Signs to help you recognize a PE on a CXR
Fleischner sign
- Local widening of a central pulmonary artery
- Caused by Pulmonary Hypertension (developed secondary to peripheral embolization) or very large pulmonary embolous (distention by clot)
- Seen most commonly in the setting of massive pulmonary embolism. It has a low sensitivity but high specificity.
Hampton hump
- Dome-shaped, segmentally distributed, pleural-based opacification
*While a pulmonary embolism is expected to result in a wedge-shaped infarction, the expected apex of this infarction may be spared because of collateral supply from the bronchial arterial circulation, leading to the characteristic rounded appearance*
- Opacification secondary to haemorrhage due to blood supply from bronchial arteries
- In cases of infarction, it takes months to resolve, and often leaves a linear scar
- If no infarction, Hampton hump will resolve, by "melting" --> keeps typical configuration but just gets smaller
Westermark sign
- Focal area of hyperlucency due to oligemia from either obstruction of the pulmonary artery or distal vasoconstriction
Knuckle sign
- Abrupt tapering or cutoff of a pulmonary artery
- Better visualised on CTPA than CXR.
- Often associated with the Fleischner sign
Palla sign
- Enlarged right descending pulmonary artery.
- When present with Westermark sign = occlusion of a lobar/segmental pulmonary artery OR widespread occlusion of small arteries
- Descending interlobar branch of the right pulmonary artery is enlarged, causing a "sausage" appearance towards right middle lobe of the CXR
Case numbers: 4108504, 498327
References:
Dahnert, W. (2008). Radiology Review Manual (6th Edition). Philadelphia: Lippincott Williams & Wilkins
Plain Film Signs in Pulmonary Embolism (with CT correlate), Kirwadi A, Bickle IC. http://www.eurorad.org/eurorad/case.php?id=7735 Eurorad case 7735
Worsley DF, Alavi A, Aronchick JM et-al. Chest radiographic findings in patients with acute pulmonary embolism: observations from the PIOPED Study. Radiology. 1993;189 (1): 133-6. Radiology (abstract) - Pubmed citation
Abbas A, St Joseph EV, Mansour OM et-al. Radiographic features of pulmonary embolism: Westermark and Palla signs. Postgrad Med J. 2014;90 (1065): 422-3. doi:10.1136/postgradmedj-2013-132000 - Pubmed citation
Hansell DM, Bankier AA, Macmahon H et-al. Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246 (3): 697-722. Radiology (full text) - doi:10.1148/radiol.2462070712 - Pubmed citation
Stein PD, Athanasoulis C, Greenspan RH, et al. Relation of plain chest radiographic findings to pulmonary arterial pressure and arterial blood oxygen levels in patients with acute pulmonary embolism. Am J Cardiol. 1992;69:394.
Fleischner FG. Roentgen diagnosis of pulmonary embolism. The Heart bulletin. 10: 104-7. Pubmed
Maizlin ZV, Cooperberg PL, Clement JJ, Vos PM, Coblentz CL. People behind exclusive eponyms of radiologic signs (Part II). Canadian Association of Radiologists journal = Journal l'Association canadienne des radiologistes. 61 (1): 44-53. doi:10.1016/j.carj.2009.10.011 - Pubmed
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