Ventilation-perfusion mismatch due to obstruction of pulmonary vein

A lobar perfusion defect in the presence of a normal arterial phase in the pulmonary angiogram may be due to stasis secondary to compression of a pulmonary vein by a hilar or perihilar mass. In this report we present a patient with metastasis to the right lung and hilum by malignant melanoma. A lobar perfusion defect was present in an area of lung tht appeared normal by radiograph. This defect was shown to be due to stagnating blood flow reflected by delayed intense capillary phase in that lobe and late opacification of the corresponding draining vein.