A man in his 60s with a history of uremia for 5 years complained of right upper-limb swelling. A stent was implanted in his right brachiocephalic vein 4 months prior. Thoracic venography was performed on a dual-layer spectral computed tomography (CT) scanner. There were some slight low-density filling defects in the stent lumen on conventional CT images suspicious of thrombus formation (Figure, A). Z-effective images indicated thrombosis (Figure, B), which was confirmed by digital subtraction angiography. There was no contrast media visualized in the stent lumen, and obvious collateral veins were opacified due to occlusion of the stent. Dual-layer spectral CT with multiparameter imaging can detect an in-stent thrombus more accurately than conventional CT, and the thrombus can be visualized on Z-effective images.1,2