Chest radiograph signs of Pulmonary Embolism

Classic chest radiograph signs of pulmonary emboli include –

Signs of Pulmonary EmbolismFindings on X-Ray
1 ‘Westermark sign’ Regional oligaemia
2 ‘Palla sign’ Right descending pulmonary artery enlargement
3 ‘Fleishner sign’ Central pulmonary artery enlargement
4 ‘knuckle sign’ Abrupt pulmonary artery tapering

Westermark sign – regional oligaemia

Westermark sign is a sign that represents a focus of oligemia

  1. Dilation of the pulmonary arteries proximal to the embolus
  2. Collapse of the distal vasculature creating the appearance of a sharp cut off on chest radiography.
  3. Low sensitivity (11%) and high specificity (92%) for the diagnosis of pulmonary embolism

Palla sign – right descending pulmonary artery enlargement

Palla sign describes an enlarged right descending pulmonary artery which suggestive of an occlusion of a lobar or segmental pulmonary artery, or widespread occlusion of small arteries.

Fleischner sign – central pulmonary artery enlargement

Fleischner sign refers to a prominent central pulmonary artery that can be commonly caused either by pulmonary hypertension or by distension of the vessel by a large pulmonary embolus

Knuckle sign – abrupt pulmonary artery tapering

knuckle sign refers to the abrupt tapering or cutoff of a pulmonary artery secondary to a pulmonary embolus

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