both contributed equally to this article.Objective: To evaluate dual-energy CT (DECT) findings of pulmonary ischaemic-reperfusion injury (PIRI) and its pathophysiological correlation in the canine model. Methods: A PIRI model was established in 11 canines, utilizing closed pectoral balloon occlusion. Two control canines were also included. For the PIRI model, the left pulmonary artery was occluded with a balloon, which was deflated and removed after 2 h. DECT was performed before, during occlusion and at 2, 3 and 4 h thereafter and was utilized to construct pulmonary perfusion maps. Immediately after the CT scan at the fourth hour post reperfusion, the canines were sacrificed, and lung specimens were harvested for pathological analysis. CT findings, pulmonary artery pressure and blood gas results were then analysed. Results: Data at every time point were available for 10 animals (experimental group, n 5 8; control group, n 5 2).Quantitative measurements from DECT pulmonary perfusion maps found iodine attenuation values of the left lung to be the lowest at 2 h post embolization and the highest at 1 h post reperfusion. In the contralateral lung, perfusion values also peaked at 1 h post reperfusion. Continuous hypoxia and acid-based disorders were observed during PIRI, and comprehensive analysis showed physiological changes to be worst at 3 h post reperfusion. Conclusion: DECT pulmonary perfusion mapping demonstrated pulmonary perfusion of the bilateral lungs to be the greatest at 1 h post reperfusion. These CT findings corresponded with pathophysiological changes. Advances in knowledge: DECT pulmonary perfusion mapping can be used to evaluate lung ischaemiareperfusion injury.Ischaemia-reperfusion injury (IRI) occurs under a variety of clinical conditions, including lung and/or cardiac transplantation, cardiopulmonary bypass, pulmonary resection, re-expansion pulmonary oedema, shock, cardiopulmonary resuscitation and pulmonary embolism.1-3 Pulmonary embolism is a common cause of pulmonary IRI (PIRI), and the incidence of pulmonary embolism is increasing 4,5 with a mortality rate of up to 30%. 6 With timely identification and treatment of pulmonary embolism, mortality rates can be reduced to ,10%.7 However, reperfusion after treatment for lung ischaemia can also cause serious complications, such as haemorrhage and pulmonary oedema.8 Therefore, it is important to understand both the pathophysiological and imaging appearances of pulmonary IRI. Lung transplantation is also a common cause for PIRI following pulmonary arterial occlusion. Currently, the incidence of PIRI following transplantation is estimated at up to 25%. Post transplantation, PIRI can lead to insufficiency of the primary lung graft, delayed graft function, acute or chronic rejection (e.g. pulmonary oedema and acute respiratory failure), and increased early post-operative mortality and graft failure. 9,10 CT is currently the predominant modality for the imaging assessment of thoracic disorders, including PIRI. Dual-energy CT (DECT) allows simultaneous ac...