Size-Dependent Distribution of Patient-Specific Hemodynamic Factors in Unruptured Cerebral Aneurysms Using Computational Fluid Dynamics.

Ui Yun Lee,Jinmu Jung,Gyung Ho Chung,Hyo Sung Kwak

doi:10.3390/diagnostics10020064

Ui Yun Lee, Jinmu Jung + Show 2 more

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https://doi.org/10.3390/diagnostics10020064

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Abstract

Purpose: To analyze size-dependent hemodynamic factors [velocity, shear rate, blood viscosity, wall shear stress (WSS)] in unruptured cerebral aneurysms using computational fluid dynamics (CFD) based on the measured non-Newtonian model of viscosity. Methods: Twenty-one patients with unruptured aneurysms formed the study cohort. Patient-specific geometric models were reconstructed for CFD analyses. Aneurysms were divided into small and large groups based on a cutoff size of 5 mm. For comparison between small and large aneurysms, 5 morphologic variables were measured. Patient-specific non-Newtonian blood viscosity was applied for more detailed CFD simulation. Quantitative and qualitative analyses of velocity, shear rate, blood viscosity, and WSS were conducted to compare small and large aneurysms. Results: Complex flow patterns were found in large aneurysms. Large aneurysms had a significantly lower shear rate (235 ± 341 s−1) than small aneurysms (915 ± 432 s−1) at peak-systole. Two times higher blood viscosity was observed in large aneurysms compared with small aneurysms. Lower WSS was found in large aneurysms (1.38 ± 1.36 Pa) than in small aneurysms (3.53 ± 1.22 Pa). All the differences in hemodynamic factors between small and large aneurysms were statistically significant. Conclusions: Large aneurysms tended to have complex flow patterns, low shear rate, high blood viscosity, and low WSS. The hemodynamic factors that we analyzed might be useful for decision making before surgical treatment of aneurysms.

Highlights

Detection of asymptomatic unruptured aneurysms has become feasible with the improvements in neuroimaging methods [1]
In this study, measured non-Newtonian viscosity was used for a patient-specific computational fluid dynamics (CFD) study to analyze hemodynamic factors such as velocity, shear rate, blood viscosity, and wall shear stress (WSS) according to aneurysm size
Cebral et al [25] reported that complex flow patterns and concentrated inflow jets were associated significantly with aneurysm rupture, whereas simple flow patterns and diffused inflow jets were found commonly in unruptured aneurysms

Summary

Introduction

Detection of asymptomatic unruptured aneurysms has become feasible with the improvements in neuroimaging methods [1]. After detection of unruptured aneurysms, appropriate treatment for rupture prevention is needed because the discovered unruptured aneurysms are not free from rupture risk [2]. The most widely used significant risk factor for rupture is aneurysm size [3,4], as a large aneurysm is more likely to rupture [5,6]. The risk of aneurysm rupture can be predicted using hemodynamic factors [2]. Since aneurysm size alone might be inappropriate to determine rupture risk of unruptured aneurysm, hemodynamic factors have been assessed using computational fluid dynamics (CFD) [4,5,8].

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