Quantitative Hemodynamic Analysis of Brain Aneurysms at Different Locations

Chien, Aichi; Castro, Marcelo; Tateshima, Satoshi; Sayre, James W.; Cebral, Juan R.; Viñuela, Fernando

doi:10.3174/ajnr.a1600

Cited by 55 publications

(35 citation statements)

References 33 publications

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“…First, we investigated middle cerebral artery aneurysms. Studying aneurysms at similar anatomical locations allows us to focus on the hemodynamic features, but the intra-aneurysmal hemodynamics in this location can differ from those in other locations [31,32]. Second, the number of cases in this study is relatively small.…”

Section: Discussionmentioning

confidence: 99%

Local Hemodynamics at the Rupture Point of Cerebral Aneurysms Determined by Computational Fluid Dynamics Analysis

Omodaka¹,

Sugiyama²,

Inoue

et al. 2012

Cerebrovasc Dis

105

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Background: Cerebral aneurysms carry a high risk of rupture and so present a major threat to the patient’s life. Accurate criteria for predicting aneurysm rupture are important for therapeutic decision-making, and some clinical and morphological factors may help to predict the risk for rupture of unruptured aneurysms, such as sex, size and location. Hemodynamic forces are considered to be key in the natural history of cerebral aneurysms, but the effect on aneurysm rupture is uncertain, and whether low or high wall shear stress (WSS) is the most critical in promoting rupture remains extremely controversial. This study investigated the local hemodynamic features at the aneurysm rupture point. Methods: Computational models of 6 ruptured middle cerebral artery aneurysms with intraoperative confirmation of rupture point were constructed from 3-dimensional rotational angiography images. Computational fluid dynamics (CFD) simulations were performed under pulsatile flows using patient-specific inlet flow conditions. Time-averaged WSS (TAWSS) and oscillatory shear index (OSI) were calculated, and compared at the rupture point and at the aneurysm wall without the rupture point. We performed an additional CFD simulation of a bleb-removed model for a peculiar case in which bleb formation could be confirmed by magnetic resonance angiography. Results: All rupture points were located at the body or dome of the aneurysm. The TAWSS at the rupture point was significantly lower than that at the aneurysm wall without the rupture point (1.10 vs. 4.96 Pa, p = 0.031). The OSI at the rupture point tended to be higher than at the aneurysm wall without the rupture point, although the difference was not significant (0.0148 vs. 0.0059, p = 0.156). In a bleb-removed simulation, the TAWSS at the bleb-removed area was 6.31 Pa, which was relatively higher than at the aneurysm wall (1.94 Pa). Conclusion: The hemodynamics of 6 ruptured cerebral aneurysms of the middle cerebral artery were examined using retrospective CFD analysis. We could confirm the rupture points in all cases. With those findings, local hemodynamics of ruptured aneurysms were quanti-tatively investigated. The rupture point is located in a low WSS region of the aneurysm wall. Bleb-removed simulation showed increased WSS of the bleb-removed area, associated with the flow impaction area. Although the number of subjects in this study was relatively small, our findings suggest that the location of the rupture point is related to a low WSS at the aneurysm wall. Further investigations will elucidate the detailed hemodynamic effects on aneurysm rupture.

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Section: Discussionmentioning

confidence: 99%

Local Hemodynamics at the Rupture Point of Cerebral Aneurysms Determined by Computational Fluid Dynamics Analysis

Omodaka¹,

Sugiyama²,

Inoue

et al. 2012

Cerebrovasc Dis

105

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“…Because aneurysm hemodynamic properties are affected by location, posterior communicating artery aneurysms (which had the most cases with before and after rupture images) were selected. 18 Six ruptured posterior communicating artery aneurysms had clinical images documenting aneurysms before and after rupture. The aneurysms were not treated because of advanced patient age.…”

Section: Methodsmentioning

confidence: 99%

“…For all cases, a standard ICA flow profile acquired from a healthy subject with phase-contrast MR imaging was applied. 5,6,18,22 The qualitative hemodynamic risk factors analyzed included aneurysm inflow jet size, flow impingement size, and aneurysmal flow pattern, as proposed by Cebral et al 5 Quantitative hemodynamic risk factors, including normalized wall shear stress (WSS), maximum aneurysm wall shear stress, and pulsatility index were analyzed. 8,15,22 On the basis of the indices proposed by Xiang et al, 15 normalized aneurysm wall shear stress was obtained by averaging wall shear stress over a cardiac cycle (equation 6), and maximum aneurysm wall shear stress was defined as maximum intra-aneurysmal WSS normalized by the average parent artery WSS (equation 7).…”

Section: Methodsmentioning

confidence: 99%

Morphologic and Hemodynamic Risk Factors in Ruptured Aneurysms Imaged before and after Rupture

Chien¹,

Sayre

2014

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE:Due to limited information about aneurysm natural history, choosing the appropriate management strategy for an unruptured aneurysm is challenging. By comparing unruptured and ruptured cases, studies have identified a variety of aneurysm morphologic and hemodynamic properties as risk factors for rupture. In this study, we investigated changes in 4 ruptured aneurysms before and after rupture and tested whether previously published risk factors identified a risk before rupture.

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“…As for the specification of inlet flow magnitude, different authors adopted different assumptions across different cases, namely the same flow velocity, 12,27,33,34 the same flow rate, 4,13,20,28,30,31,35 or the same WSS. 5,[22][23][24][25][26]43,61 The specified values were either taken from the literature or measured from one subject. Because the inlet boundary condition specified in this way is not patient-specific, absolute levels of physical quantities, such as WSS, calculated from CFD are not accurate.…”

Section: Cfd Studies Of High and Low Wss In Aneurysm Rupturementioning

confidence: 99%

CFD: Computational Fluid Dynamics or Confounding Factor Dissemination? The Role of Hemodynamics in Intracranial Aneurysm Rupture Risk Assessment

Xiang

Tutino

Snyder

et al. 2013

AJNR Am J Neuroradiol

169

115

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SUMMARY:Image-based computational fluid dynamics holds a prominent position in the evaluation of intracranial aneurysms, especially as a promising tool to stratify rupture risk. Current computational fluid dynamics findings correlating both high and low wall shear stress with intracranial aneurysm growth and rupture puzzle researchers and clinicians alike. These conflicting findings may stem from inconsistent parameter definitions, small datasets, and intrinsic complexities in intracranial aneurysm growth and rupture. In Part 1 of this 2-part review, we proposed a unifying hypothesis: both high and low wall shear stress drive intracranial aneurysm growth and rupture through mural cell-mediated and inflammatory cell-mediated destructive remodeling pathways, respectively. In the present report, Part 2, we delineate different wall shear stress parameter definitions and survey recent computational fluid dynamics studies, in light of this mechanistic heterogeneity. In the future, we expect that larger datasets, better analyses, and increased understanding of hemodynamicbiologic mechanisms will lead to more accurate predictive models for intracranial aneurysm risk assessment from computational fluid dynamics. ABBREVIATIONS:CFD ϭ computational fluid dynamics; IA ϭ intracranial aneurysm; LSA ϭ low shear-stress area; MWSS ϭ maximum wall shear stress; OSI ϭ

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Quantitative Hemodynamic Analysis of Brain Aneurysms at Different Locations

Cited by 55 publications

References 33 publications

Local Hemodynamics at the Rupture Point of Cerebral Aneurysms Determined by Computational Fluid Dynamics Analysis

Local Hemodynamics at the Rupture Point of Cerebral Aneurysms Determined by Computational Fluid Dynamics Analysis

Morphologic and Hemodynamic Risk Factors in Ruptured Aneurysms Imaged before and after Rupture

CFD: Computational Fluid Dynamics or Confounding Factor Dissemination? The Role of Hemodynamics in Intracranial Aneurysm Rupture Risk Assessment

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