Table 1 CT scoring system for parapneumonic effusions (maximum total score = 8)
Fluid densityPleural enhancementSubcostal tissue thickeningLoculation/effusion shape
Mean density <20 HU (Score 0)Absent (Score 0)Absent (Score 0)Simple: Concave medially, parallels chest wall (Score 0)
Present, <2 mm thick (Score 1)Present, <2 mm thick (Score 1)Loculated: convex medially or lobulated with separation of lobulations by >10 mm of fluid/thickening (Score 1)
Mean density >20 HU (Score 1)Present, >2 mm thick (Score 2)Present, >2 mm thick (Score 2)Incomplete multiloculation: lobulations separated by <10 mm of pleural thickness (Score 2)
Complete multiloculation: pockets of fluid separated by normal intervening pleura (Score 3)
  • HU, Hounsfield units.