title: Comparative study of four different spherical embolic particles in an animal model: a morphologic and histologic evaluation.
abstract: OBJECTIVE
  To perform a study in a porcine model comparing four different spherical embolic particles in terms of postembolization patency, deformation, and potential for recanalization, with a focus on a relatively new agent--HepaSphere.
  
  
  METHODS
  Partial embolization of both kidneys was performed in 18 pigs. Nine animals were sacrificed at 48 hours and nine at 4 weeks. In the same animal, the right kidney was embolized with HepaSphere particles ("dry" size, 50-100 microm; presumed final size, 200-300 microm), and the left kidney was alternatively embolized with EmboSphere (100-300 microm), Contour (150-350 microm), or Bead Block (150-350 microm) particles. The authors analyzed the size, deformation, and number of particles in each vessel, their morphologic characteristics, and recanalization.
  
  
  RESULTS
  Particle sizes and deformation (1,096 particles) were as follows: HepaSphere, 225.3 microm +/- 67 and 26% +/- 19.7, respectively; EmboSphere, 132.9 microm +/- 36 and 18.1% +/- 14.2; Bead Block, 108.1 microm +/- 38 and 16.5% +/- 13.9; and Contour, 240.8 microm +/- 135 and 55.5% +/- 33. HepaSphere and Bead Block particles were distally located, and EmboSphere and Contour particles were located more proximally. EmboSphere and Bead Block particles were round, HepaSphere particles were round and/or ovoid, and Contour particles had an amorphous aspect. EmboSphere particles had a higher tendency to aggregate. No recanalization was seen with HepaSphere particles, and variable recanalization was observed with the others.
  
  
  CONCLUSIONS
  Despite similar initial morphologic characteristics, the performance of the agents tested in this study differed in terms of final size, shape, deformation, and luminal recanalization. These differences have potential clinical relevance, and the knowledge of the differing embolic performance may be helpful in choosing agents for specific therapeutic purposes.
authors.affiliation: Department of Radiology, Clínica Universitaria de Navarra, Universidad de Navarra, Avenida de Pio XII, 36, 31008 Pamplona, Spain. jibilbao@unav.es
authors.forename: José I
authors.initials: JI
authors.lastname: Bilbao
authors.forename: Esther
authors.initials: E
authors.lastname: de Luis
authors.forename: José A
authors.initials: JA
authors.lastname: García de Jalón
authors.forename: Alba
authors.initials: A
authors.lastname: de Martino
authors.forename: María D
authors.initials: MD
authors.lastname: Lozano
authors.forename: Antonio Martínez
authors.initials: AM
authors.lastname: de la Cuesta
authors.forename: Bruno
authors.initials: B
authors.lastname: Sangro
mesh_terms: D000180:Acrylic Resins / Q000008:administration & dosage*; D000818:Animals; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D006490:Hemostatics / Q000008:administration & dosage*; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000166:cytology* / Q000187:drug effects*; D023421:Models, Animal; D010316:Particle Size; D013552:Swine
chemical_list: D000180:Acrylic Resins; D006490:Hemostatics