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Estimating patient specific wall shear stress in the human aorta: geometrical and post-processing considerations
Linköping University, Department of Mechanical Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, The Institute of Technology.
2006 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes a workflow to perform in-vivo wall shear stress (WSS) estimations in the human aorta using computational fluid dynamics (CFD) methods. An abnormal WSS distribution is believed to influence the development of many cardiovascular diseases, e.g. atherosclerosis. The focus in this thesis is on geometrical influence on the WSS results and interpretation methods tor non-stationary results. The work shows that results are sensitive to the choice of segmentation method (the process from medical images to a geometrical model) and a correct geometrical description of the artery is crucial in making WSS estimations. A new parameter for non-stationary WSS results has been proposed; Wall Shear Stress Angular Amplitude (WSSAA), making the analysis of non-stationary results more straight-forward. It has been shown that the workfiow can be used with confidence and that WSS can be estimated in-vivo. using the combination of MRI-based geometry definition and CFD.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2006. , 29 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1275
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-36904Local ID: 32991ISBN: 91-85643-75-0 (print)OAI: oai:DiVA.org:liu-36904DiVA: diva2:257753
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-12-19
List of papers
1. Geometrical Considerations in Patient Specific Models of a Human Aorta with Stenosis and Aneurysm
Open this publication in new window or tab >>Geometrical Considerations in Patient Specific Models of a Human Aorta with Stenosis and Aneurysm
2004 (English)In: Computational Fluid Dynamics 2004: Proceedings of the Third International Conference on Computational Fluid Dynamics, ICCFD3, Toronto, 12–16 July 2004, 2004, 335-340 p.Conference paper, Published paper (Refereed)
Abstract [en]

The most important artery in the human body is the aorta that supplies the rest of the body with blood. Lesions in the aorta can cause serious complications, which can even lead to death. How the flow is behaving in lesions, what causes the problems and which lesions are dangerous are highly interesting to determine. Laminar, stationary CFD calculations are performed on two geometrically different models of the human aorta created from the same set of patient MRI (Magnetic Resonance Imaging) data. Differences in the CFD results due to different geometries are evaluated. Overview results e.g. pressure variations throughout the artery are not dependent on an exact description of the geometry. If absolute and local values e.g. wall shear stress are sought more robust geometry creation procedure is needed in order to get more reliable results.

Keyword
Geometrical considertions, Human Aorta
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-23244 (URN)10.1007/3-540-31801-1_46 (DOI)2661 (Local ID)978-3-540-31800-2 (ISBN)2661 (Archive number)2661 (OAI)
Conference
Third International Conference on Computational Fluid Dynamics, ICCFD3, Toronto, 12–16 July 2004
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2016-03-14
2. Assessment of Geometrical Influence on WSS Estimation in the Human Aorta
Open this publication in new window or tab >>Assessment of Geometrical Influence on WSS Estimation in the Human Aorta
2006 (English)In: WSEAS Transactions on Fluid Mechanics, ISSN 1790-5087, Vol. 4, no 1, 318-326 p.Article in journal (Refereed) Published
Abstract [en]

Computational fluid dynamics simulations were performed on a stenosed human aorta with poststenotic dilatation, in order to estimate wall shear stress (WSS). WSS is important due to its correlation with atherosclerosis. Both steady-state and non-stationary simulations were conducted. Three different models were created from a set of MRI images. Comparison of geometrically different models was accomplished by using geometrical landmarks and a comparison parameter. Geometrical differences had larger influence on WSS magnitude than inflow rotation in steady-state results for the models used. In non-stationary flow the largest differences in WSS are found when the flow velocity near the wall is low e.g. when the inflow is low or in recirculation regions.

Keyword
wall shear stress, human aorta, geometry influence, cfd, result, comparison
National Category
Engineering and Technology Radiology, Nuclear Medicine and Medical Imaging Medical Image Processing Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:liu:diva-37433 (URN)35727 (Local ID)35727 (Archive number)35727 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2016-03-14
3. Post-Processing Dynamic Behavior of WSS in Aortic Blood Flow
Open this publication in new window or tab >>Post-Processing Dynamic Behavior of WSS in Aortic Blood Flow
2006 (English)Report (Other academic)
Abstract [en]

Pulsating flow simulations with CFD is performed on a stenosed human aorta with post-stenotic dilatation, for development of wall shear stress (WSS) dynamic parameters. WSS is of interest due to its correlation with atherosclerosis. The dynamic behavior and dynamic capturing parameters of WSS are usable in analyzing non-stationary results from blood flow simulations. The amount of wall back-flow is shown to be an very easy parameter to interpret and it showed an "washout" effect in the post-stenotic dilatation. A new dynamic capturing parameter describing the WSS angular amplitude (WSSAA) is presented. It has both differences and similarities with the widely used oscillating shear index (OSI) parameter. WSSA have a more direct physical interpretation then OSI.

Place, publisher, year, edition, pages
Linköping: Linköpings Universitetet, 2006
Series
LITH-IKP-R, ISSN 0281-5001 ; 6
Keyword
WallShear Stress, Human Aorta, CFD, WSS angular amplitude, Wall back-flow
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-36744 (URN)LITH-IKP-R--06/1417--SE (ISRN)32311 (Local ID)32311 (Archive number)32311 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2016-03-14
4. Feasibility of Patient Specific Aortic Blood Flow CFD Simulation
Open this publication in new window or tab >>Feasibility of Patient Specific Aortic Blood Flow CFD Simulation
Show others...
2006 (English)In: Medical Image Computing and Computer-Assisted Intervention – MICCAI 2006: 9th International Conference, Copenhagen, Denmark, October 1-6, 2006. Proceedings, Part I / [ed] Rasmus Larsen, Mads Nielsen and Jon Sporring, Springer Berlin/Heidelberg, 2006, 1, Vol. 4190, 257-263 p.Conference paper, Published paper (Refereed)
Abstract [en]

Patient specific modelling of the blood flow through the human aorta is performed using computational fluid dynamics (CFD) and magnetic resonance imaging (MRI). Velocity patterns are compared between computer simulations and measurements. The workflow includes several steps: MRI measurement to obtain both geometry and velocity, an automatic levelset segmentation followed by meshing of the geometrical model and CFD setup to perform the simulations follwed by the actual simulations. The computational results agree well with the measured data.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2006 Edition: 1
Series
Lecture Notes in Computer Science, ISSN 0302-9743 (print), 1611-3349 (online) ; 4190
National Category
Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-36902 (URN)10.1007/11866565_32 (DOI)000241556300032 ()32988 (Local ID)3-5404-4707-5 (ISBN)978-3-540-44727-6 (ISBN)978-3-540-44707-8 (ISBN)32988 (Archive number)32988 (OAI)
Conference
The 9th MICCAI Conference, Copenhagen, Denmark, 1-6 October 2006
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-03-27Bibliographically approved

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Renner, Johan

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