Validity of Woven EndoBridge sizing based on the device-to-aneurysm volume ratio

Background: The Woven EndoBridge (WEB) is a treatment modality available for the treatment of intracranial aneurysms, specifically beneficial in wide-necked bifurcation aneurysms. Conventional sizing methods rely on the manipulation of aneurysm width and height measurements. This results in frequent need for re-sizing after initial WEB insertion attempts. Previous studies have suggested that volume-based sizing may decrease this rate. Methods: We conducted a multicenter retrospective cohort study in three complex vascular centers in the United States from 1 January 2020 to 30 June 2023. All patients who underwent attempted aneurysmal WEB embolization were included. Using three-dimensional angiogram reconstructions, we measured the aneurysm volume. We calculated the WEB volume and measured the WEB-aneurysm volume (WAVe) ratio. The primary outcome was whether a WEB required re-sizing. Results: A total of 133 cases were identified, 114 correctly sized and 19 incorrectly sized. Twelve patients (9.0%) required additional stent placement during WEB insertion. One patient (0.8%) had WEB abandonment. There were no differences in demographic or baseline characteristics between the size/re-sizing cohorts aside from aneurysm location (“other” and basilar locations increased the rate of re-sizing). The median WAVe ratio in our appropriately sized cohort was 0.997 (interquartile range (IQR) 0.826, 1.30) versus 1.14 in our re-sizing cohort (IQR 0.734, 1.51; p = 0.728). Using logistic regression, we identified a WAVe ratio ranging from 0.76 to 1.24 yielding > 80% probability of a successful sizing with 95% confidence. Conclusions: Incorporating volume-based measurements in aneurysm embolization with WEBs may improve rates of re-sizing but has an unclear effect on aneurysm occlusion. A WAVe ratio of 0.76–1.24 provides the greatest probability of appropriate initial WEB sizing.