Residual Flow Inside the Woven EndoBridge Device at Follow-Up: Potential Predictors of the Bicêtre Occlusion Scale Score 1 Phenomenon.

BACKGROUND AND PURPOSE The Woven EndoBridge (WEB) device is an established technique for the treatment of intracranial aneurysms. Occasionally, persistent opacification inside the WEB lumen can be observed at follow-up (previously described as Bicetre Occlusion Scale Score 1). We evaluated potential risk factors of this phenomenon, hypothesizing that initial deviation of the WEB device from the aneurysm axis, size of the aneurysmal neck surface, or inappropriate WEB sizing correlates with Bicetre Occlusion Scale Score 1 findings. MATERIALS AND METHODS We systematically reviewed all patients treated with the WEB device between February 2014 and December 2018 in our neurointerventional center. Patients with midterm follow-up DSA available were considered for aneurysm evaluation applying the Bicetre Occlusion Scale Score. WEB angle deviation from the aneurysm axis, neck widths, and WEB sizes were collected. RESULTS We included 65 patients with 67 intracranial aneurysms. Eleven of 67 (16.4%) intracranial aneurysms showed the Bicetre Occlusion Scale Score 1 phenomenon at follow-up. Anterior-posterior projections of WEB axis deviation (angles measured in degrees) were significantly different between the Bicetre Occlusion Scale Score 1 cohort (median ± interquartile range, 17 ± 17) and all other Bicetre Occlusion Scale Scores (median ± interquartile range, 7 ± 11; P = .023), whereas in lateral projections, no significant difference was observed (median ± interquartile range, 10 ± 10 versus 8 ± 9; P = .169). Neck or aneurysm recurrence, but not the Bicetre Occlusion Scale Score 1 phenomenon, occurred significantly more often in patients with inappropriate WEB sizing compared with appropriate WEB sizing (median ± interquartile range, 1 ± 1.3 versus 0 ± 0; P < .001/P = .664). CONCLUSIONS The Bicetre Occlusion Scale Score 1 phenomenon is associated with an initial deviation of the WEB device from the aneurysm axis but does not correlate with aneurysmal neck surface measurements or WEB sizing.