis of 100 CT datasets for emphysema characteristics.
• Comparison of emphysema index, mean lung density, and 15th percentile values between different lung regions.
• Statistical comparison (t-test) of upper/lower lobes versus upper/lower halves, and core versus rind regions.

Main Results:

• In mild to moderate COPD (GOLD ≤ II), upper lobes showed significantly higher emphysema burden than upper halves.
• In severe COPD (GOLD III/IV), differences in emphysema characteristics between lobes and halves were not significant.
• A notable difference in emphysema distribution between lobar and half regions was observed in milder COPD, diminishing in more severe stages.

Conclusions:

• Lobar segmentation offers a more precise characterization of cranio-caudal emphysema distribution in early COPD stages (up to GOLD II).
• Non-anatomical regional analysis may be less effective in differentiating emphysema distribution in early disease compared to lobar segmentation.