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Modeling of flow in a straight stented and nonstented side wall aneurysm model."
- J Biomech Eng,
, 1997
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Numerical investigation for the effect of blood flow rate and asymmetric bifurcation angle on the anterior circulation aneurysm formation. ASME-JSME-KSME Joint Fluids Engineering Conference
, 2011
"... ABSTRACT Most of aneurysms in the cranial cavity occur at the bifurcation of anterior circulation system. A cerebral aneurysm is easily ruptured, and it is fatal for most patients. Generally it is known that aneurysm occurs when arterial wall is deformed by high pressure or high wall shear stress(W ..."
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ABSTRACT Most of aneurysms in the cranial cavity occur at the bifurcation of anterior circulation system. A cerebral aneurysm is easily ruptured, and it is fatal for most patients. Generally it is known that aneurysm occurs when arterial wall is deformed by high pressure or high wall shear stress(WSS). A blood flow pattern and the geometry and the blood vessel are important factors for aneurysm formation and the location. The transient interaction between blood flow and the arterial wall affects for simulating deformation of the blood vessel. Thus, numerical analysis is performed for various bifurcation angles and flow rate ratio in bifurcation artery with different diameters to predict the location of aneurysm by hemodynamic characteristics of blood flow. A bifurcation angle between the internal carotid artery and the anterior cerebral artery(ACA) increased, a region of high pressure moved to the bifurcated artery with larger bifurcation angle when ratio of blood flow rate is constant case. When the ratio of blood flow increased, the region of high wall shear stress moved to the side of large flow rate ratio. Our results showed that the high WSS or high pressure region occur at the location of aneurysm as mentioned in the clinical research. Thus, this indicates that the geometry of blood vessel and blood flow rate affect the location of the anterior circulation aneurysm.
Modeling, Simulation and VR Visualization of Brain Aneurysm Blood Flow
, 1996
"... representation of graphic object in some abstract field. class VirtualObject -- private: DynVar!bool? Active; DynVar!bool? Focus; DynVar!Position? Pos; DynVar!Quaternion? Ori; DynVar!Position? PosRef; DynVar!Quaternion? OriRef; DynVar!Position? PosRel; DynVar!Quaternion? OriRel; bool AbsRefFrame; Fl ..."
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representation of graphic object in some abstract field. class VirtualObject -- private: DynVar!bool? Active; DynVar!bool? Focus; DynVar!Position? Pos; DynVar!Quaternion? Ori; DynVar!Position? PosRef; DynVar!Quaternion? OriRef; DynVar!Position? PosRel; DynVar!Quaternion? OriRel; bool AbsRefFrame; Flowfield* Ff; public: VirtualObject(); VirtualObject(Flowfield& ff); 171 VirtualObject& operator=(const VirtualObject& v); VirtualObject(const VirtualObject& v); virtual ~VirtualObject(); /// Is the object on? virtual bool active(); /// The update function should be called on every simulation loop. virtual void update(int framecount) = 0; /// Turn on object. virtual void activate(void); /// Turn off object. virtual void deactivate(void); /// Turn on object focus. virtual void focus(void); /// Turn off object focus. virtual void defocus(void); /// Returns the position of the tool. virtual Position position(void); /// Returns the orientation of the tool. virtual Quaternion orientation(void); ...
DEVELOPMENT OF A MODEL FOR THE INVESTIGATION OF BLOOD CLOTTING IN CEREBRAL ANEURYSMS FOLLOWING COILING
"... Abstract One of the methods of treatment of intracranial aneurysms involves packing of the aneurysm with small Guglielmi Detachable Coils (GDC). The purpose of this treatment is to induce clotting within the aneurysm thus preventing rupture. It is suggested that changes in haemodynamic flow patterns ..."
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Abstract One of the methods of treatment of intracranial aneurysms involves packing of the aneurysm with small Guglielmi Detachable Coils (GDC). The purpose of this treatment is to induce clotting within the aneurysm thus preventing rupture. It is suggested that changes in haemodynamic flow patterns associated with the partial filling of the aneurysm with an inert material is responsible for initiating the clotting process and occlusion of the aneurysm. A residence time based clotting model, previously validated experimentally for a simple geometry, was applied to the CFD analysis of an idealized aneurysm geometry. Coil geometry was included in an idealized form to allow the interaction of the blood with the coil to be modeled. A novel approach was employed using a combination of fluid residence time and concentration of ‘clottable ’ fluid to model the change in viscosity of the fluid during the clotting process.
Qualitative Comparison of Intra-aneurysmal Flow Structures Determined from Conventional and Virtual Angiograms
"... In this study we qualitatively compare the flow structures observed in cerebral aneurysms using conventional angiography and virtual angiograms produced from patient-specific computational fluid dynamics (CFD) models. For this purpose, high frame rate biplane angiograms were obtained during a rapid ..."
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In this study we qualitatively compare the flow structures observed in cerebral aneurysms using conventional angiography and virtual angiograms produced from patient-specific computational fluid dynamics (CFD) models. For this purpose, high frame rate biplane angiograms were obtained during a rapid injection of contrast agent in three patients with intracranial aneurysms. Patient-specific CFD models were then constructed from 3D rotational angiography images of each aneurysm. Time dependent flow fields were obtained from the numerical solution of the incompressible Navier-Stokes equations under pulsatile flow conditions derived from phase-contrast magnetic resonance measurements performed on normal subjects. These flow fields were subsequently used to simulate the transport of a contrast agent by solving the advection-diffusion equation. Both the fluid and transport equations were solved with an implicit finite element formulation on unstructured grids. Virtual angiograms were then constructed by volume rendering of the simulated dye concentration field. The flow structures observed in the conventional and virtual angiograms were then qualitatively compared. It was found that the finite element models showed distinct flow types for each aneurysm, ranging from simple to complex. The virtual angiograms showed good agreement with the images from the conventional angiograms for all three aneurysms. Analogous size and orientation of the inflow jet, regions of flow impaction, major intraaneurysmal vortices and regions of outflow were observed in both the conventional and virtual angiograms. In conclusion, patient-specific image-based computational models of intracranial aneurysms can realistically reproduce the major intraaneurysmal flow structures observed with conventional angiography.
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"... Downloaded Fpacking agents such as balloon and/or platinum microcoils are likely to extent or migrate from the aneurysm into the parent vessel, an alternative approach is intravascular stenting ..."
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Downloaded Fpacking agents such as balloon and/or platinum microcoils are likely to extent or migrate from the aneurysm into the parent vessel, an alternative approach is intravascular stenting
