期刊
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
卷 129, 期 1, 页码 105-109出版社
ASME
DOI: 10.1115/1.2401189
关键词
abdominal aortic aneurysm; AAA; calcification; finite element analysis; wall stress
资金
- NHLBI NIH HHS [R01 HL079313, R01 HL060670] Funding Source: Medline
It is generally acknowledged that rupture of an abdominal aortic aneurysm (AAA) occurs when the stress acting on the wall over the cardiac cycle exceeds the strength of the wall. Peak wall stress computations appear to give a more accurate rupture risk assessment than AAA diameter which is currently used for a diagnose. Despite the numerous studies utilizing patient-specific wall stress modeling of AAAs, none investigated the effect of wall calcifications on wall stress. The objective of this study was to evaluate the influence of calcifications on patient-specific finite element stress computations. In addition, we assessed whether the effect of calcifications could be predicted directly from the CT-scans by relating the effect to the amount of calcification present in the AAA wall. For 6 AAAs, the location and extent of calcification was identified from CT-scans. A finite element model was created,for each AAA and the areas of calcification were defined node-wise in the mesh of the model. Comparisons are made between maximum principal stress distributions, computed without calcifications and with calcifications with varying material properties. Peak stresses are determined from the stress results and related to a calcification index(CI), a quantification of the amount of calcification in the AAA wall. At calcification sites, local stresses increased, leading to a peak stress increase of 22% in the most severe case. Our results displayed a weak correlation between the CI and the increase in peak stress. Additionally, the results showed a marked influence of the calcification elastic modulus oil computed stresses. Inclusion of calcifications ill finite element analysis of AAAs resulted in a marked alteration of the stress distributions and should there re be included ill rupture risk assessment. The results also suggest that the location and shape of the calcified regions-not only the relative amount-are considerations that influence the effect oil AAA wall stress. The dependency a the effect of the wall stress oil the calcification elastic modulus points out the importance of determination of the material properties of calcified AAA wall.
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