Intracranial Aneurysms (IA) are life-threatening vascular pathologies associated with high morbidity and mortality. Hemodynamic parameters are widely investigated as predictors of IA growth, rupture and treatment outcome. While most studies rely on CFD or simplified in vitro models, the complexity of the vascular structure geometric complexity has been shown to significantly affect the aneurysm hemodynamics significantly [1]. In this study, we experimentally experimentally investigated the impact of branching vessel and outlet configurations on the IA flow using SLA in 3D-printed patient-specific IA models. The vasculature of Three three patients patient-specific intracranial vascular geometries were acquired using 3D rotational angiography (3D RA). All cases featured with wide-neck saccular IA (with a mean dome-to-neck ratio ≈ 1.2) was imaged using 3D rotational angiography (3D RA). For comparative hemodynamic analysis, . Each patient dataset was simplified into two models geometric variants with different numbers of branching outlets were constructed for each patient to enable comparative hemodynamic analysis (Patient 1: (3/5 outlets), Patient 2: (4/5 outlets), Patient 3: (3/5 outlets)). The maximum number of retained branching outlets was constrained by the printer volume (Formlabs 3B+ build volume (145 × 145 × 185 mm3) and resin consumption (ca. , with an average usage of approximately 50 mL per print and approximately 30 hrs per print on average). The vascular models were created by segmenting the angiographic data 3D RA data and adding uniform 3 mm uniform vessel walls with a thickness of 3 mm [2], printed by stereolithography (. The models were fabricated by SLA (Formlabs Form 3B+, Clear Resin V4, Layer height h = 0.100mm) and embedded in agarose gel. In vitro flow experiments were performed to assess aneurysm hemodynamics, currently using a single patient-specific model (Patient 1, 3 outlets). The patient model was connected to a pulsatile pump (PD 1100, BDC Industries) and perfused with a 40/60 vol% glycerol–water solution doped with a Gd-based contrast agent, 0.33 ml Gadovist (which and how much? Add.) at a volumetric flow rate of 250" ml/min" . MRI was performed on a 3.0 T Philips Ingenia system using a 64-channel head/neck receive coil (Ingenia, Philips Healthcare). Velocity maps were measurements were acquired using 2D phase-contrast (PC) and 4D flow MRI with spatial resolution of 0.5 and 0.7 mm³3, isotropic respectively., on a 3T MRI system