CHARACTERIZATION OF THE MECHANICAL PROPERTIES OF INDIVIDUAL EMBOLIZATION BEADS

Embolization beads are the most common agents used in interventional radiology to block blood vessels. They are used to reduce or prevent blood supply into vessels feeding a tumor (uterine fibroid, liver, kidney). Controlling their mechanical properties is essential, as the bead injection process and lodging within the vessel strongly depend upon them. We propose a standardized method to characterize the complete viscoelastic behavior of single embolization beads by combining a compression test to measure the bead elasticity with a relaxation test to measure the material viscosity. Those two parameters will be used as a gold standard in developing new embolization beads carrying drugs.

Two commercial agents are tested: polyethylene glycol beads (PG-beads) and Trisacryl Gelatin beads (TG-beads). For validation purposes, measurements are also conducted on alginate beads and compared with.

We show that the tested commercial agents present a linear elastic behavior up to at least 15% of deformation like the alginate beads, and that they have a Young modulus of the order of 5 kPa.
Contrary to the alginate beads that have negligible viscosity (51 /pm 18 kPa.s), the commercial beads exhibit viscoelasticity (viscosity of 1 560 /pm 0.34 kPa.s for the TG-beads and 690 /pm14 kPa.s for the PEG-beads).
The beads present on the market thus have similar elastic properties but present differ relaxation behaviour, which is likely to influence the bead injectability and sustainability of embolization in vivo.