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Original research
Interobserver variability in the assessment of aneurysm occlusion with the WEB aneurysm embolization system
  1. David Fiorella1,
  2. Adam Arthur2,
  3. James Byrne3,
  4. Laurent Pierot4,
  5. Andy Molyneux3,
  6. Gary Duckwiler5,
  7. Thomas McCarthy6,
  8. Charles Strother7
  1. 1Stony Brook University Medical Center, Stony Brook, New York, USA
  2. 2Semmes-Murphy Clinic, Memphis, Tennessee, USA
  3. 3Oxford University Neurovascular and Neuroradiology Research Unit, Oxford, UK
  4. 4Hôpital Maison-Blanche, Université Reims-Champagne-Ardenne, Reims, France
  5. 5Department of Interventional Neuroradiology, UCLA, Los Angeles, California, USA
  6. 6Sequent Medical, Inc, Aliso Viejo, California, USA
  7. 7University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
  1. Correspondence to Dr D Fiorella, Department of Neurological Surgery, Stony Brook University Medical Center, Cerebrovascular Center, Health Sciences Center T-12 080, Stony Brook, NY 11794-8122, USA; david.fiorella{at}


Objective The WEB (WEB aneurysm embolization system, Sequent Medical, Aliso Viejo, California, USA) is a self-expanding, nitinol, mesh device designed to achieve aneurysm occlusion after endosaccular deployment. The WEB Occlusion Scale (WOS) is a standardized angiographic assessment scale for reporting aneurysm occlusion achieved with intrasaccular mesh implants. This study was performed to assess the interobserver variability of the WOS.

Methods Seven experienced neurovascular specialists were trained to apply the WOS. These physicians independently reviewed angiographic image sets from 30 patients treated with the WEB under blinded conditions. No additional clinical information was provided. Raters graded each image according to the WOS (complete occlusion, residual neck or residual aneurysm). Final statistics were calculated using the dichotomous outcomes of complete occlusion or incomplete occlusion. The interobserver agreement was measured by the generalized κ statistic.

Results In this series of 30 test case aneurysms, observers rated 12–17 as completely occluded, 3–9 as nearly completely occluded, and 9–11 as demonstrating residual aneurysm filling. Agreement was perfect across all seven observers for the presence or absence of complete occlusion in 22 of 30 cases. Overall, interobserver agreement was substantial (κ statistic 0.779 with a 95% CI of 0.700 to 0.857).

Conclusions The WOS allows a consistent means of reporting angiographic occlusion for aneurysms treated with the WEB device.

  • Aneurysm
  • Flow Diverter
  • Angiography

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