Optimizing the Radiopacity of an Injectable Polymer on Fluoroscopy used for Treatment of Type II Endoleak After Endovascular Aneurysm Repair

Purpose: Type II endoleaks (T2EL) are a common complication after endovascular aneurysm repair. AneuFix is a newly designed elastic polymer for T2EL. AneuFix contains tantalum for visualization during fluoroscopy, which is crucial for monitoring the polymer in the side branches. The purpose of this study was to find the lowest concentration tantalum that is sufficient for safe injection in the aneurysmal sac. Methods: AneuFix polymer with tantalum concentrations between 0 and 30% was injected into endoleak phantoms, connected to a pulsatile flow setup and with a realistic background for fluoroscopy. Furthermore, the radiopacity was investigated on fluoroscopic systems from three different vendors, using static phantoms. Results from both the dynamic and static phantoms were qualitatively evaluated by 10 clinical experts. Results: Concentrations of ≥ 20% tantalum were consistently detected within the first 5 mm after entering the side branch, with a corresponding contrast-to-noise ratio of 2.23 ± 0.21. Furthermore, sufficient detectability scores (of at least 3 out of 5) were given to ≥ 15% tantalum. Significant differences were found in detectability scores on different fluoroscopic systems, using the default lowest-radiation-dose scan protocol for each system. Conclusions: This study showed that tantalum concentrations ≥ 20% are consistently detected on fluoroscopy in the specified region. Compared to the original 30%, this would reduce imaging artifacts from high attenuation and scattering on follow-up imaging, while retaining sufficient detectability during injection. However, because of differences in fluoroscopic systems and scan protocols between hospitals, the combination of tantalum concentration and scan protocol should be optimized for each clinical setting.