We reviewed 43 consecutive unruptured bifurcation aneurysms treated with single SAC involving the basilar tip and carotid terminus treated by single SAC with respect to recanalization at latest follow-up (median 12 months). Beside the aneurysm geometry and the treatment-related factors (stent type, initial RG, packing density, and the degree of induced angular remodeling) we analyzed three categories of factors that may affect DB selection including pretreatment bifurcation angle, MB/DB diameter ratio, and lastly the anatomical relation of the neck to the stented DB using a newly introduced parameter; the bifurcation index (BI = bifurcation span across which the stent was deployed into DB/bifurcation span of the other DB). 

During planning for single SAC in basilar tip or carotid terminus aneurysms, DB selection for stent deployment is crucial and it’s important to consider the “Bifurcation Index”. Stent deployment in DB across the long bifurcation span seems to be related to better angiographic outcomes.