Modeling Flow in Cerebral Aneurysm After Coils Embolization Treatment: A Realistic Patient-Specific Porous Model Approach

Bhathal, Julia Romero; Chassagne, Fanette; Marsh, Laurel; Levitt, Michael R.; Geindreau, Christian; Aliseda, Alberto

doi:10.1007/s13239-022-00639-x

Cited by 3 publications

(3 citation statements)

References 25 publications

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“…We then generated an accuracy score for each binary matrix (percentage of binary voxels that match between the two geometries), shown in Table 1 . As local porosity has been demonstrated to dictate coiled aneurysm hemodynamics (26) we generated porosity maps for each of the coil geometries by calculating the porosity in every 5×5×5 cube in the binary voxelized grid such that the face of each cube is approximately the size of the coil cross section. We then calculated the Pearson’s Correlation Coefficient and average error for each of the porosity maps, also shown in Table 1 .…”

Section: Resultsmentioning

confidence: 99%

“…We recognize that when dealing with large datasets or when computational resources are limited, conducting FEM simulations may be infeasible due to the computational cost associated with resolving the coil geometries. In this case we recommend generating localized porosity maps based on our previous work, (26) as this better approximates the porosity variation of the coil mass.…”

Section: Discussionmentioning

confidence: 99%

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Improving Computational Fluid Dynamics Simulations of Coiled Aneurysms Using Finite Element Modeling

Fillingham

Bhathal

Marsh

et al. 2023

Preprint

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Cerebral aneurysms are a serious clinical challenge, with ∼half resulting in death or disability. Treatment via endovascular coiling significantly reduces the chances of rupture, but the technique has failure rates between 25-40%. This presents a pressing need to develop a method for determining optimal coil deployment strategies. Quantification of aneurysm hemodynamics through computational fluid dynamics (CFD) has the potential to significantly improve the understanding of the mechanics of aneurysm coiling and improve treatment outcomes, but accurately representing the coil mass in CFD simulations remains a challenge. We have used the Finite Element Method (FEM) for simulating patient-specific coil deployment based on mechanical properties and coil geometries provided by the device manufacturer for n=4 ICA aneurysms for which 3D printedin vitromodels were also generated, coiled, and scanned using ultra-high resolution synchrotron micro-CT. The physical and virtual coil geometries were voxelized onto a binary structured grid and porosity maps were generated for geometric comparison. The average binary accuracy score is 0.836 and the average error in porosity map is 6.3%. We then conduct patient-specific CFD simulations of the aneurysm hemodynamics using virtual coils geometries, micro-CT generated oil geometries, and using the porous medium method to represent the coil mass. Hemodynamic parameters of interest including were calculated for each of the CFD simulations. The average error across hemodynamic parameters of interest is ∼19%, a 58% reduction from the average error of the porous media simulations, demonstrating a marked improvement in the accuracy of CFD simulations using FEM generated coil geometries.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Improving Computational Fluid Dynamics Simulations of Coiled Aneurysms Using Finite Element Modeling

Fillingham

Bhathal

Marsh

et al. 2023

Preprint

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“…Our group has extensive experience simulating blood flow through cerebral aneurysms 3,6,12,24 and has previously developed a thorough methodology for conducting CFD simulations of both treated and untreated aneurysms. 6,[24][25][26][27][28] Briefly, a commercial finite volume solver (Ansys Fluent) was used to solve the transient 3-D incompressible Navier-Stokes equations.…”

Section: Computational Methodologymentioning

confidence: 99%

Standardized viscosity as a source of error in computational fluid dynamic simulations of cerebral aneurysms

Fillingham,

Belur,

Sweem

et al. 2023

Medical Physics

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BackgroundComputational fluid dynamics (CFD) simulations are a powerful tool for studying cerebral aneurysms, capable of evaluating hemodynamics in a way that is infeasible with imaging alone. However, the difficulty of incorporating patient‐specific information and inherent obstacles of in vivo validation have limited the clinical usefulness of CFD of cerebral aneurysms. In this work we investigate the effect of using standardized blood viscosity values in CFD simulations of cerebral aneurysms when compared to simulations of the same aneurysms using patient‐specific viscosity values derived from hematocrit measurements.PurposeThe objective of this work is to determine the level of error, on average, that is, caused by using standardized values of viscosity in CFD simulations of cerebral aneurysms. By quantifying this error, we demonstrate the need for incorporating patient‐specific viscosity in future CFD investigations of cerebral aneurysms.MethodsCFD simulations of forty‐one cerebral aneurysms were conducted using patient‐specific boundary conditions. For each aneurysm two simulations were conducted, one utilizing patient‐specific blood viscosity derived from hematocrit measurements and another using a standardized value for blood viscosity. Hemodynamic parameters such as wall shear stress (WSS), wall shear stress gradient (WSSG), and the oscillatory shear index (OSI) were calculated for each of the simulations for each aneurysm. Paired t‐tests for differences in the time‐averaged maps of these hemodynamic parameters between standardized and patient‐specific viscosity simulations were conducted for each aneurysm. Bland–Altman analysis was used to examine the cohort‐wide changes in the hemodynamic parameters. Subjects were broken into two groups, those with higher than standard viscosity and those with lower than standard viscosity. An unpaired t‐test was used to compare the percent change in WSS, WSSG, and OSI between patient‐specific and standardized viscosity simulations for the two cohorts. The percent changes in hemodynamic parameters were correlated against the direction and magnitude of percent change in viscosity, aneurysm size, and aneurysm location. For all t‐tests, a Bonferroni‐corrected significance level of 0.0167 was used.Results63.2%, 41.5%, and 48.7% of aneurysms showed statistically significant differences between patient‐specific and standardized viscosity simulations for WSS, WSSG, and OSI respectively. No statistically significant difference was found in the percent changes in WSS, WSSG, and OSI between the group with higher than standard viscosity and those with lower than standard viscosity, indicating an increase in viscosity can cause either an increase or decrease in each of the hemodynamic parameters. On a study‐wide level no significant bias was found in either direction for WSS, WSSG, or OSI between the simulation groups due to the bidirectional effect of changing viscosity. No correlation was found between percent change of viscosity and percent change of WSS, WSSG, or OSI, meaning an after‐the‐fact correction for patient‐specific viscosity is not feasible.ConclusionStandardizing viscosity values in CFD of cerebral aneurysms has a large and unpredictable impact on the calculated WSS, WSSG, and OSI when compared to CFD simulations of the same aneurysms using a patient‐specific viscosity. We recommend implementing hematocrit‐based patient‐specific blood viscosity values for all CFD simulations of cerebral aneurysms.

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Towards Prediction of Blood Flow in Coiled Aneurysms Before Treatment: A Porous Media Approach

Romero Bhathal,

Marsh,

Levitt

et al. 2023

Ann Biomed Eng

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Modeling Flow in Cerebral Aneurysm After Coils Embolization Treatment: A Realistic Patient-Specific Porous Model Approach

Cited by 3 publications

References 25 publications

Improving Computational Fluid Dynamics Simulations of Coiled Aneurysms Using Finite Element Modeling

Improving Computational Fluid Dynamics Simulations of Coiled Aneurysms Using Finite Element Modeling

Standardized viscosity as a source of error in computational fluid dynamic simulations of cerebral aneurysms

Towards Prediction of Blood Flow in Coiled Aneurysms Before Treatment: A Porous Media Approach

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