(Case 1). 1a CT thorax showing filling defect in the right brachiocephalic vein (1) due to thrombus, while the left brachiocephalic vein (2) is patent and shows intense contrast enhancement. 1b CT neck showing patent left internal jugular vein with intense contrast enhancement due to regurgitation (3). Right internal jugular vein is not seen due to thrombus (4). 1c CT thorax showing blocked superior vena cava (5) with thrombus and a rim of contrast enhancement indicating partial block.