Targeting and Recanalization after Embolization with Calibrated Resorbable Microspheres versus Hand-cut Gelatin Sponge Particles in a Porcine Kidney Model

Abstract Purpose To report on polyethylene glycol hydrogel-based resorbable embolization microspheres (REM) that were synthesized to resorb in Materials and Methods Eight pigs underwent polar renal artery embolization with REM or GSP. Angiograms were obtained before embolization and 10 minutes and 7 days after embolization before pigs were sacrificed to determine the occlusion level, the percentage of occlusion, and the recanalization rate for each product. The distribution of embolic material was assessed in pathology, and infarction rate of the kidneys was measured. Results REM of 300–500 µm occluded more distal vessels than REM of 500–700 µm and 700–900 µm. At day 7, the recanalization rate was complete for the larger REM, whereas it was about 60% for the two smaller sizes. REM were completely degraded, with no residual material or inflammation. GSP occluded more proximal arteries than REM of 700–900 µm, were partly degraded at day 7, and were accompanied by a foreign body reaction in proximal and distal arteries. GSP recanalized at 79%. The infarction rate was higher with the two smaller sizes of REM and with GSP than with the largest REM. Conclusions REM of different sizes targeted different occlusion levels in kidney arteries. GSP provided an extended occlusion level without actual targeting. Regardless of embolic material used, angiographic recanalization of renal arteries depended on the extent of necrosis. REM of 700–900 µm demonstrated the lowest infarction rate and the best recanalization rate.