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Background and Purpose— The purpose of this study was to identify significant morphological and hemodynamic parameters that discriminate intracranial aneurysm rupture status using 3-dimensional angiography and computational fluid dynamics. Methods— One hundred nineteen intracranial aneurysms (38 ruptured, 81 unruptured) were analyzed from 3-dimensional angiographic images and computational fluid dynamics. Six morphological and 7 hemodynamic parameters were evaluated for significance with respect to rupture. Receiver operating characteristic analysis identified area under the curve (AUC) and optimal thresholds separating ruptured from unruptured aneurysms for each parameter. Significant parameters were examined by multivariate logistic regression analysis in 3 predictive models—morphology only, hemodynamics only, and combined—to identify independent discriminants, and the AUC receiver operating characteristic of the predicted probability of rupture status was compared among these models. Results— Morphological parameters (size ratio, undulation index, ellipticity index, and nonsphericity index) and hemodynamic parameters (average wall shear stress [WSS], maximum intra-aneurysmal WSS, low WSS area, average oscillatory shear index, number of vortices, and relative resident time) achieved statistical significance ( P Conclusion— All 3 models—morphological (based on size ratio), hemodynamic (based on WSS and oscillatory shear index), and combined—discriminate intracranial aneurysm rupture status with high AUC values. Hemodynamics is as important as morphology in discriminating aneurysm rupture status.

We previously used three-dimensional (3D) volumetric analysis to identify a novel intracranial aneurysm (IA) morphological metric, aneurysm-to-parent vessel size ratio (SR), which strongly correlated with aneurysm rupture. However, complex 3D analysis is not easily obtained, and ubiquitous IA risk assessment is traditionally performed with two-dimensional (2D) imaging, typically with size being the sole considered morphometric. Because only easily applicable 2D measurements will be of clinical value, we sought to investigate the correlation of SR determined from 2D angiography with IA rupture status.SR and traditional aspect ratio (AR) and aneurysm size parameters were measured in a retrospective cohort of 38 IA cases (16 ruptured) with 2D rotational angiographic images. These parameters were analysed for correlation with IA rupture status. Student's t-test or Wilcoxon rank-sum test was used for normally or non-normally distributed data respectively. Logistic regression was performed for independently statistically significant parameters to generate an effect size estimate (odds ratio). Area-under-the-curve (AUC) calculated from the receiver-operating-characteristic curve was additionally obtained for each index to describe differentiating capabilities.Only SR achieved statistical significance (p=0.05) in Wilcoxon rank-sum test. Logistic regression generated an SR odds ratio of 3.52 (p=0.04; 95% confidence interval: 1.035-11.938) for every doubling of SR value. The AUC value of SR (0.688) was higher than that of AR (0.642) and size (0.585).SR had the strongest correlation with IA rupture and was demonstrated to be a valuable parameter in 2D, where it can be easily obtained from angiographic images. When eventually evaluated in a prospective data set, SR may prove to be an important tool for aneurysm rupture-risk assessment.

Most clinical studies attempting to stratify the rupture risk of an intracranial aneurysm (IA) have relied on absolute aneurysm size as the primary metric for IA morphology (18, 20, 31, 41). Recent large- scale studies, such as the International Study of Unruptured Intracranial Aneurysms (18, 41), have generated considerable controversy (2, 9, 10, 12, 21, 26) as a result of predicting extremely low rupture rates on the basis of IA size. Numerous studies have disputed the application of size as a predictor of IA rupture risk, pointing out the frequency of subarachnoid hemorrhage from small aneurysms (3, 6, 13, 28). Location-based studies have consistently shown that certain parts of the cerebral vasculature, such as the posterior communicating artery and the anterior communicating artery (AComA), have a higher incidence of ruptured aneurysms when compared with other locations, such as the cavernous segment of the internal carotid artery (ICA) (3, 6, 13, 28, 35, 39, 40). It has also been noted that specific locations on the cerebral vasculature (e.g., AComA) harbor a high percentage of all small ruptured IAs; whereas at other locations (such as the ICA), small, ruptured IAs are substantially less frequent (3, 6, 13, 28). These observations suggest that IA size loses relevance to rupture risk if location is not accounted for. Furthermore, it is likely that the variability of the rupture risk of different locations may be related to the caliber of the originating, or parent, vessel, resulting in higher risks for small- diameter vessels (e.g., AComA or posterior communicating artery ) and lower risks for larger- diameter vessels (e.g., ICA) (3, 6, 13, 28, 35, 39, 40). Evaluation of the contribution of parent vessel geometry to aneurysm rupture risk may help resolve the above-noted conflicts regarding the use of IA size alone as a predictor of rupture risk. In a recent study, we proposed a new parameter, size ratio (SR), defined as maximum aneurysm height/average parent vessel diameter, that incorporates the IA parent vessel geometry into a morphological index (11). That study compared SR with previously identified parameters, such as aneurysm size, aspect ratio, undulation index, ellipticity index, and non-sphericity index, and found SR to have the strongest correlation with IA rupture. It has been hypothesized that the mechanism by which IA morphology relates to IA rupture is via the intra- aneurysmal hemodynamic environment created by a particular geometry (36). Several studies have evaluated the relationship between intra- aneurysmal hemodynamics and IA growth rate and rupture risk (8, 15–17, 19, 23–25, 32, 33, 36). Computational fluid dynamics (CFD) studies of intra- aneurysmal hemodynamics have identified certain flow characteristics to be specific to ruptured aneurysms and, therefore, classified as potentially “dangerous” (8, 32, 36). Regions of markedly low (

Object Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model. Methods Rabbits were subjected to sham surgery (3 animals), unilateral CCA ligation (3 animals), or bilateral CCA ligation (5 animals). Transcranial Doppler ultrasonography and rotational angiography were used to compute BA flow, diameter, wall shear stress (WSS), and a tortuosity index on Days 0, 1, 4, 7, 14, 28, 56, and 84. Basilar artery tissues were stained and analyzed at Day 84. Statistical analysis was performed using orthogonal contrast analysis, repeated measures analysis of variance, or mixed regression analysis of repeated measures. Statistical significance was defined as a probability value < 0.05. Results Basilar artery flow and diameter increased significantly after the procedure in both ligation groups, but only the bilateral CCA ligation group demonstrated significant differences between groups. Wall shear stress significantly increased only in animals in the bilateral CCA ligation group and returned to baseline by Day 28, with 52% of WSS correction occurring by Day 7. Only the bilateral CCA ligation group developed significant BA tortuosity, occurring within 7 days postligation. Unlike the animals in the sham and unilateral CCA ligation groups, the animals in the bilateral CCA ligation group had histological staining results showing a substantial internal elastic lamina fragmentation. Conclusions Increased BA flow results in adaptive BA remodeling until WSS returns to physiological baseline levels. Morphological changes occur rapidly following flow alteration and do not require chronic insult to affect substantial and significant structural transformation. Additionally, it appears that there exists a flow-increase threshold that, when surpassed, results in significant tortuosity.

Augmented Reality (AR) applications hold great promise for mobile users in the near future, but mobile devices cannot yet deliver on this promise. Even the quite substantial processing capabilities of modern mobile devices are not at the level needed for running the latest object recognition, tracking, or rendering methods. Furthermore, the resultant power consumption drains the battery fast. To ensure a great user experience, AR algorithms have to cope with real-world conditions like illumination, jitter, scale, rotation, and noise. The fusion of different optimized AR technologies like 2D or 3D feature tracking, edge detection, gravity awareness, or SLAM should be able to handle these issues to the satisfaction of the end-user but current mobile devices cannot handle these complex algorithms running in real-time and in an “always on–always Augmented mode”. With the “always on–always Augmented” scenario, AR applications need to work on various devices such as smartphones, tablets, PC, etc., and at different form factors such as wearables and head mounted displays. Additionally, technology enablers such as dedicated hardware to accelerate feature tracking and matching that keep the power consumption to an acceptable level, along with easy-to-use software tools and user interfaces designed for non-experts would be the key to provide a low-cost and high volume AR solution. The “always on–always Augmented” scenario also needs considerable cloud support to offload computations and provide a seamless AR experience. To implement these technologies, hardware (HW) architectures have to evolve in parallel to provide efficient resources that can keep power consumption at an acceptable level. In this chapter we discuss the challenges and solutions in embedded processing for a seamless AR user experience in the context of the “always on–always Augmented” use case.

Objective Computational fluid dynamics (CFD) simulations of intracranial aneurysm hemodynamics usually adopt the simplification of the Newtonian blood rheology model. A study was undertaken to examine whether such a model affects the predicted hemodynamics in realistic intracranial aneurysm geometries. Methods Pulsatile CFD simulations were carried out using the Newtonian viscosity model and two non-Newtonian models (Casson and Herschel-Bulkley) in three typical internal carotid artery saccular aneurysms (A, sidewall, oblong-shaped with a daughter sac; B, sidewall, quasi-spherical; C, near-spherical bifurcation). For each aneurysm model the surface distributions of shear rate, blood viscosity and wall shear stress (WSS) predicted by the three rheology models were compared. Results All three rheology models produced similar intra-aneurysmal flow patterns: aneurysm A had a slowly recirculating secondary vortex near the dome whereas aneurysms B and C contained only a large single vortex. All models predicted similar shear rate, blood viscosity and WSS in parent vessels of all aneurysms and in the sacs of B and C. However, large discrepancies in shear rate, viscosity and WSS among predictions by the various rheology models were found in the dome area of A where the flow was relatively stagnant. Here the Newtonian model predicted higher shear rate and WSS values and lower blood viscosity than the two non-Newtonian models. Conclusions The Newtonian fluid assumption can underestimate viscosity and overestimate shear rate and WSS in regions of stasis or slowly recirculating secondary vortices, typically found at the dome in elongated or complex-shaped saccular aneurysms as well as in aneurysms following endovascular treatment. Because low shear rates and low WSS in such flow conditions indicate a high propensity for thrombus formation and rupture, CFD based on the Newtonian assumption may underestimate the propensity of these events.

Objective Flow diversion is a novel concept for intracranial aneurysm treatment. The recently developed Enterprise Vascular Reconstruction Device (Codman & Shurtleff, Inc., Raynham, MA, USA) allows easy delivery and repositioning. Although designed specifically for restraining coils within an aneurysm, this stent has theoretical effects on modifying flow dynamics, which have not been studied. The goal of this study was to quantify the effect of single and multiple self-expanding Enterprise stents alone or in combination with balloon-mounted stents on aneurysm hemodynamics using computational fluid dynamics. Methods The geometry of a wide-necked, saccular, basilar trunk aneurysm was reconstructed from computed tomographic angiography images. Various combinations of one to three stents were “virtually” conformed to fit into the vessel lumen and placed across the aneurysm orifice. Computational fluid dynamics analysis was performed to calculate hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each model. Results The complex aneurysmal flow pattern was suppressed by stenting. Stent placement lowered average flow velocity in the aneurysm; further reduction was achieved by additional stent deployment. Aneurysmal flow turnover time, an indicator of stasis, was increased to 114%–117% for single-stent, 127%–128% for double-stent, and 141% for triple-stent deployment. Furthermore, aneurysmal wall shear stress decreased with increasing number of deployed stents. Conclusion This is the first study analyzing flow modifications associated with placement of Enterprise stents for aneurysm occlusion. Placement of two to three stents significantly reduced intraaneurysmal hemodynamic activities, thereby increasing the likelihood of inducing aneurysm thrombotic occlusion.

Background and Purpose— Hemodynamic insult by bilateral common carotid artery ligation has been shown to induce aneurysmal remodeling at the basilar terminus in a rabbit model. To characterize critical hemodynamics that initiate this remodeling, we applied a novel hemodynamics–histology comapping technique. Methods— Eight rabbits received bilateral common carotid artery ligation to increase basilar artery flow. Three underwent sham operations. Hemodynamic insult at the basilar terminus was assessed by computational fluid dynamics. Bifurcation tissue was harvested on day 5; histology was comapped with initial postligation hemodynamic fields of wall shear stress (WSS) and WSS gradient. Results— All bifurcations showed internal elastic lamina loss in periapical regions exposed to accelerating flow with high WSS and positive WSS gradient. Internal elastic lamina damage happened 100% of the time at locations where WSS was >122 Pa and WSS gradient was >530 Pa/mm. The degree of destructive remodeling accounting for internal elastic lamina loss, medial thinning, and luminal bulging correlated with the magnitude of the hemodynamic insult. Conclusions— Aneurysmal remodeling initiates when local hemodynamic forces exceed specific limits at the rabbit basilar terminus. A combination of high WSS and positive WSS gradient represents dangerous hemodynamics likely to induce aneurysmal remodeling.

Given the considerable risk of treating unruptured intracranial aneurysms (IAs), as well as the known severe morbidity of aneurysm rupture, elucidating those aneurysms that require prophylactic treatment can be a quandary. Traditionally, decision-making to treat an unruptured aneurysm was largely based on the Size of the aneurysm, but recent studies have failed to show significant correlation of Size with IA rupture, and a large number of ruptured aneurysms are small in Size.[1] Consequently, shape-based morphologic metrics have been explored in current investigations, and complex shapes have been correlated with rupture.[1] With the advancement of 3D angiography, and computational fluid dynamics (CFD) technology, patient-specific hemodynamics analysis has become feasible. Intra-aneurysmal hemodynamic factors, including wall shear stress (WSS), impingement regions, and oscillatory shear index (OSI), have been proposed as indicators for IA rupture risk.[2, 3] No study has rigorously examined both morphology-based and hemodynamics-based parameters from a uniform cohort to compare their relative importance. Our aim, therefore, was to identify significant morphologic and hemodynamic parameters that correlate with an aneurysm’s rupture status and examine whether hemodynamic parameters can separate ruptured and unruptured aneurysms better than morphologic parameters.

Hemodynamic insult has long been speculated to be a key factor in intracranial aneurysm (IA) formation,1 but the specifics of hemodynamic insult contributing to this process are not understood. Despite other risk factors, IAs are predominantly found at locations associated with unique hemodynamic stress such as at the apices of arterial bifurcations or outer curves, prominent in high wall shear stress (WSS) and wall shear stress gradients (WSSG).2 Furthermore, it appears that increased flow at these locations is required to trigger the initiation of aneurysmal remodeling.3 We have previously shown that increasing flow in the rabbit basilar artery (BA), secondary to common carotid artery (CCA) ligation, resulted in nascent aneurysm development at the basilar terminus (BT).4 However, it is unclear if certain hemodynamic stress thresholds must be exceeded to trigger aneurysmal remodeling, and whether sustained insult is necessary.Copyright © 2010 by ASME

The effectiveness of Intracranial Aneurysm (IA) size as a predictor for rupture has been debated. The confusing trends observed *unicefwhile stratifying IA rupture risk according to IA size may have arisen from overlooking its morphology and size relative to its parent vessel.Copyright © 2009 by ASME

While the pathogenesis of an intracranial aneurysm (IA) is poorly understood, it has been generally postulated to be related to hemodynamic insult. IAs are predominantly located at apices of arterial bifurcations or outer curves on or near the Circle of Willis, suggesting a potential role of the specific hemodynamics at such locations characterized by high wall shear stress (WSS). Clinically, new IA formation has been observed following local flow increase.Copyright © 2009 by ASME

Hemodynamic forces play critical roles in vascular pathologies such as atherosclerosis, aneurysms, and stenosis. However, detailed relationships between the specific in vivo hemodynamic microenvironment and vascular responses leading to the triggering or exacerbation of pathological remodeling of the vessel remain elusive. We have developed a hemodynamics-biology co-mapping technique that enables in situ correlation between the in vivo blood flow field and vascular changes secondary to hemodynamic insult. The hemodynamics profile is obtained from computational fluid dynamics simulation within the vascular geometry reconstructed from three-dimensional in vivo images, whereas the vascular response is obtained from histology or immunohistochemistry on harvested vascular tissue. The hemodynamics field is virtually sectioned in the histological slicing planes and digitally co-mapped with the histological images, thereby enabling correlation of the specific local vascular responses with the inciting hemodynamic stresses. We demonstrate application of this technique to rabbit basilar terminus subjected to elevated flow. Morphological changes at the basilar terminus 5 days after the flow increase were co-mapped with the initial wall shear stress and wall shear stress gradient distributions, from which localization of destructive remodeling in a specific hemodynamic zone was noticed. This method paves the way for further investigations to determine the connection between in vivo mechanical stimuli and biological responses, such as initiation of aneurysmal remodeling.

Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model.Rabbits were subjected to sham surgery (3 animals), unilateral CCA ligation (3 animals), or bilateral CCA ligation (5 animals). Transcranial Doppler ultrasonography and rotational angiography were used to compute BA flow, diameter, wall shear stress (WSS), and a tortuosity index on Days 0, 1, 4, 7, 14, 28, 56, and 84. Basilar artery tissues were stained and analyzed at Day 84. Statistical analysis was performed using orthogonal contrast analysis, repeated measures analysis of variance, or mixed regression analysis of repeated measures. Statistical significance was defined as a probability value0.05.Basilar artery flow and diameter increased significantly after the procedure in both ligation groups, but only the bilateral CCA ligation group demonstrated significant differences between groups. Wall shear stress significantly increased only in animals in the bilateral CCA ligation group and returned to baseline by Day 28, with 52% of WSS correction occurring by Day 7. Only the bilateral CCA ligation group developed significant BA tortuosity, occurring within 7 days postligation. Unlike the animals in the sham and unilateral CCA ligation groups, the animals in the bilateral CCA ligation group had histological staining results showing a substantial internal elastic lamina fragmentation.Increased BA flow results in adaptive BA remodeling until WSS returns to physiological baseline levels. Morphological changes occur rapidly following flow alteration and do not require chronic insult to affect substantial and significant structural transformation. Additionally, it appears that there exists a flow-increase threshold that, when surpassed, results in significant tortuosity.

Intracranial aneurysms (IA) affect approximately 2 to 5% of the entire population (23, 25). Ruptured IAs typically cause subarachnoid hemorrhage (SAH) and its sequelae, resulting in significant morbidity and mortality. Among patients who have SAH, 50 to 60% will die from the initial hemorrhage and a further 20 to 25% will experience complications (30). However, despite their expected common occurrence, only 1% of all IAs actually rupture (25). Although the morbidity and mortality associated with rupture may suggest that an incidentally detected aneurysm should be treated to forestall the catastrophic event of SAH, the two current methods of treatment (open microsurgical aneurysm clip ligation or endovascular aneurysm coil embolization) are not without some risk of major morbidity and mortality (8, 31). Therefore, an accurate metric (or several metrics) to judge the risk of rupture of an aneurysm is critical to aid in generating the best possible treatment algorithm. Hemodynamics has been shown to play an important role in IA pathophysiology and rupture. Using computational fluid dynamics, Hassan et al. (11) suggested that high wall shear stress (WSS) may be responsible for IA growth and rupture in high-flow aneurysms, whereas the predominant factors causing rupture in low-flow aneurysms are high intra-aneurysmal pressure and flow stasis. Cebral et al. (6) demonstrated that ruptured IAs have unstable flow patterns, smaller impinging jet diameters, and smaller impingement zones. Shojima et al. (24) found that ruptured IAs have a higher average WSS in the aneurysm sac than unruptured IAs. They observed recirculation zones and blood stasis at the apex of ruptured IAs. It is important to realize that IA hemodynamics are strongly dependent on the geometry of the aneurysmal sac and its feeding vessel (11, 13, 26). For a given geometry, Cebral et al. (5) showed that hemodynamics do not vary significantly with physiological variations of flow rate, blood pressure, and waveform. Therefore, suitable parameters characterizing IA geometry can capture the characteristic hemodynamics and potentially predict rupture risk. Several past studies have investigated such parameters. The most ubiquitous parameter is IA size. Although aneurysms exceeding 10 mm in size are considered to be dangerous, several studies have shown that a large percentage of ruptured aneurysms are, in fact, smaller than 10 mm (2, 9, 22, 23, 26, 27, 30). The relationship between IA rupture risk and IA size has yet to be completely elucidated. Aneurysm shape has been studied as well, and certain shape parameters show stronger correlation with rupture than IA size. Aspect ratio (AR), defined as IA height divided by neck diameter, is the most commonly studied shape parameter. Although most findings affirm its importance, they do not converge on a common threshold value (2, 22, 26, 27, 29). Other, more sophisticated, shape parameters such as undulation index (UI), nonsphericity index (NSI), and ellipticity index (EI) have been proposed (22) in an attempt to account for the three-dimensional (3D) nature of IA. Such 3D parameters show promise to be better predictors than lower-dimensional parameters such as size or AR, and they are further examined in the current study. Previous studies have also investigated additional factors that correlate with IA rupture risk, such as familial preponderance, smoking, hypertension, female sex, connective tissue disorder, aneurysm growth rate, and presence of multiple IAs (15-17, 32). However, these studies have not yielded quantifiable metrics that can be readily integrated into the clinical decision-making process. Adding complexity from such diverse variables into our current study would make risk assessment analysis unwieldy. Currently, morphometric evaluation, typically using size alone, is the mainstay of applied aneurysm rupture risk assessment in day-to-day clinical practice. Our aim is to improve such morphological evaluation and better the accuracy of aneurysm rupture risk assessment, something that is fundamental to the current practice of cerebrovascular neurosurgery. A limitation of previous morphology-based rupture risk studies, including those investigating 3D parameters, is that the geometry of the parent artery is typically ignored. Parent artery geometry has a significant influence on the resultant IA hemodynamics and, consequently, the rupture risk. Castro et al. (4) have demonstrated that upstream vessel tortuosity can critically influence intra-aneurysmal hemodynamics. Hassan et al. (11) observed that a greater parent vessel incidence angle shifts the high WSS area toward the aneurysm dome, where rupture-prone blebs often are present, whereas Hoi et al. (13) noted that highly curved parent vessels subject IAs to higher hemodynamic stresses at the inflow zone that might promote growth or rupture. Thus, parent vessel geometry should be accounted for when defining morphological parameters for IA rupture risk prediction. Furthermore, numerous studies have observed a connection between IA rupture risk and vessel location (3, 4, 9, 21, 26, 30). Because vessel location is strongly related to vessel geometry, this finding affirms the importance of vessel geometry for IA rupture risk. Incorporating parent vessel geometry in morphology parameters can, at least to some extent, capture the influence of IA location as well. In the current study, we address the above-mentioned issues and define three new morphology parameters that incorporate IA parent vessel geometry. We analyze a group of 45 IAs (20 ruptured, 25 unruptured) to evaluate new IA rupture parameters, in comparison with five “traditional” parameters that have been described in earlier studies.

Radial fans of the squirrel-cage type are used in various industrial applications. The analysis of such fans via computational fluid mechanics can provide the overall fan performance coefficients, as well as give insights into the detailed flow field. However, a transient simulation of a 3D machine using a sliding grid for the rotating blades still requires prohibitively large computational resources, with CPU run times in the order of months. To avoid such long simulation times, a faster method is developed in this paper. Instead of solving the transient Navier–Stokes equations, they are first averaged over one impeller rotation, and then solved for the mean flow since only this flow is of practical interest. Due to the averaging process, the blades disappear as solid boundaries, but additional equation terms arise, which represent the blade forces on the fluid. An innovative closure model for these terms is developed by calculating forces in 2D blade rows with the same blade geometry as the 3D machine for a range of flow parameters. These forces are then applied in the 3D machine, and the resulting 3D time-averaged flow field and performance coefficients are calculated. The 3D flow field showed several characteristic features of squirrel-cage blowers, such as a cross-flow pattern through the fan at low flow coefficients, and a vortexlike flow pattern at the fan outlet. The 3D fan performance coefficients showed an excellent agreement with experimental data. Since the 3D simulation solves for the mean flow, it can be run as a steady-state problem with a comparatively coarse grid in the blade region, reducing CPU times by a factor of about 10 when compared to a transient simulation with a sliding grid. It is hoped that these savings in computational cost will encourage other researchers and industrial companies to adopt the new method presented here.

There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent™ and Wallstent®) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation.