Estimation of trapped thrombus volumes in retrievable inferior vena cava filters: A visual scale

PURPOSE: To establish a visual, objective scale for estimating trapped thrombus volumes in five types of retrievable inferior vena cava filters. MATERIAL AND METHODS: Silicone-based radiopaque polymer volumes of 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, and 4.0 mL were created. Both sphere and cone shapes were used. Polymer volumes were confirmed by means of the water displacement method. The volumes were then positioned to simulate trapped thrombus in five retrievable filters: Recovery and G2 (Bard Peripheral Vascular, Tempe, Ariz), Gunther Tulip and Celect (Cook, Bloomington, Ind), and OptEase (Cordis Endovascular, Warren, NJ). Radiographs were obtained by using conventional parameters. Visual scales of thrombus volume were created for each filter type. RESULTS: Visual scales for each retrievable filter type were created with simulated thrombi in typical trapping positions. CONCLUSION: The authors developed a visual, objective scale for estimating trapped thrombus volume in five types of retrievable IVC filters. This could facilitate standardized reporting of thrombus volumes in studies of optional vena cava filters.