Difference of coil distribution made by finishing coils in large size aneurysm model with radiolucent coils.

We conducted a study to understand the characteristics of the finishing coils to select the appropriate coil for the final stage of embolization. Consequently, experimental embolization was performed on a 10 mm spherical silicone aneurysm filled with radiolucent coils, which simulated a volume embolization ratio of 20%. Nine different coils (i-ED complex ∞ SilkySoft, SilkySoft, ExtraSoft, V-Trak HyperSoft helical, Barricade 10 complex finishing, Optima complex 10 soft, Target 360 Ultra, Galaxy G3 mini, and Axium prime 3D ExtraSoft) were analyzed six times at random. After each coil insertion, indices that include area, Feret diameter, circularity, and centroid center of mass were calculated using biplane x-ray images. Furthermore, these data were analyzed using the spring constant k, which represents the stiffness of the coil. In multiple comparisons, a significant difference was observed in the area analysis. The i-ED complex ∞ SilkySoft was more widespread than Target 360 Ultra (p < 0.05). However, no significant differences were observed in the other indices. The spring constant k value of Target 360 Ultra was 2.5 times larger than that of the i-ED complex ∞ SilkySoft, and it negatively correlated with the area index rather than with the other indices. Notably, it was suggested that the smaller the spring constant k, the wider the distribution of the finishing coils. Although there was little difference between the coils, some coils had characteristics suggesting that good embolization could be expected using appropriate finishing coils.