• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.224-227
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• 2010

In the present study, the characteristics of blood flow inside a carotid artery numerically investigated with shear rate specific blood viscosity. To simulate the blood flow with a patient-specific arterial geometry, the geometry of a carotid artery was constructed from 2D rain MRA data. The measured data of blood flow velocity at the common carotid artery were used as boundary conditions of the simulation. For the blood rheology data to be used in the simulation, the patient specific blood viscosity over the whole ranges of shear rate was obtained using $BioVisco^{TM}$. From the numerical results of the blood flow in the carotid artery, the increase of blood viscosity and the decrease of wall shear stress could be found in the carotid bifurcated region, more specifically at the post-plaque dilated region. These characteristics of blood viscosity and wall shear stress can be used more precisely and efficiently to predict the region vulnerable to plaque growht or thrombosis on top of the plaque.

• Investigative Magnetic Resonance Imaging
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• v.14 no.1
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• pp.47-55
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• 2010

Purpose : To evaluate the geometry of carotid artery by assessing the images of contrast-enhanced MR angiography (CE-MRA) and interrelationships between the geometry of carotid artery and clinical factors. Materials and Methods : 216 consecutive patients who performed supraaortic CE-MRA with fast spoiled gradient-echo imaging were included. Their medical records were reviewed for variable information including risk factors predictive of generalized atherosclerotic disease (age, hypertension (HTN), diabetes mellitus, hyperlipidema, and smoking), sex, body weight, height, and body mass index (BMI). We reviewed the CE-MRA with carotid origin (3 types), carotid artery tortuosity, angle of internal carotid artery bifurcation, the type of aortic arch branching, and the presence of the coiling of carotid artery. Results : Multinomial logistic regression analysis showed that significantly contributed clinical backgrounds for carotid origin were the age and the BMI. With an increase of age at 1, the probability that the type of carotid origin become from type 1 to type 2 was 0.9 times (p=0.004) in right carotid artery (RCA), 0.9 times (p = 0.031) in left carotid artery (LCA), 0.9 times that are likely to be type3 from type 2 (p<0.001) in RCA and 0.9 times in LCA (p=0.009). Increase in BMI at 1 increased odds of becoming type 2 as 1.1 times (p = 0.067) in RCA, 1.1 times (p=0.009) in LCA and increased chance of becoming type 3 as 1.2 times (p = 0.001) in RCA, 1.2 times (p=0.003) in LCA. Mean value of right and left carotid tortuosity were $240.9{\pm}69.0^{\circ}$and $154.4{\pm}55.0^{\circ}$, respectively. Conclusion : The BMI, age, sex and presence of HTN affects the geometry of carotid arteries, the site of origin and tortuosity of carotid artery specifically.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.181-185
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• 2008

In this study, we attempted to quantify the relative importance of assumptions regarding blood rheology. Three patient-specific carotid bifurcation geometries and time-varying flow rates were obtained using magnetic resonance imaging. For each subject, CFD simulations were carried out assuming two different non-Newtonian rheology models Carreau and Ballyk models) and rescaled Newtonian viscosities based on characteristic shear rates to account for the shear-thinning property of blood. The sensitivity of WSS and oscillatory shear index (OSI) were contextualized with respect to the reproducibility of the reconstructed geometry and to assumptions regarding the inlet boundary conditions. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the distribution of WSS-based extrema in an image-based CFD model of carotid bifurcation.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.181-185
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• 2008

In this study, we attempted to quantify the relative importance of assumptions regarding blood rheology. Three patient-specific carotid bifurcation geometries and time-varying flow rates were obtained using magnetic resonance imaging. For each subject, CFD simulations were carried out assuming two different non-Newtonian rheology models (Carreau and Ballyk models) and rescaled Newtonian viscosities based on characteristic shear rates to account for the shear-thinning property of blood. The sensitivity of WSS and oscillatory shear index (OSI) were contextualized with respect to the reproducibility of the reconstructed geometry and to assumptions regarding the inlet boundary conditions. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the distribution of WSS-based extrema in an image-based CFD model of carotid bifurcation.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.479-486
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• 2011

In image-based CFD modeling of carotid bifurcation hemodynamics, it is often not possible (or at least not convenient) to impose measured velocity profiles at the common carotid artery inlet. Instead, fully-developed velocity profiles are usually imposed based on measured flow rates. However, some studies reported a pronounced influence of inflow boundary conditions that were based on actual velocity profiles measured by magnetic resonance imaging which showing the unusual presence of a high velocity band in the middle of the vessel during early diastole inconsistent with a Dean-type velocity profile. We demonstrated that those velocity profiles were induced by the presence of modest secondary curvature of the inlet and set about to test whether such more "realistic" velocity profiles might indeed have a more pronounced influence on the carotid bifurcation hemodynamics. We found that inlet boundary condition with axisymmetric fully-developed velocity profile(Womersley flow) is reasonable as long as sufficient CCA inlet length of realistic geometry is applied.