University of Twente Student Theses
Computational fluid dynamics in the stented arteria femoralis superficialis
Rutten, L. (2020) Computational fluid dynamics in the stented arteria femoralis superficialis.
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| Abstract: | Introduction: Visualizing the blood flow could provide a better understanding and improved prediction of the development of an in-stent restenosis in the arteria femoralis superficialis (AFS). Computational fluid dynamics (CFD) could be used to simulate the complex blood flow, but simplifications and assumptions are necessary to reduce the complexity of the computational model and compensate for the lack of (adequate) patient-specific data that could affect the CFD solution. In this thesis the effect of uncertainty in the patient-specific geometry and inlet velocity profile on the CFD solution in the stented AFS is investigated. Method: The uncertainty in lumen segmentation that is induced by blooming artifacts by radiopaque stent markers and stent-in-stent placement was quantified in-vitro. The visible lumen, strut thickness, contrast-to-noise ratio and signal-to-noise ratio were compared between conventional and spectral image reconstructions and analysis locations. Sensitivity of the CFD solution to uncertainty in the lumen diameter near radiopaque stent markers in the patient-specific geometry was analyzed. Furthermore, an analytical Womersley and measured echo particle image velocimetry (echo PIV) velocity profile were compared. Velocity streamlines and regions of low time-averaged wall shear stress (TAWSS) (<0.4 Pa) were visualized to analyze the effect of on the CFD solution. Results: The blooming artifact showed the largest reduction in the conventional iterative model reconstruction (IMR) and was most prominent near proximal/distal radiopaque stent markers causing an underestimation of the in-stent lumen of 33%. Uncertainty in the geometry near proximal/distal radiopaque stent markers caused local changes in the CFD solution. Overestimation of approximately 33% resulted in an increased region of low TAWSS of a factor ten in the proximal AFS. Over- and underestimation of approximately 16% caused an increased region of low TAWSS of a factor three and two, respectively, in the AFS, resulting in a global difference of approximately 10%. Uncertainty in inlet velocity profile induced local changes in the CFD solution of 30% in the AFC, resulting in a global difference of 14.6%. Differences in flow rate caused global differences in the CFD solution up to 250%. Conclusion: Blooming showed the largest reduction in the IMR image reconstruction and was most prominent near proximal/distal radiopaque stent markers. Uncertainty in the geometry near these stent markers caused local changes in the CFD solution. Uncertainty in the inlet velocity profile resulted in local changes in the CFD solution as well. The effect of uncertainty in the geometry and inlet velocity profile on the global CFD solution were significantly smaller than the effect of the flow rate on the global CFD solution. |
| Item Type: | Essay (Master) |
| Faculty: | TNW: Science and Technology |
| Subject: | 44 medicine, 52 mechanical engineering |
| Programme: | Technical Medicine MSc (60033) |
| Link to this item: | https://purl.utwente.nl/essays/81252 |
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