Figure 1. Deep vein thrombosis of the left popliteal vein in a 54-year-old woman with unilateral leg swelling, later confirmed by ultrasound. (a) CT axial image at knee level shows non-opacification of the left popliteal vein (arrow). The right popliteal vein is normal (arrow head). (b) CT axial image 3.0 cm caudal to (a) shows an intraluminal filling defect of the left popliteal vein without expansion (arrow).