ICU Chest Films > Lung Processes > Pulmonary Embolism > Radiographic Findings

Radiographic Findings in Pulmonary Embolism

Due to its relative lack of sensitivity, the chest x-ray in patients with suspected pulmonary embolism is usually relegated to the role of ruling out other disorders which may have a similar clinical presentation. The chest x-ray is also very useful when interpreting ventilation-perfusion scans. Though the majority of patients with pulmonary embolism in retrospect do have abnormalities on the chest x-ray, findings are usually too non-specific to be of diagnostic value. Without infarction there are few chest film signs of pulmonary emboli. These include discoid atelectasis, elevation of the hemidiaphragm, enlargement of the main pulmonary artery into what has been described as the shape of a "sausage" or a "knuckle" (Palla's sign), and pulmonary oligemia beyond the point of occlusion (Westermark's sign). Occasionally, pulmonary embolisms will cause infarction causing a unique constellation of radiographic signs. Multifocal consolidation of the affected lung may occur in 12 to 24 hours following the embolic event. A consolidation which begins at the pleural surface and is rounded centrally is called a Hamptom's Hump. These types of consolidation differ from pneumonia in that they lack air bronchograms. Up to 50% of patients with pulmonary embolism will also have ipsilateral or bilateral pulmonary effusions, although these are certainly nonspecific findings. Nevertheless, it is unusual for pulmonary infarctions to be diagnosed by chest radiography although infarctions are known to occur much more frequently. Presumably infarcts are confused with or indistinguishable from atelectasis or pneumonia. Despite the low sensitivity of these signs, the chest radiograph remains an important first step in the diagnosis of pulmonary embolism, primarily to exclude other causes of hypoxemia and to aid in the interpretation of the ventilation/perfusion scan.

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The red arrow points to a consolidation, known as Hamptom's hump,which is associated with pulmonary infarction.