Comparative in vitro evaluation of microspherical embolisation agents

This study describes the comparative performance of four commercially available microspherical embolisation products: Embosphere, Embogold, Contour SE and Bead Block. A series of in vitro evaluations were designed to assess the mechanical and biological characteristics of these biomaterials. Size distribution analysis revealed sieving techniques used to fractionate the embolics produced similar size distributions. The forces required to compress Embosphere, Embogold and Bead Block were in the range 21-27.5 kPa. Contour SE was significantly more compressible at approximately 5 kPa. However, recoverability of Contour SE required several minutes in contrast to the other products, a phenomenon attributed to its macroporous structure. When time taken to reach and remain in suspension was studied, results showed that the products quickly reached equilibrium with contrast agent. Bead Block was maintained in suspension for twice as long as the other products. Catheter deliverability was assessed and found to be dependent upon both microsphere and catheter, the best combination being Bead Block delivered via the Progreat catheter. Both the blood contacting SEM and plasma coagulation time showed none of the products were pro-thrombic or pro-coagulatory, each producing comparable results. Small differences in physical properties such as compressibility, could play an important role in delivery and effectiveness of vessel blockage. Currently all products are used routinely in clinical practice.