Abstract Body: Introduction Surpass Evolve (SE) is an updated flow diverter stent. While shown to be effective and safe for treating intracranial aneurysms (IA), blood flow analysis is still limited. In this study we constructed IA models with patient-specific internal carotid artery geometry and conducted hemodynamic flow analysis of treatment with implanted SE. Hypothesis IA neck size affects the flow changes induced by SE. Methods A model of a patient left internal carotid artery was prepared from the UCLA clinical database. Using computer automated design (CAD) software, two variations of a 4 x 4 mm saccular IA were constructed on the ophthalmic segment: a mid-sized neck (~2 mm) and a wide neck (~5 mm). For each case, a SE device measuring 3.25 mm in diameter and 17 mm in length was added to model treatment, and computational flow dynamic (CFD) simulations of pulsatile blood flow were performed. Post-treatment blood flow was quantitatively compared between IA models, specifically intra-aneurysmal flow velocity, pulsatility index (PI), turbulence, vorticity, and wall shear stress (WSS). Results Significantly higher flow pulsatility was observed at the neck of the wide neck IA compared to the mid-sized neck IA (PI = 2.96 and 1.66 respectively). Likewise, peak systolic flow velocities were 32.9% and 118% higher at the body and dome respectively in the wide neck case (Fig. 1). Peak systolic WSS values were observed in both cases at the neck facing the direction of blood flow, in which values exceeded 15 Pa for the wide neck case. In the mid-size neck case, WSS in excess of 3 Pa was not observed beyond the neck region, whereas notable propagation of WSS to the body and dome regions were observed in the wide neck case (Fig. 2). Higher flow vorticity was observed in all regions of the IA for the wide-neck case. Flow within the IA of both mid-size and wide neck cases remained mostly laminar with no observable turbulence relative to that in the parent vessel. Conclusion SE treatment reduced the flow entering the IA at a high curvature area of the ICA. When comparing IA of the same size, increased neck size may reduce the flow reduction effects by 2-fold. We also observed high WSS concentrated at the distal side of the IA neck. As WSS relates to vascular remodeling, following up for distal neck remodeling in post procedure scans could be beneficial to monitor regrowth for SE-treated wide neck IAs.