title: Absent relationship between the coil-embolization ratio in small aneurysms treated with a single detachable coil and outcomes.
abstract: OBJECTIVE
  Although attenuated coil packing of intracranial aneurysms is an important goal of endovascular embolization, because of their small size, some aneurysms can only be treated with a single embolization coil. We retrospectively analyzed small aneurysms treated with a single Guglielmi detachable coil (GDC) to determine whether the coil-embolization ratio (CER) is predictive of embolization stability.
  
  
  METHODS
  The CER was determined for 25 small (<7-mm diameter) intracranial aneurysms, each treated with a single embolization coil. The largest aneurysm dimension, estimated by comparison to anatomic landmarks, was used for volume calculation based on a spherical model. Coil volumes were according to manufacturer specifications. CER was calculated by the formula (coil volume/aneurysm volume) x 100%. Embolization stability was assessed by angiographic follow-up.
  
  
  RESULTS
  The average CER for all aneurysms was 8.2% (SD, 6.5%; range, 0.6%-21.1%). Twelve percent of the aneurysms had a CER >20%. Follow-up angiographic assessment was conducted at an average of 30.8 months after initial treatment. Eighty-four percent of the aneurysms were obliterated. One large (6 x 10 mm) and 3 small (<1 mm) recurrences were identified. The average CER for unchanged aneurysms was 8.0% (SD, 5.9%) and for the recurrent aneurysms was 8.8% (SD, 8.7%), which was not statistically significant.
  
  
  CONCLUSIONS
  Small aneurysms treated with a single coil achieved satisfactory stability despite having a low average packing attenuation. CER was not predictive of recurrence in small intracranial aneurysms treated with a single detachable coil.
authors.affiliation: Neuroradiology Section, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110-1016, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Goddard
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Moran
authors.forename: DeWitte T
authors.initials: DT
authors.lastname: Cross
authors.forename: Colin P
authors.initials: CP
authors.lastname: Derdeyn
mesh_terms: D000328:Adult; D000368:Aged; D002533:Cerebral Angiography; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies; D016896:Treatment Outcome