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Figure 15d. CT and conventional angiographic evaluation of a scimitar syndrome diagnosed in a 29-year-old patient who presented with hemoptysis originating from the right lower lobe. (a) Transverse thin-section CT scan obtained at the level of the lower lobes shows numerous and abnormally dilated vascular structures within an area of ground-glass attenuation (arrowheads) in the right posterobasal segment and a large vascular structure (arrow) corresponding to the scimitar vein. (b) Hyperselective catheterization of the right inferior phrenic artery, obtained prior to embolization, demonstrates the abnormal systemic arterial supply to the right posterobasal segment (arrowhead). (c) Frontal MIP image generated from a focal spiral CT angiogram (5-mm collimation, pitch of 1.4, 30% iodinated contrast agent) of the lower lung zones provides an overall analysis of the scimitar vein (small ) draining into the inferior vena cava (large ) without stenosis at its distal portion. (d) Selective catheterization (frontal angiogram obtained during the hemodynamic evaluation of the scimitar syndrome) of the scimitar vein () confirms the absence of stenosis of the abnormal pulmonary venous drainage.