Fig. 4
From: Diffuse smoking-related lung diseases: insights from a radiologic-pathologic correlation
Subtypes of CLE according to the Fleischner Society guidelines on HRCT. Axial images in 3 smokers show a trace CLE, with minimal centrilobular lucencies occupying less than 0.5% of a lung zone (arrows); b mild CLE, defined as scattered centrilobular lucencies affecting 0.5% to 5% of a lung zone; and c moderate CLE, with numerous centrilobular lucencies occupying more than 5% of any lung zone