title: Cerebral aneurysm sac growth as the etiology of recurrence after successful coil embolization.
abstract: OBJECTIVE
  Coil compaction is thought to be the main mechanism for recurrence in cerebral aneurysms with previously successful coil embolization. We hypothesize that sac growth may be equally or more important. The objective was to study the relative roles of coil compaction and sac growth as explanations for aneurysm recurrence requiring retreatment in a study population using quantitative 3D image processing methods.
  
  
  METHODS
  From July 2009 to December 2010, 175 aneurysms were coiled at the University of Iowa hospitals and clinics. Eight aneurysms had major recurrence requiring retreatment (4.4-12.1 months between procedures; mean: 7.2 months). The 3D structures of the vessel and coil mass were reconstructed using rotational angiography data scanned before and after both initial coil embolization and retreatment. Changes in the sac and coil mass over time were visualized using model registration techniques and quantified using volume calculations.
  
  
  RESULTS
  All 8 of the coiled aneurysms with major recurrence had significant aneurysm sac growth (15% to 102% increase in volume), independent of change in coil volume. Five aneurysms with major recurrence had sufficient data for assessment of coil compaction. The coil mass volume decreased in 1 aneurysm (12% compaction by volume), did not change significantly in 1 aneurysm (increased by 1%), and significantly increased in 3 aneurysms (8%, 21%, and 25%) between the first treatment and before the second treatment.
  
  
  CONCLUSIONS
  In this study population, aneurysm sac growth, not coil compaction, was the primary mechanism associated with recurrence after initial coil embolization.
authors.affiliation: Department of Neurosurgery, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Hasan
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Nadareyshvili
authors.forename: Anna L
authors.initials: AL
authors.lastname: Hoppe
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Mahaney
authors.forename: David K
authors.initials: DK
authors.lastname: Kung
authors.forename: Madhavan L
authors.initials: ML
authors.lastname: Raghavan
mesh_terms: D000328:Adult; D000368:Aged; D019412:Anatomy, Cross-Sectional; D017542:Aneurysm, Ruptured / Q000473:pathology / Q000601:surgery; D015901:Angiography, Digital Subtraction; D001807:Blood Vessel Prosthesis; D002533:Cerebral Angiography; D004621:Embolization, Therapeutic / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000209:etiology / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D055815:Young Adult