COLLAGEN-COATED ACRYLIC MICROSPHERES FOR EMBOLOTHERAPY - IN-VIVO AND IN-VITRO CHARACTERISTICS

PURPOSE: To evaluate the in vivo and in vitro properties of collagen-c oated acrylic microspheres and to compare them with polyvinyl alcohol (PVA) particles. METHODS: Samples of 100- to 300-mu m, 300- to 500-mu m, 500- to 700-mu m, and 700- to 900-mu m collagen-coated acrylic micr ospheres and 200- to 300-mu m PVA particles were suspended in solution s of 50% saline and 50% contrast material. The samples were evaluated for quantitative and qualitative microscopic characteristics (shape, s ize, deformability); injectability via standardized microcatheters; de gree of particulate penetration in the pig rete mirabile; and reaction of tissue to the particles in 48-hour- and 4-week-old specimens. RESU LTS: The acrylic microspheres were spherical and deformable. The sampl e of 100- to 300-mu microspheres (n = 202) had a mean diameter of 210 mu m (standard deviation, 43 mu m). Hub accumulation, particle aggrega tion, and catheter occlusion were not observed with the microspheres ( all sizes) but were noted with the PVA particles. The 200- to 300-mu m PVA particles formed aggregates in the proximal rete. The 100- to 300 -mu m microspheres were found throughout the rete and beyond. Chronic transmural and perivascular inflammation was observed with the microsp heres and the PVA particles. CONCLUSIONS: Particle aggregation and cat heter occlusion do not complicate the transcatheter delivery of collag en-coated acrylic microspheres as they do with PVA particles. For a gi ven particle and vessel size, acrylic microspheres penetrate to a much greater extent than the PVA particles. Tissue reaction to acrylic mic rospheres and PVA particles is similar.