Creation of radiopaque thrombi for in vivo experiments

PURPOSE: A number of percutaneous thrombectomy devices are undergoing inves tigation for treatment of patients with venous thromboembolism. Use of radi opaque thrombus to monitor thrombus delivery and assess thrombectomy has be en previously reported. The purpose of this project was to quantitatively t est the effect of mixing different ratios of blood and contrast material to facilitate maximum thrombus formation and radiopacity, MATERIALS AND METHODS: The following ratios of blood and contrast material were mixed: 2 mL blood to 8 mL contrast material (ratio = 0.25), 4 mL blood to 6 mt contrast material (ratio = 0.67), 6 mt blood to 4 mt contrast mate rial (ratio = 1.5), and 8 mt blood to 2 mt contrast material (ratio = 4), C ontrast material was added at day 0, 3, or 6. Each sample received one of t wo ionic contrast agents to opacify the clots. At day 14, thrombus mass and opacity were determined. RESULTS: Three combinations of blood and contrast material produced maximum thrombus and radiopacity, These were sodium iothalamate 30% with a ratio o f 4 with contrast material added on day 0 and sodium iothalamate 60% with a ratio of 1.5 with contrast material added on day 3 or 6. CONCLUSIONS: When forming radiopaque thrombi, significant differences can r esult from the ratio of blood to contrast material used. Contrast material type can also affect radiopacity and mass formed. The use of optimal ratios of blood to contrast material should maximize device evaluation with minim al wasting of valuable resources such as test subjects, physician time, and equipment.