Transitional hemodynamics in intracranial aneurysms — Comparative velocity investigations with high resolution lattice Boltzmann simulations, normal resolution ANSYS simulations, and MR imaging

Jain, Kartik; Jiang, Jingfeng; Strother, Charles M.; Mardal, Kent‐André

doi:10.1118/1.4964793

Cited by 33 publications

(25 citation statements)

References 61 publications

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“…Several recent numerical studies have reported transitional flow in cerebral aneurysms, 16,18,19 and in this paper, we have shown that there is a difference between the assimilated solution and a corresponding high-resolution simulation that demonstrated transient to turbulent behaviour. There are two main reasons that transitional or turbulent flow is not captured by our assimilation procedure: (1) The resolution in space and time is too coarse and (2) transient and/or turbulent flow would likely require the simulation of many cardiac cycles, possibly combined with periodic boundary conditions.…”

Section: Conclusion Discussion and Future Workmentioning

confidence: 53%

“…In contrast, the temporal resolution in CFD simulations is typically on the order of thousands of timesteps per second. As a result, there is often a notable discrepancy between CFD simulations and PC‐MRI measurements . To what extent these discrepancies arise from modelling errors, the spatio‐temporal averaging, or measurement errors is at present difficult to assess in particular because of the methodological challenge of incorporating the available data and control parameters in a simulation framework.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Variational data assimilation for transient blood flow simulations: Cerebral aneurysms as an illustrative example

Funke

Nordaas

Evju

et al. 2018

Numer Methods Biomed Eng

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Several cardiovascular diseases are caused from localised abnormal blood flow such as in the case of stenosis or aneurysms. Prevailing theories propose that the development is caused by abnormal wall shear stress in focused areas. Computational fluid mechanics have arisen as a promising tool for a more precise and quantitative analysis, in particular because the anatomy is often readily available even by standard imaging techniques such as magnetic resonance and computed tomography angiography. However, computational fluid mechanics rely on accurate initial and boundary conditions, which are difficult to obtain. In this paper, we address the problem of recovering high-resolution information from noisy and low-resolution physical measurements of blood flow (for example, from phase-contrast magnetic resonance imaging [PC-MRI]) using variational data assimilation based on a transient Navier-Stokes model. Numerical experiments are performed in both 3D (2D space and time) and 4D (3D space and time) and with pulsatile flow relevant for physiological flow in cerebral aneurysms. The results demonstrate that, with suitable regularisation, the model accurately reconstructs flow, even in the presence of significant noise.

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Section: Conclusion Discussion and Future Workmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Variational data assimilation for transient blood flow simulations: Cerebral aneurysms as an illustrative example

Funke

Nordaas

Evju

et al. 2018

Numer Methods Biomed Eng

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show abstract

“…As a main numerical parameter driving the flow split between daughter branches, the outflow boundary condition often relies on a default zero pressure condition 17 which constitutes a potential source of errors. 5,18 A proper way to bypass this restriction consists in applying an outflow condition from measurements, although these latter are certainly not free of errors.…”

Section: Van Ooij Et In-vitro/vivo Intracranial Velocitymentioning

confidence: 99%

Reconciling PC‐MRI and CFD: An in‐vitro study

et al. 2019

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Several well-resolved 4D Flow MRI acquisitions of an idealized rigid flow phantom featuring an aneurysm, a curved channel as well as a bifurcation were performed under pulsatile regime. The resulting hemodynamics were processed to remove MRI artifacts. Subsequently, they were compared with CFD predictions computed on the same flow domain, using an in-house high-order low dissipative flow solver. Results show that reaching a good agreement is not straightforward but requires proper treatments of both techniques. Several sources of discrepancies are highlighted and their impact on the final correlation evaluated. While a very poor correlation (r 2 = 0.63) is found in the entire domain between raw MRI and CFD data, correlation as high as r 2 = 0.97 is found when artifacts are removed by post-processing the MR data and down sampling the CFD results to match the MRI spatial and temporal resolutions.This work demonstrates that, in a well-controlled environment, both PC-MRI and CFD might bring reliable and correlated flow quantities when a proper methodology to reduce the errors is followed. KEYWORDS cardiovascular blood flows, computational fluid dynamics, large eddy simulation, phase contrast magnetic resonance imaging, validation work flow

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“…Further details on these aspects can be referred to in the works of Hasert et al 36,37 A specific verification of Musubi for transitional flows in physiologically realistic geometries can be found in references. 17,20,21…”

Section: Computational Detailsmentioning

confidence: 99%

Direct numerical simulation of transitional hydrodynamics of the cerebrospinal fluid in Chiari I malformation: The role of cranio‐vertebral junction

Jain

Ringstad

Eide

et al. 2017

Numer Methods Biomed Eng

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Obstruction to the cerebrospinal fluid (CSF) outflow caused by the herniation of cerebellar tonsils as a result of Chiari malformation type I leads to altered CSF hydrodynamics. This contribution explores the minutest characteristics of the CSF hydrodynamics in cervical subarachnoid space (SAS) of a healthy subject and 2 Chiari patients by performing highly resolved direct numerical simulation. The lattice Boltzmann method is used for the simulations because of its scalability on modern supercomputers that allow us to simulate up to approximately 10 cells while resolving the Kolmogorov microscales. The results depict that whereas the complex CSF flow remains largely laminar in the SAS of a healthy subject, constriction of the cranio-vertebral junction in Chiari I patients causes manifold fluctuations in the hydrodynamics of the CSF. These fluctuations resemble a flow that is in a transitional regime rather than laminar or fully developed turbulence. The fluctuations confine near the cranio-vertebral junction and are triggered due to the tonsillar herniation, which perturbs the flow as a result of altered anatomy of the SAS.

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Transitional hemodynamics in intracranial aneurysms — Comparative velocity investigations with high resolution lattice Boltzmann simulations, normal resolution ANSYS simulations, and MR imaging

Cited by 33 publications

References 61 publications

Variational data assimilation for transient blood flow simulations: Cerebral aneurysms as an illustrative example

Variational data assimilation for transient blood flow simulations: Cerebral aneurysms as an illustrative example

Reconciling PC‐MRI and CFD: An in‐vitro study

Direct numerical simulation of transitional hydrodynamics of the cerebrospinal fluid in Chiari I malformation: The role of cranio‐vertebral junction

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