Adult male smoker; follow-up CT.
Three patterns of emphysema:
1. Centrilobular with central arteries seen within centers of hypodense areas; peripheral sub-pleural areas are spared.
2. Paraseptal: involving sub-pleural and sub-fissural areas. One subpleural raw is seen mimicking one raw of blocks.
3. Panlobular: uniform destruction of pulmonary architecture.