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A comparison of modelling techniques for computing wall stress in abdominal aortic aneurysms.

Doyle BJ, Callanan A, McGloughlin TM - Biomed Eng Online (2007)

Bottom Line: It was also noted that wall stress was shown to reduce by 59% when modelled using the most accurate non-linear complex approach, compared to the same model without intraluminal thrombus.The results here show that using more realistic parameters affect resulting wall stress.Care should be taken when examining stress results found using simplified techniques, in particular, if the wall stress results are to have clinical importance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical and Aeronautical Engineering and Materials and Surface Science Institute, University of Limerick, Ireland. barry.doyle@ul.ie

ABSTRACT

Background: Aneurysms, in particular abdominal aortic aneurysms (AAA), form a significant portion of cardiovascular related deaths. There is much debate as to the most suitable tool for rupture prediction and interventional surgery of AAAs, and currently maximum diameter is used clinically as the determining factor for surgical intervention. Stress analysis techniques, such as finite element analysis (FEA) to compute the wall stress in patient-specific AAAs, have been regarded by some authors to be more clinically important than the use of a "one-size-fits-all" maximum diameter criterion, since some small AAAs have been shown to have higher wall stress than larger AAAs and have been known to rupture.

Methods: A patient-specific AAA was selected from our AAA database and 3D reconstruction was performed. The AAA was then modelled in this study using three different approaches, namely, AAA(SIMP), AAA(MOD) and AAA(COMP), with each model examined using linear and non-linear material properties. All models were analysed using the finite element method for wall stress distributions.

Results: Wall stress results show marked differences in peak wall stress results between the three methods. Peak wall stress was shown to reduce when more realistic parameters were utilised. It was also noted that wall stress was shown to reduce by 59% when modelled using the most accurate non-linear complex approach, compared to the same model without intraluminal thrombus.

Conclusion: The results here show that using more realistic parameters affect resulting wall stress. The use of simplified computational modelling methods can lead to inaccurate stress distributions. Care should be taken when examining stress results found using simplified techniques, in particular, if the wall stress results are to have clinical importance.

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Related in: MedlinePlus

Normalised wall stress results and locations of peak wall stress in all the linearly elastic models examined. Wall stress results are normalised to the peak stress found in AAA(MOD)L. The figure shows the effect of modelling parameters and inclusion of the ILT on peak wall stress. The black mark indicates the region of peak wall stress. Location of peak stress for the AAA(MOD)L and AAA(COMP)L models are on the inner surface of the AAA wall. All models are shown in the anterior view.
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Figure 8: Normalised wall stress results and locations of peak wall stress in all the linearly elastic models examined. Wall stress results are normalised to the peak stress found in AAA(MOD)L. The figure shows the effect of modelling parameters and inclusion of the ILT on peak wall stress. The black mark indicates the region of peak wall stress. Location of peak stress for the AAA(MOD)L and AAA(COMP)L models are on the inner surface of the AAA wall. All models are shown in the anterior view.

Mentions: The effect of geometrical modelling parameters can be seen in Figure 8 for the linearly elastic models, and in Figure 9 for the non-linearly elastic models. The location of peak stress is also indicated in these figures. The wall stresses were normalised using the peak wall stress experienced in the linear elastic study (Figure 8) and the peak stress obtained in the non-linear elastic study (Figure 9). By comparing the three models examined from a linearly elastic approach, the AAA(MOD)L returned the highest peak stress of 2.282 MPa. Both the AAA(SIMP)L and AAA(COMP)L returned similar peak stresses of 0.8833 MPa and 0.8036 MPa, respectively.


A comparison of modelling techniques for computing wall stress in abdominal aortic aneurysms.

Doyle BJ, Callanan A, McGloughlin TM - Biomed Eng Online (2007)

Normalised wall stress results and locations of peak wall stress in all the linearly elastic models examined. Wall stress results are normalised to the peak stress found in AAA(MOD)L. The figure shows the effect of modelling parameters and inclusion of the ILT on peak wall stress. The black mark indicates the region of peak wall stress. Location of peak stress for the AAA(MOD)L and AAA(COMP)L models are on the inner surface of the AAA wall. All models are shown in the anterior view.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169238&req=5

Figure 8: Normalised wall stress results and locations of peak wall stress in all the linearly elastic models examined. Wall stress results are normalised to the peak stress found in AAA(MOD)L. The figure shows the effect of modelling parameters and inclusion of the ILT on peak wall stress. The black mark indicates the region of peak wall stress. Location of peak stress for the AAA(MOD)L and AAA(COMP)L models are on the inner surface of the AAA wall. All models are shown in the anterior view.
Mentions: The effect of geometrical modelling parameters can be seen in Figure 8 for the linearly elastic models, and in Figure 9 for the non-linearly elastic models. The location of peak stress is also indicated in these figures. The wall stresses were normalised using the peak wall stress experienced in the linear elastic study (Figure 8) and the peak stress obtained in the non-linear elastic study (Figure 9). By comparing the three models examined from a linearly elastic approach, the AAA(MOD)L returned the highest peak stress of 2.282 MPa. Both the AAA(SIMP)L and AAA(COMP)L returned similar peak stresses of 0.8833 MPa and 0.8036 MPa, respectively.

Bottom Line: It was also noted that wall stress was shown to reduce by 59% when modelled using the most accurate non-linear complex approach, compared to the same model without intraluminal thrombus.The results here show that using more realistic parameters affect resulting wall stress.Care should be taken when examining stress results found using simplified techniques, in particular, if the wall stress results are to have clinical importance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical and Aeronautical Engineering and Materials and Surface Science Institute, University of Limerick, Ireland. barry.doyle@ul.ie

ABSTRACT

Background: Aneurysms, in particular abdominal aortic aneurysms (AAA), form a significant portion of cardiovascular related deaths. There is much debate as to the most suitable tool for rupture prediction and interventional surgery of AAAs, and currently maximum diameter is used clinically as the determining factor for surgical intervention. Stress analysis techniques, such as finite element analysis (FEA) to compute the wall stress in patient-specific AAAs, have been regarded by some authors to be more clinically important than the use of a "one-size-fits-all" maximum diameter criterion, since some small AAAs have been shown to have higher wall stress than larger AAAs and have been known to rupture.

Methods: A patient-specific AAA was selected from our AAA database and 3D reconstruction was performed. The AAA was then modelled in this study using three different approaches, namely, AAA(SIMP), AAA(MOD) and AAA(COMP), with each model examined using linear and non-linear material properties. All models were analysed using the finite element method for wall stress distributions.

Results: Wall stress results show marked differences in peak wall stress results between the three methods. Peak wall stress was shown to reduce when more realistic parameters were utilised. It was also noted that wall stress was shown to reduce by 59% when modelled using the most accurate non-linear complex approach, compared to the same model without intraluminal thrombus.

Conclusion: The results here show that using more realistic parameters affect resulting wall stress. The use of simplified computational modelling methods can lead to inaccurate stress distributions. Care should be taken when examining stress results found using simplified techniques, in particular, if the wall stress results are to have clinical importance.

Show MeSH
Related in: MedlinePlus