A pericardial effusion is characterised by build up of fluid in the pericardial space (a normal pericardiac sac contains approximately 30 - 50 mls of fluid).

Causes

There are many including

* idiopathic
* inflammatory
o post myocardial infarction (Dressler syndrome)
o connective tissue disorders
* infectious
*
o viral
o bacterial
o tuberculosis
* post surgical / trauma
* radiotherapy
* malignancy
* metabolic
o hypothyroidism 3

Radiographic features

Plain film (CXR)

* a very small pericardial effusion can be occult on plain film
* there can be globular enlargement of the cardiac shadow giving a "water bottle" configuration (see case 2)
* lateral CXR may show an "Oreo Cookie Sign" : a vertical lucent line directly behind sternum (epicardial fat), behind this a vertical opaque line (pericardial fluid) and behind this a vertical lucent line (pericardial fat).
* widening of the subcarinal angle without other evidence of left atrial enlargement may be an indirect clue 2

Differential diagnoses

* haemopericardium : has higher attenuation on CT and often a different clinical context.
* cardiomegaly : can sometimes mimic an effusion

Pericardial effusion Modality: CT

Pericardial effusion Modality: X-Ray

Pericardial effusion Modality: X-Ray

Article Author : Dr Frank Gaillard, Radiopaedia

References

* 1. Lin Eugene, Kavita Garg, Edward Escott et al. Practical Differential Diagnosis in CT and MRI. Thieme, 2008. ISBN: 1588906558, 9781588906557.
* 2. J T Chen et.al. Widening of the subcarinal angle by pericardial effusion, American Journal of Roentgenology, Vol 139, Issue 5, 883-887; 1982
* 3. Stephen Arthur et.al, Hypothyroidism presenting with recurrent pericardial tamponade, BMJ Case Reports 2009; doi:10.1136/bcr.03.2009.1674