title: IN VITRO QUANTIFICATION OF THE SIZE DISTRIBUTION OF INTRASACCULAR VOIDS LEFT AFTER ENDOVASCULAR COILING OF CEREBRAL ANEURYSMS.
abstract: Endovascular coiling of cerebral aneurysms remains limited by coil compaction and associated recanalization. Recent coil designs which effect higher packing densities may be far from optimal because hemodynamic forces causing compaction are not well understood since detailed data regarding the location and distribution of coil masses are unavailable. We present an in vitro methodology to characterize coil masses deployed within aneurysms by quantifying intra-aneurysmal void spaces.
  
  
  
  Eight identical aneurysms were packed with coils by both balloon- and stent-assist techniques. The samples were embedded, sequentially sectioned and imaged. Empty spaces between the coils were numerically filled with circles (2D) in the planar images and with spheres (3D) in the three-dimensional composite images. The 2D and 3D void size histograms were analyzed for local variations and by fitting theoretical probability distribution functions.
  
  
  
  Balloon-assist packing densities (31±2%) were lower (p=0.04) than the stent-assist group (40±7%). The maximum and average 2D and 3D void sizes were higher (p=0.03 to 0.05) in the balloon-assist group as compared to the stent-assist group. None of the void size histograms were normally distributed; theoretical probability distribution fits suggest that the histograms are most probably exponentially distributed with decay constants of 6-10 mm. Significant (p<=0.001 top=0.03) spatial trends were noted with the void sizes but correlation coefficients were generally low (absoluter<=0.35).
  
  
  
  The methodology we present can provide valuable input data for numerical calculations of hemodynamic forces impinging on intra-aneurysmal coil masses and be used to compare and optimize coil configurations as well as coiling techniques.
authors.affiliation: Department of Neurological Surgery, Stony Brook University Medical Center, Stony Brook, NY.
authors.forename: Chander
authors.initials: C
authors.lastname: Sadasivan
authors.forename: Jeremy
authors.initials: J
authors.lastname: Brownstein
authors.forename: Bhumika
authors.initials: B
authors.lastname: Patel
authors.forename: Ronak
authors.initials: R
authors.lastname: Dholakia
authors.forename: Joseph
authors.initials: J
authors.lastname: Santore
authors.forename: Fawaz
authors.initials: F
authors.lastname: Al-Mufti
authors.forename: Enrique
authors.initials: E
authors.lastname: Puig
authors.forename: Audrey
authors.initials: A
authors.lastname: Rakian
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Fernandez-Prada
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Elhammady
authors.forename: Hamad
authors.initials: H
authors.lastname: Farhat
authors.forename: David J
authors.initials: DJ
authors.lastname: Fiorella
authors.forename: Henry H
authors.initials: HH
authors.lastname: Woo
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Aziz-Sultan
authors.forename: Baruch B
authors.initials: BB
authors.lastname: Lieber
keywords: Balloon; Exponential distribution; Histogram; Porous media; Silicone model; Stent