Finite Element Study of Conformity of Flow Diverter With Intracranial Aneurysmal Vasculatures

Endovascular stents in the last decade have been extensively used in intracranial aneurysm (IA) management. Stenting procedure is normally performed with the placement of spring coils inside the aneurysm, where stent will serve as a mechanical scaffold to help anchor the packed coils. Although coiling holds relatively lower morbidity and mortality rate than traditional treatment, its applications to wide-necked IAs, IAs with large fusiform shapes, and thin-walled IAs are still problematic due to the difficulty of securing the coils in the first two scenarios and the vascular susceptibility to coil damage in the last situation. Recent flow diverter concept however offers a potential alternative to address these challenging cases with only stent (flow diverter) being implanted. A flow diverter stent usually has relatively high metal surface coverage rate (∼80%) so that it can significantly divert blood flow from going inside the aneurysm, causing the decreased flow in IA and subsequently the thrombogenic cascade in favor of occluding the lesion. Meanwhile, a new flow conduit across IA orifice is expected to form based on endothelial cell re-pavement on the inner surface of the stent. It is thus of academic and clinical importance to further examine the mechanisms involved with flow diverter to better understand the procedure and improve the treatment outcome. Since the straightening of vessel by stent and incomplete apposition between stent filaments and arterial wall could both induce complications, current study applies a developed finite element method (FEM) workflow to evaluate the conformity of a CoCr alloy flow diverter (Pipeline™ Embolization Device as PED by ev3, MN, USA) to patient specific IA geometries.