Key result
A new methodology combining a zero-pressure geometry algorithm and finite-element analysis demonstrated moderate accuracy in predicting AAA wall stress, with a 1.14% relative difference.
A new experimental methodology using AAA phantoms and μCT scanning provides a moderately accurate way to verify numerical wall stress predictions, highlighting the importance of wall thickness and mean curvature.
Hypothesis-generating for AAA wall stress modeling; human validation required before any clinical consideration.
An abdominal aortic aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from the numerical studies against the experimental testing. To this end, four AAA phantoms were manufactured using vacuum casting. The geometry of each phantom was subject to microcomputed tomography (μCT) scanning at zero and three other intraluminal pressures: 80, 100, and 120 mm Hg. A zero-pressure geometry algorithm was used to calculate the wall stress in the phantom, while the numerical wall stress was calculated with a finite-element analysis (FEA) solver based on the actual zero-pressure geometry subjected to 80, 100, and 120 mm Hg intraluminal pressure loading. Results demonstrate the moderate accuracy of this methodology with small relative differences in the average wall stress (1.14%). Additionally, the contribution of geometric factors to the wall stress distribution was statistically analyzed for the four phantoms. The results showed a significant correlation between wall thickness and mean curvature (MC) with wall stress.
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Galarreta et al. (2016) studied Abdominal aortic aneurysm (n=4). Zero-pressure geometry algorithm and finite-element analysis vs. Experimental testing was evaluated on Average wall stress relative difference. A new methodology combining a zero-pressure geometry algorithm and finite-element analysis demonstrated moderate accuracy in predicting AAA wall stress, with a 1.14% relative difference.
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