['Iodinated contrast agent for CT has a short half-life in the vasculature. As the field of interventional procedures expands, a more durable contrast agent would be highly useful. Our study investigated whether gold nanoparticles are feasible as a long-lasting vascular contrast agent for CT.', 'Gold nanoparticles were synthesized by a modified Turkevich method, coated with methoxy-polyethylene glycol-thiol chains, and compared with an iodine-based contrast agent used in mice. Contrast agents were imaged in tubes by CT at 40, 60, and 140 kVp and then were tested in vivo by tail vein injection. Nine mice received gold nanoparticles, two received iodine-based contrast agent, and one received saline. CT of mice was performed at 60 kVp immediately, 6 hours, and 24 hours after injection.', 'In an isolated form in tubes, gold nanoparticles had greater radiographic density than did iodine-based contrast agent at 40 kVp and were comparable at the other CT voltages. In mice, gold nanoparticles provided bright contrast enhancement that enabled clear visualization of the abdominal aorta and renal arteries, which could not be distinguished without contrast agent. This persisted up to 24 hours, which was the last time point assessed. Contrast enhancement of the vasculature by iodine-based contrast agent was present immediately after injection but had disappeared by 6 hours.'] Do gold nanoparticles provide bright long-lasting vascular contrast for CT imaging?