title: Evaluation of particulate embolic materials with MR imaging, scanning electron microscopy, and phase-contrast microscopy.
abstract: OBJECTIVE
  To analyze the properties and embolic effect of microfibrillar collagen (MFC), Gelfoam powder, and polyvinyl alcohol (PVA) materials that are used in embolization procedures in the head and neck.
  
  
  METHODS
  The shape and surface of these embolic agents were examined with scanning electron microscopy and phase-contrast microscopy. The mean number of areas of T2-weighted high signal intensity was measured on MR images in a rat embolization model to estimate the embolic effect.
  
  
  RESULTS
  By scanning electron microscopy and phase-contrast microscopy, MFC appears fibriform and has various sizes and an irregular surface. Gelfoam is of uniform size and has a smooth surface. PVA materials are granulated and have a rough surface. MFC is somewhat suspendable and its shape changes moderately after suspension. Gelfoam is very suspendable and its shape changes rapidly. PVA showed only mild swelling. The embolic effect of MFC was the lowest of the materials examined. Large PVA particles (250 to 500 microns) showed a lesser embolic effect than Gelfoam or small PVA particles (50 to 150 microns) or medium-sized PVA particles (150 to 250 microns). No significant differences were observed among the embolic effects of Gelfoam, small PVA particles (50 to 150 microns), and medium PVA particles (150 to 250 microns).
  
  
  CONCLUSIONS
  MFC and large PVA particles (250 to 500 microns) should be used for embolization of vascular anatomy involving potentially dangerous anastomoses. Gelfoam, PVA particles of 150- to 250-micron diameter, and PVA particles of 50- to 150-micron diameter are adequate for embolization involving homogeneous and peripheral anatomy.
authors.affiliation: Department of Neurosurgery, Nagoya (Japan) University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakabayashi
authors.forename: M
authors.initials: M
authors.lastname: Negoro
authors.forename: T
authors.initials: T
authors.lastname: Handa
authors.forename: H
authors.initials: H
authors.lastname: Keino
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Sugita
mesh_terms: D000818:Animals; D002339:Carotid Arteries / Q000473:pathology; D003094:Collagen / Q000648:ultrastructure*; D004621:Embolization, Therapeutic; D005781:Gelatin Sponge, Absorbable; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D008858:Microscopy, Phase-Contrast / Q000379:methods*; D010316:Particle Size; D011142:Polyvinyl Alcohol; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties
chemical_list: D011142:Polyvinyl Alcohol; D003094:Collagen