title: Collagen-coated acrylic microspheres for embolotherapy: in vivo and in vitro characteristics.
abstract: OBJECTIVE
  To evaluate the in vivo and in vitro properties of collagen-coated acrylic microspheres and to compare them with polyvinyl alcohol (PVA) particles.
  
  
  METHODS
  Samples of 100- to 300-microns, 300- to 500-microns, 500- to 700-microns, and 700- to 900-microns collagen-coated acrylic microspheres and 200- to 300-microns PVA particles were suspended in solutions of 50% saline and 50% contrast material. The samples were evaluated for quantitative and qualitative microscopic characteristics (shape, size, deformability); injectability via standardized microcatheters; degree of particulate penetration in the pig rete mirabile; and reaction of tissue to the particles in 48-hour- and 4-week-old specimens.
  
  
  RESULTS
  The acrylic microspheres were spherical and deformable. The sample of 100- to 300-microns microspheres (n = 202) had a mean diameter of 210 microns (standard deviation, 43 microns). Hub accumulation, particle aggregation, and catheter occlusion were not observed with the microspheres (all sizes) but were noted with the PVA particles. The 200- to 300-microns PVA particles formed aggregates in the proximal rete. The 100- to 300-microns microspheres were found throughout the rete and beyond. Chronic transmural and perivascular inflammation was observed with the microspheres and the PVA particles.
  
  
  CONCLUSIONS
  Particle aggregation and catheter occlusion do not complicate the transcatheter delivery of collagen-coated acrylic microspheres as they do with PVA particles. For a given particle and vessel size, acrylic microspheres penetrate to a much greater extent than the PVA particles. Tissue reaction to acrylic microspheres and PVA particles is similar.
authors.affiliation: Department of Radiology, University of Wisconsin Hospitals and Clinics, Madison, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: Derdeyn
authors.forename: V B
authors.initials: VB
authors.lastname: Graves
authors.forename: M S
authors.initials: MS
authors.lastname: Salamat
authors.forename: A
authors.initials: A
authors.lastname: Rappe
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D001792:Blood Platelets / Q000473:pathology; D002342:Carotid Artery, External / Q000000981:diagnostic imaging / Q000473:pathology; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000473:pathology; D002404:Catheterization / Q000295:instrumentation; D003094:Collagen / Q000737:chemistry; D003287:Contrast Media; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D004867:Equipment Design; D005337:Fibrin; D015726:Giant Cells / Q000473:pathology; D007249:Inflammation; D008845:Microinjections / Q000295:instrumentation; D008853:Microscopy; D008863:Microspheres; D009504:Neutrophils / Q000473:pathology; D010316:Particle Size; D011142:Polyvinyl Alcohol / Q000737:chemistry; D011859:Radiography; D012965:Sodium Chloride; D013499:Surface Properties; D013552:Swine; D013927:Thrombosis / Q000473:pathology; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; D003287:Contrast Media; D012965:Sodium Chloride; D005337:Fibrin; D011142:Polyvinyl Alcohol; D003094:Collagen