• two layers: parietal and visceral
  • normal fluid < 50 ml
  • left atrium partially covered by pericardium
  • normal thickness < 2 mm
  • pericardial sinuses show normally small amount of fluid
  • oblique pericardial sinus behind left atrium (DD: bronchogenic cyst)
  • transverse pericardial sinus behind ascending aorta (DD: aortic dissection, lymphadenopathy)
  • superior pericardial recess lies posterior to ascending aorta