Multimodality imaging of pulmonary infarction

• A plethora of pulmonary and systemic disorders, often associated with grave outcomes, may cause pulmonary infarction.
• A stereotypical infarct is a peripheral wedge shaped pleurally based opacity but imaging findings can be highly variable.
• Multimodality imaging is key to diagnosing the presence, aetiology and complications of pulmonary infarction.
• Multimodality imaging of pulmonary infarction together with any ancillary features often guide to early targeted treatment.
• CT remains the principal imaging modality with MRI increasingly used alongside nuclear medicine studies and ultrasound.

The impact of absent pulmonary arterial and venous flow on the pulmonary parenchyma depends on a host of factors. These include location of the occlusive insult, the speed at which the occlusion develops and the ability of the normal dual arterial supply to compensate through increased bronchial arterial flow. Pulmonary infarction occurs when oxygenation is cut off secondary to sudden occlusion with lack of recruitment of the dual supply arterial system. Thromboembolic disease is the commonest cause of such an insult but a whole range of disease processes intrinsic and extrinsic to the pulmonary arterial and venous lumen may also result in infarcts. Recognition of the presence of infarction can be challenging as imaging manifestations often differ from the classically described wedge shaped defect and a number of weighty causes need consideration. This review highlights aetiologies and imaging appearances of pulmonary infarction, utilising cases to illustrate the essential role of a multimodality imaging approach in order to arrive at the appropriate diagnosis.