ACUTE EXUDATIVE PHASE

• First week
• First findings > 12 hours after insult
• Patchy alveolar infiltrates
  • bilateral
  • gravity dependent, both central and peripheral
  • costophrenic angles are spared
  • air-bronchograms
  • Kerley lines are uncommon
• Infiltrates coalesce to large dense air-space bilateral shadows

FIBROTIC PHASE

• Begins as early as in the second week
• Coarse reticular interstitial pattern, later fibrosis