scholarly journals A Workflow for Patient-Individualized Virtual Angiogram Generation Based on CFD Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Jürgen Endres ◽  
Markus Kowarschik ◽  
Thomas Redel ◽  
Puneet Sharma ◽  
Viorel Mihalef ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Cfd Simulation ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Risk Of Rupture ◽  
Computational Fluid Dynamics Cfd ◽  
Subsequent Comparison

Increasing interest is drawn on hemodynamic parameters for classifying the risk of rupture as well as treatment planning of cerebral aneurysms. A proposed method to obtain quantities such as wall shear stress, pressure, and blood flow velocity is to numerically simulate the blood flow using computational fluid dynamics (CFD) methods. For the validation of those calculated quantities, virtually generated angiograms, based on the CFD results, are increasingly used for a subsequent comparison with real, acquired angiograms. For the generation of virtual angiograms, several patient-specific parameters have to be incorporated to obtain virtual angiograms which match the acquired angiograms as best as possible. For this purpose, a workflow is presented and demonstrated involving multiple phantom and patient cases.

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

CFD Study on Effect of Branch Sizes in Human Coronary Arteries

2011 ◽  
Author(s):  
Liza Shrestha ◽  
Justin Garvin ◽  
Richard W. Downe ◽  
Milan Sonka ◽  
Andreas Wahle ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Coronary Artery Disease ◽  
Blood Flow ◽  
Shear Stress ◽  
Causes Of Death ◽  
Developed Countries ◽  
Unidirectional Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Artery Disease ◽  
Blood Flow Patterns

Coronary Artery Disease (CAD) is one of the leading causes of death in developed countries. The link between Wall Shear Stress (WSS) and CAD development is well established, with studies indicating the accumulation of lesions in regions of low WSS, flow separation, and in the regions where there is departure from axially aligned unidirectional flow [5]. It has been well established that blood flow patterns are highly affected by branch flows, as bifurcations are one of the leading locations of plaque accumulation [5]. Computational fluid dynamics (CFD) is an important tool for quantifying hemodynamics.

scholarly journals Numerical Analysis of Blood Flow Through Discrete Stenosis: Role of Eccentricity and Spacing Ratio

2017 ◽  
Author(s):  
Siyeong Ju ◽  
Linxia Gu
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Recirculation Zone ◽  
Cfd Simulation ◽  
Flow Region ◽  
Flow Recirculation ◽  
Spacing Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Interference

Stenosis or narrowing of arteries induces a turbulent flow region downstream. Multiple stenosis may lead to flow interference and further disturb the blood flow. This has important clinical implications [1], such as disturbed blood flow and flow recirculation which were correlated with the development of atherosclerosis by upregulating the endothelial cells genes and proteins that cause atherogenesis [2]. Numerical simulation of concentric stenoses by Lee et al [3] have shown that the recirculation zone following the first concentric stenosis affected the flow field at the downstream of the second one, which was dependent on the spacing ratio and degree of stenosis. However, the majority of stenosis is eccentric [2] and the detailed fluid dynamics of multiple stenoses with eccentric constrictions is lacking. The aim of this study is to investigate the interactions between double stenoses with eccentricity using computational fluid dynamics (CFD) simulation. The role of spacing ratio on the recirculation zone and turbulence intensity (TI) were characterized and also compared to concentric cases.

Investigation of two-way fluid-structure interaction of blood flow in a patient-specific left coronary artery

2021 ◽  
pp. 1-18
Author(s):  
Abdulgaphur Athani ◽  
N.N.N. Ghazali ◽  
Irfan Anjum Badruddin ◽  
Sarfaraz Kamangar ◽  
Ali E. Anqi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Left Coronary Artery ◽  
Fluid Structure Interaction ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Fluid Structure ◽  
Structure Interaction

BACKGROUND: The blood flow in the human artery has been a subject of sincere interest due to its prime importance linked with human health. The hemodynamic study has revealed an essential aspect of blood flow that eventually proved to be paramount to make a correct decision to treat patients suffering from cardiac disease. OBJECTIVE: The current study aims to elucidate the two-way fluid-structure interaction (FSI) analysis of the blood flow and the effect of stenosis on hemodynamic parameters. METHODS: A patient-specific 3D model of the left coronary artery was constructed based on computed tomography (CT) images. The blood is assumed to be incompressible, homogenous, and behaves as Non-Newtonian, while the artery is considered as a nonlinear elastic, anisotropic, and incompressible material. Pulsatile flow conditions were applied at the boundary. Two-way coupled FSI modeling approach was used between fluid and solid domain. The hemodynamic parameters such as the pressure, velocity streamline, and wall shear stress were analyzed in the fluid domain and the solid domain deformation. RESULTS: The simulated results reveal that pressure drop exists in the vicinity of stenosis and a recirculation region after the stenosis. It was noted that stenosis leads to high wall stress. The results also demonstrate an overestimation of wall shear stress and velocity in the rigid wall CFD model compared to the FSI model.

WHICH MORPHOLOGIC AND HEMODYNAMIC CHARACTERISTICS PREDICT INTRACRANIAL FUSIFORM ANEURYSMS RUPTURE? A PATIENT-SPECIFIC COMPUTATIONAL FLUID DYNAMICS STUDY

2017 ◽  
Vol 17 (03) ◽  
pp. 1750070
Author(s):  
YAN CHEN ◽  
YI-BIN FANG ◽  
PENG-FEI YANG ◽  
QING-HAI HUANG ◽  
JIAN-MIN LIU
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Patient Specific ◽  
Parent Artery ◽  
Cross Sectional ◽  
3D Angiography ◽  
Cross Section Area ◽  
Increased Risk ◽  
Risk Of Rupture

To identify hemodynamic and morphological parameters leading to increased risk of intracranial fusiform aneurysms (IFA) rupture using computational fluid dynamics (CFDs). A total of 24 patient-specific fusiform aneurysms models on vertebral artery were reconstructed from 3D angiography images. 11 ruptured cases and 13 unruptured cases were included. Morphologic parameters were measured and CFD parameters were calculated using CFD simulation. The length of the aneurysm is significantly shorter in ruptured group than in unruptured group. The ratio of the width to the length of an aneurysm (WLR) and the ratio of the cross-section area to the length of an aneurysm (ALR) to the averaged cross sectional areas of the inlet and outlet of the parent artery (ALaR) were significantly higher in ruptured group compared with unruptured group. Wall shear stress (WSS) of the aneurysm was normalized to the WSS of the parent artery. Hemodynamically, only low WSS was associated with higher risk of rupture. Ruptured IFAs are shorter, have bigger WLR, ALaR, and lower WSS, compared with unruptured IFAs.

Numerical Simulations of the Non-Newtonian Blood Blow in Human Abdominal Artery Based on Reverse Engineering

2011 ◽  
Vol 140 ◽  
pp. 195-199 ◽  
Author(s):  
Jin You YANG ◽  
Yang Hong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Fluid Flow ◽  
Reverse Engineering ◽  
Power Law ◽  
Cardiac Cycle ◽  
Hemodynamic Parameters ◽  
Human Artery ◽  
Computational Fluid Dynamics Cfd

The method that combined the reverse engineering based on CT medical images and computational fluid dynamics (CFD) was used to perform simulation the Non-Newtonian blood fluid flow in human abdominal artery, then analyzed the hemodynamic condition about the bifurcation of human abdominal artery. A Non-Newtonian blood model (the Generalised Power Law) was used to study the hemodynamic parameters during entire cardiac cycle. Calculated results for the Non-Newtonian blood flow show us the methods performed in this study is suitable for numerical simulating the blood flow in human artery and investigating the relation between hemodynamic factors and vascular disease.

Computational Fluid Dynamics of a Vascular Access Case for Hemodialysis

2000 ◽  
Vol 123 (3) ◽  
pp. 284-292 ◽  
Author(s):  
Bogdan Ene-Iordache ◽  
Lidia Mosconi ◽  
Giuseppe Remuzzi ◽  
Andrea Remuzzi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Radial Artery ◽  
Stress Gradient ◽  
Vascular Lesions ◽  
Patient Specific ◽  
Wall Shear

Vascular accesses (VA) for hemodialysis are usually created by native arteriovenous fistulas (AVF) or synthetic grafts. Maintaining patency of VA continues to be a major problem for patients with end-stage renal disease, since in these vessels thrombosis and intimal hyperplasia often occur. These lesions are frequently associated with disturbed flow that develops near bifurcations or sharp curvatures. We explored the possibility of investigating blood flow dynamics in a patient-specific model of end-to-end native AVF using computational fluid dynamics (CFD). Using digital subtraction angiographies of an AVF, we generated a three-dimensional meshwork for numerical analysis of blood flow. As input condition, a time-dependent blood waveform in the radial artery was derived from centerline velocity obtained during echo-color-Doppler ultrasound examination. The finite element solution was calculated using a fluid-dynamic software package. In the straight, afferent side of the radial artery wall shear stress ranged between 20 and 36 dynes/cm2, while on the inner surface of the bending zone it increased up to 350 dynes/cm2. On the venous side, proximal to the anastomosis, wall shear stress was oscillating between negative and positive values (from −12 dynes/cm2 to 112 dynes/cm2), while distal from the anastomosis, the wall shear stress returned within the physiologic range, ranging from 8 to 22 dynes/cm2. Areas of the vessel wall with very high shear stress gradient were identified on the bending zone of the radial artery and on the venous side, after the arteriovenous shunt. Secondary blood flows were also observed in these regions. CFD gave a detailed description of blood flow field and showed that this approach can be used for patient-specific analysis of blood vessels, to understand better the role of local hemodynamic conditions in the development of vascular lesions.

scholarly journals Blood flow and coherent vortices in the normal and aneurysmatic aortas: a fluid dynamical approach to intra-luminal thrombus formation

2011 ◽  
Vol 8 (63) ◽  
pp. 1449-1461 ◽  
Author(s):  
Jacopo Biasetti ◽  
Fazle Hussain ◽  
T. Christian Gasser
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Cardiac Cycle ◽  
Thrombus Formation ◽  
Aortic Aneurysms ◽  
Patient Specific ◽  
Clear Correlation ◽  
Complex Flow ◽  
Dynamics Simulations

Abdominal aortic aneurysms (AAAs) are frequently characterized by the development of an intra-luminal thrombus (ILT), which is known to have multiple biochemical and biomechanical implications. Development of the ILT is not well understood, and shear–stress-triggered activation of platelets could be the first step in its evolution. Vortical structures (VSs) in the flow affect platelet dynamics, which motivated the present study of a possible correlation between VS and ILT formation in AAAs. VSs educed by the λ 2 -method using computational fluid dynamics simulations of the backward-facing step problem, normal aorta, fusiform AAA and saccular AAA were investigated. Patient-specific luminal geometries were reconstructed from computed tomography scans, and Newtonian and Carreau–Yasuda models were used to capture salient rheological features of blood flow. Particularly in complex flow domains, results depended on the constitutive model. VSs developed all along the normal aorta, showing that a clear correlation between VSs and high wall shear stress (WSS) existed, and that VSs started to break up during late systole. In contrast, in the fusiform AAA, large VSs developed at sites of tortuous geometry and high WSS, occupying the entire lumen, and lasting over the entire cardiac cycle. Downward motion of VSs in the AAA was in the range of a few centimetres per cardiac cycle, and with a VS burst at that location, the release (from VSs) of shear-stress-activated platelets and their deposition to the wall was within the lower part of the diseased artery, i.e. where the thickest ILT layer is typically observed. In the saccular AAA, only one VS was found near the healthy portion of the aorta, while in the aneurysmatic bulge, no VSs occurred. We present a fluid-dynamics-motivated mechanism for platelet activation, convection and deposition in AAAs that has the potential of improving our current understanding of the pathophysiology of fluid-driven ILT growth.

scholarly journals Propose a Wall Shear Stress Divergence to Estimate the Risks of Intracranial Aneurysm Rupture

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Y. Zhang ◽  
H. Takao ◽  
Y. Murayama ◽  
Y. Qian
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Intracranial Aneurysm ◽  
Risk Estimation ◽  
Aneurysm Rupture ◽  
Patient Specific ◽  
Luminal Surface ◽  
Risk Of Rupture ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Shear

Although wall shear stress (WSS) has long been considered a critical indicator of intracranial aneurysm rupture, there is still no definite conclusion as to whether a high or a low WSS results in aneurysm rupture. The reason may be that the effect of WSS direction has not been fully considered. The objectives of this study are to investigate the magnitude of WSS (WSS) and its divergence on the aneurysm surface and to test the significance of both in relation to the aneurysm rupture. Patient-specific computational fluid dynamics (CFD) was used to compute WSS and wall shear stress divergence (WSSD) on the aneurysm surface for nineteen patients. Our results revealed that if highWSSis stretching aneurysm luminal surface, and the stretching region is concentrated, the aneurysm is under a high risk of rupture. It seems that, by considering both direction and magnitude of WSS, WSSD may be a better indicator for the risk estimation of aneurysm rupture (154).

Sign in / Sign up

Export Citation Format

Share Document