title: Relationship between Two Types of Coil Packing Densities Relative to Aneurysm Size.
abstract: OBJECTIVE
  Coil packing density (PD) can be calculated via a formula (PDF ) or software (PDS ). Two types of PD can be different from each other for same aneurysm. This study aimed to evaluate the interobserver agreement and relationships between the 2 types of PD relative to aneurysm size.
  
  
  METHODS
  Consecutive 420 saccular aneurysms were treated with coiling. PD (PDF , [coil volume]/[volume calculated by formula] and PDS, [coil volume]/[volume measured by software]) was calculated and prospectively recorded. Interobserver agreement was evaluated between PDF and PDS . Additionally, the relationships between PDF and PDS relative to aneurysm size were subsequently analyzed.
  
  
  RESULTS
  Interobserver agreement for PDF and PDS was excellent (Intraclass correlation coefficient, PDF ; 0.967 and PDS ; 0.998). The ratio of PDF and PDS was greater for smaller aneurysms and converged toward 1.0 as the maximum dimension (DM ) of aneurysm increased. Compared with PDS , PDF was overestimated by a mean of 28% for DM < 5 mm, by 17% for 5 mm ≤ DM < 10 mm, and by 9% for DM ≥ 10 mm (P < 0.01).
  
  
  CONCLUSIONS
  Interobserver agreement for PDF and PDS was excellent. However, PDF was overestimated in smaller aneurysms and converged to PDS as aneurysm size increased.
authors.affiliation: Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Keun Young
authors.initials: KY
authors.lastname: Park
authors.forename: Byung Moon
authors.initials: BM
authors.lastname: Kim
authors.forename: Eun Hyun
authors.initials: EH
authors.lastname: Ihm
authors.forename: Jang Hyun
authors.initials: JH
authors.lastname: Baek
authors.forename: Dong Joon
authors.initials: DJ
authors.lastname: Kim
authors.forename: Dong Ik
authors.initials: DI
authors.lastname: Kim
authors.forename: Seung Kon
authors.initials: SK
authors.lastname: Huh
authors.forename: Jae Whan
authors.initials: JW
authors.lastname: Lee
mesh_terms: D002533:Cerebral Angiography / Q000379:methods*; D004621:Embolization, Therapeutic / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000628:therapy*; D015588:Observer Variation; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Aneurysm; coiling; packing density